Python Masterclass From Complete Beginner To Absolute Master

1. Why You Should Watch This Masterclass: Hi, my name is Michael, founder of Two M Python Death. I specialize in helping students go from complete beginners to absolute a masters in Python program. I've developed a strategy that has helped hundreds of students achieve their goals of becoming Python developers. And I want to do the same for you. But before I tell you how, you need to know that 92% of those that start Python programming stop within just two weeks due to ineffective learning methods. Watching Youtube videos, reading books, and doing projects of your own are not sufficient resources to fully grasp the concepts of Python coding and programming philosophy in general. At two Python deaf, we provide a clear learning structure with a unique approach that focuses on application and practice, rather than just watching and theory. Once you finish the course, you'll become a master problem solver. You will understand fundamental coding concepts such as object oriented programming in Python. You'll also become highly skilled in data handling using lists, couples, dictionaries, and sets, and you'll excel at working with databases using SQL language. You will receive personalized one on one lessons with highly trained instructors that specialize in teaching students Python, even if they have zero prior coding experience. Hi, sorry for cutting into the video so ruthlessly. But I had a few notes that I would like to add. We don't need a private instructor in order to finish this master class. Everything was thoroughly explained, so you can do it on your own. But if you're looking to save hundreds of hours, learn from experienced Python developers and guarantee that you become a Python developer yourself. I highly recommend that you go to two m Python dev.com forward slash private tutoring Python. I will have the link posted in here somewhere and I will leave it in my profile. Hey, just wanted to give you a quick tour of the website so you know your way around. First of all, you're going to be greeted with the elite Python one on one private tutoring lessons, you'll know why it's elite in just a bit. Then you'll see that we guarantee that you mastered Python in as little as ten weeks. And you'll see this button right here. Look what happens when you have over it. You won't believe how long it took me to do this, even if I told you. But anyways, when you click this button, you book a free call. You need to add your name, your best e mail, and make sure to add your phone number as well, so that I can contact you over what's up. And finally, click on this button right here to book your free 100% free strategy session. Next, right here, you can see that we have the video. You can watch it again, but it's basically the same one. And then you have the e mail where you can contact us at two point on dev. Or you can contact me personally using this number right here. You can actually click on this button and it will take you to Whatsapp. And you can then contact me directly from the next. If you scroll down, you'll see that this bar at the top hops up. This also took me a long time. So you can use it to go through different sections of this website. Right here we have the beliefs and you should really believe in your future as a Python developer, even if you have zero coding experience. So don't worry about that. Next you're going to see the Y learn with us. I'm not going to read all of this, You can do it on your own, but I'm going to skim over the main ideas. First of all, we build a solid programming foundation. We don't want to rush things, we want to make sure that you understand everything. Next, we are very beginner friendly and very advanced friendly as well, so you are covered on all sides. Time, flexibility, you choose what times you want to learn during the week and how many hours you want to learn. Next, we have a huge amount of time saved from studies. We've found that to learn four loops on your own, you need at least ten days to learn it in a class of ten or five, You need five days, but with private tutoring, one on one, private tutoring, you can learn it in as much as one or 2 hours. So you're saving a huge amounts of time, hundreds and hundreds of hours. Next, everything that we do is going to be project based. Everything that we learn is going to be applied to real world scenarios and practice. Practice, practice, every lesson will have a challenge that you need to complete, because doing is superior to watching In section three, these are the possible careers. So you are investing in a future where you could be earning up to $71,000 and this is the lowest end. You can see that you can either become data analyst, BI analyst, AI engineer, and data scientist. These are just the basics. You can always go to this website to check the numbers for yourself. This is why Python is such a good language. A nice graphic that I created right here. Also in here, you can see that we have this button now, the two M Python master class curriculum. I recommend that you go through every single section in here to understand how it works. I'm going to cover this in upcoming videos, but not in this one, because the most important section is going to be the success story. So I want you to go through this if you're still unsure whether we are legit. I love transparency. So I want you to read every single review that we have in here from different platforms. And the most important part is I want you to get to this point right here. Because any of these screenshots could be faked. I'm not going to lie, these can be faked easily. But the interviews that I have with the students that learned at two Python dev cannot be faked. As again, I love transparency. I want to be as transparent as possible and I want you to know exactly what you are getting yourself into. This is not a small amount of money that you would pay to learn Python Again, this is an investment in your future, but I want you to know exactly what you will get with the amount that you invest. So please take the time. Watch the videos. Understand these people's story. These people, they started from complete beginners and became absolute masters in Python programming. So I highly recommend that you watch these videos. Thank you so much for watching. I have the link in my profile if you want to check out all of these things for yourself. So the way this works is first you'll have a strategy session with me where you will learn all about the core structure, understand the benefits you'll get out of every single section, and we'll have a lesson together where I will assess your Python level and then pair you with the perfect instructor that will fit your exact needs. And unlike boot camps with large class sizes and rigid schedules, forcing you to attend specific hours during the week and charging you huge fees. On top of that, we offer a tailored learning experience, allowing you the freedom to choose flexible hours and the number of hours you want per week, all at a fraction of the cost. So if you're interested, book a call with us by clicking the button below, and I hope to see you soon. 2. Section 1 - Introduction | 1. Python For Windows Mac: Welcome back my favorite Python programmers. In this video, we're going to be talking about Python, what it is, how it works, just surface level things. Then we are going to go and download Python to set up the environment on your PC. First of all, what is Python? Python is this logo right here. Well, it's not just this logo, it's a high level and general purpose programming language. First of all, let's talk about a high level. High level means that we are using regular English language to communicate with our processor. We start off with the usual high level language, which is Python, Which is just words like print and hello world and things like that. And string and integer. Then it's converted into a cold code called assembly. We are not going to be looking into assembly in discourse. It's a bit of an advanced subject, very complicated subject. But I do recommend that you go and see how assembly looks like. It's basically like sending information and guides to the processor and telling the processor how it should interpret this information in zeros and one. And finally, we have the lowest level, which is just ones and zeros being sent to the processor. The processor then sending you back information. It's also a general purpose programming language, and that's the most fun and exciting part about Python, is that you can use it for data visualization, for data analytics, for software development, for AI, for front for back. You can even create games and websites using Python. So it's a general purpose programming language. Python is designed to emphasize code readability. So if you're coming from another language, you know that you have to use a lot of squiggly brackets, a lot of minute details to make sure that everything works. Python doesn't do that. Python uses indentations instead of brackets, and we're going to see all of that in our upcoming examples. Let's go ahead and download Python to our PC in here. I've already prepared the web page. All you need to do is go to Python.org I will leave the link somewhere maybe, but let's say very easy link. You can even type in Python.org on Google and you should find this website right here. First of all, you need to go and download and you can see all the releases. But if you're on a Windows or MX, I suggest selecting one of these two. I'm going to select Windows. When you go to Windows, you should see the latest version of Python. Now maybe you're watching this in the future and there's an even newer version than this one, but everything that's 3.8 and upwards I think is going to work 100% with whatever version you get. Everything above 3.8 is going to work with the course 100% Just click on latest Python release. Once you do that, the installer should get going. So right here you can see some general information and rules about this Python, this new release of Python. You should come down to the files right here and you should find or wait in here, you can see that this is Python 3.11 0.4 these are all just small versions. The most important thing is that you download Python three point something, it's faster. You can see right here, you can read a little bit about the general changes that were made. Sometimes this can be very useful. You can even use that to run your programs much faster. So for example, you can see right here, it runs faster than the older version. But the most important part is going down to the files right here and understanding if you have a Windows installer 64 bit or 32 bit, you can right click on my computer. And looking at that, select Windows installer 64 bit, and it should start installing. Now obviously because I already have Python, I'm not going to install it again, it's a very straightforward. Once you download the installer, you double click open the installer, click on, yes, yes, yes, yes, yes. All the way until you get this. You might see something like Add Python 3.9 path, or maybe it's 3.11 0.2 In your case, this is one of my older images. If you have this, you must check it. You check it, and then you continue because you do want Python added to your path. That's basically it. Thank you so much for watching. In the next video, we're going to be downloading Intellig and setting it up, and it's going to be the IDE that we use in order to write Python code. I hope you enjoy it and I will see you in the next video. Bye bye for now. 3. 2. Downloading IntelliJ IDE for Windows Linux Mac: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be downloading Intellij and setting a few things up. So first of all, what the heck is even Intellig, Intelli is Intellij idea. I think it's an acronym for something. I'm not sure what that acronym is, but it's an IDE. So what is the acronym for IDE? It's Integrated Development Environment. And what that means is that we're going to be using Intellij to help our computer understand Python language and compile the code that we want. I told you we have high middle level and low level. Some people just consider the high and low level. I tend to think that assembly is in the middle level of programming languages, IDE, IDE. What it does, it basically takes the high level, which is Python, because, remember, our computer does not understand English language. It only talks in two numbers, 0.1 Believe it or not, we're not going to go into software engineering and computer engineering. For now, let's just stick with what we have, which is Python and Intellij. Basically, Intellij takes the words that we've written in English and converts them into 0.1 sends it to the processor. The processor comes back with some information and we write it down. Or we get some kind of output or something like that. So, we're going to be using Intellig. Why Intellij? Because I found that it is the easiest, it's the most user friendly, It gives you a lot of suggestions very fast, and because it's free, we don't want to pay for anything. And in my experience, I found that Intellig gives you the best bang for your buck. So without any further ado, let's go ahead and download Intellij. So you should go to a website called Jetbrains.com When you go to that website, it should look something like this. If you can't find the Jetbrains.com for any weird reason, just simply type in Jetbrains on Google or something, and you should find the following page. Once you're here, you can read through everything. You can see that Jetbrains is not only used for Python, it's used for a lot of other programming languages. But for now we just need to go to the developer tools and we should have a dropdown. Okay, when we click on it, we have a dropdown and we need to go to Intelligdea. You'll see it here. We have different things, of course, by charm and so on, but for now, intelligent idea is what we need. We click on it. You should see a page like this right here. You can accept the cookies, you don't have to. Right here you can see intelligent ID, the leading Java and Plean IDE. Don't worry about that. Just click on Download. When you go to download, you will have this page. And I want you to be very careful because this one, the ultimate edition, is the free only for 30 days trial version. What we want is scroll down a little bit and download the community edition. So this is going to be the addition that we want. Now again, I already have intelligence on my computer. I don't want to download it again, but it's very simple, very straightforward. Download open the, the program E that you download. Enter, Enter, accept everything. But there's one crucial thing in here that you need to keep in mind. You might come up to a window like this where it will ask you to either create a 32 bit launcher or 64. Again, this depends on the computer that you're running. Click on 64 bit, make sure that this is clicked, and then you will come up to this data sharing click. Don't Send, because you don't want to send information unless you trust intelligent. I think they are going to take your information either way. I don't, I'm not sure they even ask for you to share your data, they just take it. But if you do get this, you don't have to share your information and that is all that I have to say. Thank you so much for watching. I hope you enjoyed. And in the next video we're going to be working on setting up Intellig for future the use with Python. So thanks so much for watching and I will see you in the next video. Bye bye for now. 4. 3. Setting up IntelliJ IDEA: Welcome back my fellow Python developers. In this video, we're going to be setting up tellg. The first thing you'll see is this layout right here. It might be a little bit different, but generally speaking, every vlog looks the same. We're going to click on New Project. In here, you should see the following screen. You click on Python and you should see Python 3.9 If you do see it, that's it. That is enough. You can continue to the next video, although I do recommend that you finish this one just in case there's something missing. Some of you might not see this because you haven't installed correctly or your computer is weird. What you can do is you can click on this drop down and you should find Python 3.93 0.11 3.5 15. I don't know whatever version you're on right now. But if you still don't see it, that means that your computer has not detected it yet. You can click on an Ad Python S decay. And now you have to go and find the location where this was saved. In my case, it was saved in C user ish. I called my computer ish whenever I got it. That was like four years ago and I was never able to change it. Next thing you need to do is right here. You should find the base interpreter. This should also be found just in case you don't have it, go and look for it. And finally, you need to make sure to make available to all projects and you can also inherit global site packages. And then in here you should click okay. But because I haven't made any changes, you should be able to click on that. And boom, there we go. And then when you're back here, you can click on next, you can call your project. You can select where you want to add all of your projects. Of course, find a suitable location, create a file for all the projects. And I do recommend if you have an SSD and not an HDD to save it in that SSD, it will help open up your projects much, much faster. That's basically, that is intelligent. In the next video, we're going to be creating our first Python code. Yeah, how fun is that going to be? I hope it is. By the way, you don't have to have the Z in search. I just typed it in because I don't want to reveal the privacy of my students and the projects that we've had together. Thanks so much for watching. As I told you in the next video, we're going to have first Python program created. So I will see you then. If you're still facing challenges in here, just please contact me or leave a question wherever you can and I will get back to you. But this is pretty much straightforward. I've never had any very bad, none of my students were very complainative, even a word, a word. Complainative about setting up intelligence. So I hope you don't face any issues. I will see you in the next video. Bye bye for now. 5. 4. Our First Python Program: Welcome back my favorite Python programmers. In this video, we're going to be creating our first Python program. It's going to be a very simple program. It's mainly for you to make sure that you've set up everything correctly. We're just going to look at a few minute small examples. Just a small, very simple print just to get you started, just to get over the scariness of Python, even though it's one of the simplest languages out there. But first of all, we need to understand what is the dot py file. As we said, we have Python, it was created by the Python people. We have another program that is Intellig. There is no inherent connection between Python and Intelligi. As you saw, Intelligi can be used to write Java, could be used to write SQL, it can be used for a lot of different languages. Python can also be written on other programming languages, on other IDEs, not just Intelligi. What is the connection between these two? How do we make sure that they communicate with each other while we do that using the dot py file. Whenever we create a new project, we cannot start writing code unless we create these dot py files. And you'll see that creating dot py files is a very easy, easy thing to do. So let's go ahead and get started. First of all, I'm going to go back into my analogy in here. I'm going to click on New project, make sure that you have the project as decay. Right here. You can see we need to copy and pace this into introduction. And then we will hit Finish. Boom. There we go. As I told you, the first thing we need to do is go to file new and create a new Python file that I will call Hello World and head Enter. Now we have Hello World. Now a few things about the py file name in here. I made a mistake. Usually when we want to name our dot py files, they shouldn't have any upper case letters and they shouldn't have any spaces. Now this will work. It's not a huge problem, that's why I did it. But it's customary to name our files in the following way. So hello, and either you type in world or you add an underscore in between them. It depends on your preference. And as I told you, using Hello World with capitalized letters is not going to break or re ruin your project. But later on down the line, you'll see that if you want to import a dot py file to another dot py file, you cannot have spaces and weird symbols. It will just not work. But anyways, look at what we have right here. You can see that we have the cursor blinking and we have line number one. And we can click right here and we can start typing stuff. Obviously, we're not here to type gibberish. We want to type something that is going to be useful. And the thing that is useful is going to be to type in print. And look at that. I want you to stop and look at the beauty that we have. This is why I love love Intellij. Because as soon as we start typing things in, we immediately get suggestions. And you can see that we have tons and tons of suggestions like print and property. So intelligent just puts it in the order that most people use. So for example, in here you can see that P R, the first thing that we get is the print. And I want you to get in the habit of auto completing things using the tab. And why use this autocomplete. There are many beneficial things that can come out of this. First of all, it helps you write faster code instead of typing in print and opening up the parentheses here. You just hit Tab, Boom, you have everything in front of you. Second of all, it helps you avoid any errors or any typos. So for example, print if you have a capital N, you'll see that we have an error. And that error is shown because of the red squiggly line. If I hover over the red squigly line, it tells me there's an error, unresolved reference print, because Python does not recognize print with an upper case, it only recognizes print with a lower case. The autocomplete will help us with that. Also, maybe you make a mistake with the syntax, for example, right here. Maybe you just forget to add the second parentheses immediately. You have an error if you have over the red squiggly line expression, expected or something like that, just an error using the tab helps with that as well. And finally, if somebody sees you typing in code and sees you or completing that code and typing, you know, like being in the zone, they'll be like am that person knows what he's doing or what she's doing please use the or complete. Get in the habit of doing it. It's going to be tremendous for your professional career. Let's continue on Inside of print, we need to provide it with some information to be actually printed out. If you're not sure if the print prints something, the name is obvious. You can always hover over this. And you can see that we were fetching documentation and you can read all about the print and the parameter that it takes. Of course, we're going to be talking a lot more about what the print is, how it's a function, what a function is. We have an entire section dedicated to functions. You can always read about it. But for now, all that we need to do is we need to know that we should provide it with something to say. And we should provide it with open up the double quotation marks and type in Hello World. Boom, there we go. Now if I write Click and I go to run Hello World, you can see that I get Hello World printed out in our console at the bottom. This is also something that I like a lot about Intellij, is that you don't need any external tools to run your programs. You just write, click run, And everything happens inside of Intellij and it's all controlled and it's all good. Now, why did I say hello world? Maybe some of you know this, maybe some of you don't. But when it's customary, whenever you start a new project or a new program, you always type in Hello World. Just to check like what's happening in the background. So there we go, that's Hello World. One last thing before we go. Like I use the double quotation marks in here around the Hello world. You might be asking, well, why? Well, because this is a string. And when we want to display a string in Python, we need to use either the double quotation marks or the single quotation marks. And I will be explaining more when we use double, when we use single, and when do we need them to be used together. Of course, all of that in the upcoming sections, but for now, if I remove the space in here, you'll see that I get a yellow squiggly line. So we've seen the red squiggly line. And I will be going over this again in one of the next videos. But when we see a red squigly line, it means we have an error. It means that our code is not going to run. So for example, if I type in print, I write click and I run. I get an error because the name print is not defined. But sometimes I might get these yellow squarely lines. So these are warnings, these are not errors. They might break your code, but most of the time they don't. So what is the issue in here? If we hover over it, you'll see that it's telling us a nine to no new line at the end. So what is step eight, P eight is how should I call it? Like it's the style in which the Python gods have told you to write Python code in order to make it clean. So one of the things that they require from you is to add an extra line at the end because it looks just better. You don't want to finish on just the code you want to finish on an empty line. So for example, if you add a space in here, you also get a small warning, please. Pep 82 oh two white spaces before the parentheses. We don't want that, we want to have it clean like this. Following the eight is a very good idea because if you show this code to someone, they will appreciate it more. If you ever go back to your code, you will like it more. And just having clean, easy to read, understandable, well organized code will benefit you a lot, trust me. Sometimes you go back to previous codes and you see all the gibberish that you wrote, and you'll be like, I wish I did it more correctly or had it better organized. But in any case, warnings such as these will not break your program. As you can see, we still have the same output. So I hope you understood. I hope all of that makes sense. And now it's time for a challenge. And what do I mean by challenge? Now I will explain and go in depth into what challenges are in the next video when I tell you how to use this course. But for now, you need to print out a personal message. This is something that you need to do on your own. So I want you to change the printed line from a simple hello world to say hello, and then next to it, your name. I want you to run the program to make sure it works. And I want you to congratulate yourself on your first Python program. Very nice work. So, pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? It shouldn't be too hard. You should only say hello Michael. You don't have to say Michael unless your name is Michael. Right click and run and it says hello Michael. And of course, you can't type in whatever you want in here. We can even duplicate this line using control D in here. I'm going to say thank you for watching, leave a review if you can, because at this point, maybe they've already asked you for a review. Wherever you are watching this or if you want, you can simply hit me up, like call me or text text me over what's up and tell me how you're enjoying the master class. I don't know why I wrote master with a small M and then are the one word. I'll just keep them as one word. So if I write click and I run. Boom, Ladies and gentlemen, thank you so much for watching. I really appreciate it. In the next video, we're going to be talking about how to use the scores, please. It's very important that you understand how to use the scores. I'm going to talk about the sections. I'm going to talk about the challenges and how you should do them. I will see you in the next video. Bye bye for now. 6. 5. How To Use This MasterClass: Welcome back my favorite Python programmers to a brand new video. And in this one, we're going to be going over how you can use this course. This will be probably the most updated video because I will keep adding new lessons, new techniques, new stuff to the course. This is the biggest master class anywhere in the world. I mean, I don't know if the entire world, but I'm pretty sure that this is top notch information. So first of all, this is your challenge slide. You can see that this is a slide inside of another slide. So this is slide seption or slide inception. Please don't click over the video. Continue with the on the master class, but anyway, this is your challenge slide. So when you see this slide, you need to pause the video and do the challenge on it. No matter how hard, no matter how much you feel that you are not able to do the challenge, it's imperative that you try and do your best because it's a much better way to learn. And because doing is much more important than just watching. This is the philosophy that I've built my entire career on, and this is exactly what I used to do in university. So maybe some of you have been through this. You sit in a class, you know the instructor just does some things, you know, some weird things. It doesn't have to be just programming anything like imagine math. You're looking at the instructor like solving all of these nice equations and you're like, yeah, this is so easy, I got this. You go back home, you open up the textbook, you start doing whatever challenges or whatever exercises. And then you find that you don't know anything or you don't know everything. At least because when the instructor is doing it, you feel that it's very easy. Because in your head you don't see the minute detail, the small thinking that the instructor needed to have. So that's why if you do the challenges yourself and you try your best, very best, even if you fail, you don't have to do all the challenges correctly. If you take at least five to 10 minutes of your time to try and do the challenge, to mess things up, to break your code entirely. And then when you see the instructor, even if it's me, or maybe you're doing one on one sessions with a specialized instructor that I've assigned to you. You'll see the process, You'll see the mistakes that you made. And you'll see how you can fix those mistakes. And more importantly, you'll understand why you did those mistakes and why we write the code the way that we do. Because sometimes is more important, not sometimes. I think almost 99% of the time, the why is more important than the how. Why did we have to solve this solution? Why did we write the code this way and not the other way? So when you make mistakes, you understand, oh, that's why get it. So please, whenever you see this window right here, you pause the video or wait until I give you some instructions. You pause the video and you do your absolute best. Let's look at the lessons structure. First of all, we have lesson number one, which is the introduction. This is like inception. We're talking about lesson number one and we've already almost finished lesson number one. You'll notice that throughout the course or throughout the master class, I will use this joke repeatedly. At any point, you can complain to me. But please don't leave me a bad review because of it. Lesson number two is getting started in Python. I believe in building a solid foundation. Some instructors like to just jump into the heavy duty stuff and start creating projects and whatnot. I like to build a solid foundation if you're trying to build a building. If you're trying to build the Empire State Building or whatever the bush, Kalifa for example. You don't just start building on sand. We have to go down into the very depth of the earth to find solid foundations. And then you can build the tallest tower in the world. And that's exactly what we do in lesson number two. We make sure that before we start writing very fancy code, we are getting started with Python. We are understanding the programming philosophy behind Python and other languages. You might find this lesson number two boring. It's not very exciting. But throughout the years, I found that the people that do build a solid foundation are incredible at moving forward with everything, with all the complicated stuff that we learn later on. Getting started in Python is the foundation building. Lesson number three is our first steps in Python. After building a solid foundation for like maybe 1 hour or 2 hours, we can now take our first steps are our introduction to blocks of code. It's going to be where we learn about debugging, we learn about if statements, We understand complex expressions like s and or ors, and we just look through. Different and variable testing areas in our code. Lesson number four is going to be loops in Python. This is our introduction to loops. A lot of people struggle in introduction to loops. We're going to be debugging our loops. We're going to understanding what loops are, We're going to see four loops over a range. Nested loops will be using brakes and continue, even though continue is not very well used. We're also going to be looking at why loops and how we can use L statements in there. Most importantly, this is where we are going to learn a binary search algorithm. As a future developer, as a future Python programmer, you should know what algorithms are. So we're going to learn a fairly simple algorithm. Of course, I will need your entire concentration in that section for you to properly understand what we're doing. But because once we learn our binary search algorithm, we are going to create our first project. It's a game, but it's going to be a project. And it's sort of an AI, but not a real AI. So don't get your hopes too high. But lesson number four, lesson number 12.3 are going to be very simple. Lesson number four is going to be the next step of evolution. Then we have data handling with lists and topples. This is where we are going to be introduced to sequence types. We're going to see mutable and immutable objects. We're going to be iterating over lists. We're going to be removing items. We're going to be adding items. We're going to look at nested lists. Lists inside of lists. So it's a list inception. We're going to be looking at nested data structure and we're going to also be creating a mini project which is going to be a car creator. Section number six is going to be our introduction to functions. You can start considering everything, section six and upwards as being slightly more advanced. We have the baby steps one to three, then we have the intermediate at 4.5 and then we have the slightly more advanced at level number six. Lesson number six is going to be the introduction to functions. We're going to be defining functions, setting up parameters, debugging our parameters, look at how we can call our functions, how they can return values, how we can handle invalid arguments being sent. And again, of course, we're going to have a mini project in our functions to get everything wrapped together. My favorite lesson is Less Or section is lesson number seven. It's object oriented programming in Python. I love this. If you want to take anything away, like please, if you at any point feel tired of the course and you want to give up, it's imperative that you get to section number seven. After that, you can stop. But lesson number seven is crucial. I cannot say it enough, because lesson number seven, If you can understand object oriented programming, if you want to learn any other language, it will take you a maximum of two weeks. You will understand what object orienting is. We will understand instances, constructors, and how to use self. We will work on class attributes methods and static methods. We'll learn about attribute accessibility. We'll learn about inheritance, polymorphism composition, subclassing, overloading a lesson number seven, very crucial, very important. Under no circumstances do you skip or you quit before lesson number seven. Then we have lesson number eight, which is dictionaries and sets in Python. Very important at data handling it, where we're going to be introducing dictionaries and sets. So this is the continuation of lesson number five, but I didn't want to have lists and couples and then dictionaries and sets right after each other because they are kind of slow, kind of boring, but very imperative. We're going to be learning how we can iterate over dictionaries. We're going to be creating a new mini project, and at this point, it's not called a mini project, it's called a project, which is going to be the computer builder. We're going to be creating and updating our values and dictionaries. We're going to learn about shallow and deep copy. And of course we're going to have an introduction to sets, so we're going to be erasing, removing, and discarding items from sets. We're going to create unions and intersections, and we're going to be creating subsets and supersets. Now we're getting into the more advanced part. Now we're going into reading and writing files. We're going to learn about opening reading and parsing text files. We're going to look at writing data to text files. We're going to learn about Json files and CSV files. And understanding dialects and sniffers and writing to CSV files. And looking at dict readers and dict writers. And see how we can use dictionaries with reading and writing from files. Very exciting. Complicated, but you need to go through it. And then we have lesson number ten. It's going to be the big daddy of all lessons. This is, at this point you're going to be learning a new language which is going to be SQL. So we'll learn about databases. We'll learn about SQL Lite. We'll learn about updating, deleting, ordering. We'll learn about database administration. We're going to learn about using SQL and database in Python. After we learn SQL, don't worry, it's not a very complicated language, but it's a different language. It's kind of hard at first, but then it gets very, very easy. We're also going to learn how to hack, which is very non ethical. But now it's going to be very simple and easy hacking. Don't think like we're going to be hacking any country, so just keep your expectations leveled when it comes to hacking. We're also going to introduce exceptions and creating a mini project that is going to be a bank account. And we'll also be creating Netflix. How about that? Not the actual Netflix, as I told you, it's going to be sort of a Netflix. Don't get your hopes to up. You're not going to become a billionaire after doing this mini project, but still, it's going to be very, very worth it. Ladies and gentlemen, before I leave you a few things that I need to say. First of all, I want you to take your time. I want you to go through every single section. I want you to be very thorough with your learning. If you ever have any questions, you can always ask your dedicated instructor. You can always ask me. You can always ask the community. So please, please, please. I want you to go through this entire course. Never give up. Try to do as much as you can during your day to learn every single thing. This is a very well structured. I took so much time to make sure that everything in the course, all the examples, all the mini projects, everything builds on top of each other. If you go through it step by step slowly, you are going to have tremendous and incredible results. If you go through this entire course, you will become a certified Python developer. You will be able to go into any interview, look them in the eye, and tell them that I am a Python programmer. And I thank Michael because he helped me and taught me. And I left him a review because I like him so much. And now I'm just kidding. If at any point you feel that you need extra help, you can always contact me. We can set up personalized one on one sessions together. And yeah, that's basically it. All I want to tell you is please don't lose hope. I want you to continue right now. Don't stop you, set everything up, it's time to get started. It's time to get your feet wet and start the first section or the second section or the second lesson, which is getting started in Python. You can understand strings, variables, data types, handling data. Also, thank you so much. I hope I didn't talk a lot. I just wanted to be thorough with my explanations about the sections and what you should expect. Hope you enjoyed and I will see you in the next video. By by far now. 7. Section 2 - Getting Started With Python | 1. Print() in Python: Welcome back my favorite python programmers to a brand new video and a brand new section where we are going to be kicking things off. The first thing we're going to do is we are going to create a new project right here in IntellG. Yours might be a little bit different. I stopped updating IntellG because sometimes the new updates get broken, the same things will hold true. The thing that we need to do is create a new project right here, select Python, go to Next and make sure that you select the proper place for this, and you can call this. Of course, you have the freedom to call this whatever you want, but I'm going to call this Getting Started with Python. This section is going to be all about the introduction, all about creating the environment and the philosophy of programming of Python programming. And seeing what happens under the hood to understand later on how things work in the end game. Throughout all of the sections that will be coming up. As soon as you create this, you already know you need to select the following thing inside of your project bar. Go to file, go to new, and create a new Python file where you'll be prompted to name this something and you can name it whatever you want. Of course, in here I'm going to type in the print underscore function and hit Enter. And there we go. Once you do that, you are able to start typing any code that you want. We're going to go through the print to understand how it operates and the different ways that we can use it. But before we do that, I need to tell you a little bit about functions and how they actually work. This is the typical function that you can see. It's a print function. Of course, we have an entire section dedicated to functions, but we're going to look slightly at this. First of all, we have the function name. The function name has to always reflect what this function does. For example, this is the print function. What does it do? It prints something out. Next we have the argument that is being sent to the print. What are we looking to print? We are looking to print hello world, for example. This is called the argument. And of course, as I told you, we're going to be seeing a lot more of this later on. And finally, we have the brackets. There are always syntaxes that we need to follow in any programming language, not just in Python. So in the case of Python, we need to use round brackets in front of the print where we are going to be sending the arguments. And even if we don't want to send any arguments, we should also still use the brackets. So let's go ahead and get started. I'm going to go back into Intellij, and in here I'm going to print out, Hello World. Now you might be wondering, why did I use single quotation marks? Why not use double quotation marks like I didn't here? Why do I use double quotation or single quotation marks at all? Well, because this is called a string and we're going to be explaining string variables more down the line, especially in this section. But whenever we are trying to print out a word or a sentence or anything that's in the English language, we use the quotation marks, indicating that these are letters that we are trying to print out. And we can use single quotation marks or double quotation marks. It does not make a difference except for, you'll see later on why sometimes it's better to use single or double quotation marks. For now, I will run this program and you'll see that we get Hello World Printed out. Let me close down the project. And let me duplicate this line of code by clicking at the end of it and hitting control D. As you can see, this line was duplicated. And I'm going to use double quotation marks instead of single quotation marks. And when I write Click and I run, I get Hello World again. Now you might have noticed that I added an extra line in here. And you'd be thinking, well, maybe Michael did a mistake. Well, Michael did not make a mistake. I am the God of Python program. Now I'm just kidding. I always make mistakes. But as you can see, when I removed the last line, I have a squiggly yellow line. If I hover over it, it tells me 292. No new line at the end of the file. What does that mean? First of all, what is P? Eight. And actually even before talking about eight, what is the yellow squiggly line? We have many different indications from intelligent that can tell us if there's an error, if there's a warning, if there's a big warning, if there's something that we need to look out for. And throughout the process of the course, we're going to be seeing all of them. But for now, let's talk about this warning. Now, this warning is not breaking our program. So if I write Click and I run even with the small warning, I still have everything working. But what it's trying to tell us is that we are not following the style that needs to be used to write clean and proper Python code. What does that mean? For example, pep eight is the version or. If you want to call it the gods of Python all sat down and determined that the best way to write Python code, to have it clean, and precise, and neat, and be able to show other people your code and for them to feel at ease when reading it is to follow the p eight rules. So p eight is the eighth version of these rules. And one of these rules is to add an extra line at the end of your program. It doesn't change anything, it doesn't break your code. It just makes it more pretty for other people to see and even for you to go back and look at it. So for example, if I add a space in here, look at that. Does that look clean to you? It's obviously something that's not really nice. And one of the more important things in this section and in this entire master class that I want you to understand, it's not only about how you write your code, It's about why you're writing your code the way that you're doing, and how to make it the best and cleanest version possible. Of course, we need it to work, but we also need it to be clean and easily readable for anyone that's looking at your code. It will go a long way. For example, in here, if I hover over this white space before the round brackets, we don't want that. We want to keep it clean and precise. If I, for example, add a space in here, again, all of this still works normally, but it just doesn't look nice. Imagine this code. It's not nice, it's not organized. It doesn't look pretty. We make sure that we write it in a correct way. Always follow the eight rules whenever you can. Let's move on. The print can do some other things. For example, the print in here can also print out a number like 84. Right click and run and we get 84. Notice that 84 in here is not a string, it's an integer, and we're going to be looking at variables more later on. A string is limited by either double quotation marks or single quotation marks while integer doesn't have these on it. Let me duplicate this again, control D. Instead of just typing in 84, I can type in 12 plus 13. If I write Click and I run these two numbers are added together and then they are printed out. You can do arithmetics inside of your functions as well. Let me duplicate this again, and this time I'm going to change this to seven and this one to 71. Instead of adding them, I will multiply them when I write click and I run. There we go, I get 497. Now you might have noticed that I left an empty space in here and you might have also noticed that it's not reflected in our console right here at the bottom. Why is that? Well, because empty spaces are not considered to be just empty spaces. They are considered nothing. It's just for organization's sake, I wanted to separate the string in the print from the integers and the numbers in the print. Well, now this begs the question, what can we do in order to create a space in our print out or in our console? Well, we can use print and then nothing at all. Now if I write, click and I run, there we go. You can see that I have a print in here. Now again, something that I just did and I still haven't explained to you. Look what happens when I start typing any letters. I start getting suggestions by intelligent. And this is a habit that you have to get into regardless of what you do going forward. If you want to become a good software developer, Python programmer, data analyst, anything that you do in life, always look for the Or Complete whenever you can hit Tab. As you can see, this completes for me, not just the words print or the letters in print. It also completes the syntax for me, which is beautiful, because there are three benefits to this. First of all, it avoids you causing problems, because, for example, if you type in capital N, this is no longer a working function. Look, we have a red squiggly line. And a red squiggly line means that there is an error. And it says it's a name error, telling us that name print is not defined. There's nothing that's print with the capital. If I hover over it, unresolved reference and it actually does break our code and look at the error that we get a link. If I click on that link, it takes me to the line where the error occurred. You can also look for the line right here. The autocomplete helps you avoid making mistakes such as these. Tab for autocompletion also helps you write code faster. And third and most important is that if somebody sees you typing in code and using the tab to autocomplete thing, they'll be like, oh my God, who's that guy? Or Gal. They are incredible programmers. They're using the autocomplete. Now, I'm kidding. This, it's not going to be that good. But still, of course, when they see you using autocomplete, it'd be like okay, this person knows what they are doing. So let's continue on. And now let's try to print something. So you can see I use the tab and I'm going to say this is the end. Then I'm going to add a comma in here. I'm going to say, nope, I was kidding. Add another type and three, add another. We are doing more. If I write a click and I run, this is what I get. First of all, I have the empty space from the print I did right here with no arguments being sent. And then this is the end. No pi was kid. We are doing more. What is happening in here? Well, we are providing multiple arguments to our function print instead of just having a single argument like we had in the hello world and hello world here, and the 84 and even this expression right here, it's a single argument because arguments are delimited by the commas between them. As you can see, because we've sent in multiple arguments, they were added together and then printed out. I hope that makes sense. Thanks so much for watching. Before we leave, you have a challenge to do, and your challenge is to combine everything that we learned. I want you to print out a line where you combine both words and numbers. Make sure to use the comma between them, so you need to send multiple arguments to your print function and run the code without any errors. Pass the video right now and go do the challenge. Okay, welcome back. So I will add an extra print in here and I'm going to say print. If we add 6.8 we get six plus eight, right click and run. And there we go. If we add 6.8 we get 414. Ladies and gentlemen, thank you so much for watching. In the next video, we're going to be learning more about strings and we're going to be looking at how we can get inputs from a user. So thank you for watching. I hope you enjoyed. Congratulations on starting this journey. You are amazing and you're doing incredibly well, stick with it. Make sure to give me your full concentration. If at any point you feel that you're a bit frustrated, you're not sure what to do, please contact your instructor that's dedicated to you or you can contact me. Of course, We you have my number. I have your number on Whatsapp or something. You can always do that. Before we leave, I just noticed something. We have the green squiggly line in here. If I hover over it, it's just a typo. The green squiggly line is not a warning. It's not an error, because sometimes the warning could be potentially an error. It's just a typo, for example. Now, there we go. No more typos. Thank you for watching. See you in the next video. 8. 2. Strings Variables in Python: Welcome back, my favorite Python developers. In this video, we're going to be looking at string variables in Python and also looking at inputs. Let's go ahead and create a new Python file by going to file new and then python file and we're going to call this one underscore variables in here. The first thing I'm going to do is I'm going to print out forest run between single quotation marks. Then I'm going to print out, Python is a really easy language to learn and between double quotation marks. Then I'm going to print out, we can include double cooptations inside our single quotations. Exactly. Double quotation. Of course, just to adhere to the rules of P eight, we add an extra line. If I write click and I run. This is why what I get run for run. Python is really easy language. We can include double quotations. But what makes this special? Well, let me try and duplicate this line. Instead of using single quotation marks on the outside, I'm going to use marks on the outside. And notice when I changed the one on the left, the one on the right automatically changed. And you already see that we have seven errors, seven freaking errors. What is the problem here? You'll notice that we have double quotations in here. Unresolved reference, double unresolved reference quotation, and then end of statement. Expected a lot of things going wrong in here, what the heck is happening? Well, you'll notice in here that we have a single quotation mark or the first double quotation mark, correct? So what Python thinks, and the way this works is Python, okay, is the print. All right, our programmer, our fellow developer is trying to print something out. All right, double quotation mark. Nice. That means there's a string coming. All right, the string coming, nice, character space space, I, N, C, L, D, E space. And then it finds another double quotation mark. And then Python thinks to itself, all right, there we go. The developer found the end of his string. We can close down the string now. But then it sees D and the D is not considered a string because we've, Python is thinking like we've already closed our string. What the heck is the problem here? Why do we have the D and then the o and then the U? Is this a variable that the user tried to create? Well, no. We were trying to add double quotation marks inside of the print, but it does not work like that. And then it saw that another string is starting. All right, this is the string and this is the end of the string right here. That is why if you want to use double quotation marks inside of your sprint or inside of a string where you have double quotation marks on the outside, you cannot. You have to use single quotation marks on the outside. The same holds true if we want to do it reverse way. For example, in here, if I try to change this to a single quotation mark, look at what happens. We have an error here because Python thinks to itself, well, this is the first string, this is the second string. I don't know what happened here. We just close things off. If you want to make sure that this works, you need to use single quotation marks on the outside and double quotation marks on the inside. Look in here. Because they changed automatically. This is how it would work. This changed again. Can you please just stop changing automatically? It's driving me crazy. Anyway. Single quotation marks on the outside, double on the inside. And can you please stop doing this? Thanks. Okay, there we go. Okay. I wanted to have single quotation marks on the inside. There we go. And in here, single, if it will allow me. I mean, the autocompletion can sometimes be a pain in the butt. But there we go. We finally were able to solve it. Of course, change this to single. That's why we have double quotations, and single strings can also be added together, for example, if I print out. Hello plus world. This is not called addition, this is called concatenation right here. When I write click and on, you'll see that we get Hello World. You might have also noticed that it's squished. Let me add just a print to differentiate between things. You'll notice that they are squished. Why is that? Well, because Hello world Don't have any empty spaces in them. The space is also considered a character in your string. You either have to add it in here or you have to add it behind world to make it work. Notice this is not using two arguments. These two are a single argument in here. If we add notes, we didn't have any space yet. Still, we created the space between these because these are multiple arguments being sent. While in here we are working with a single argument function, It's two strings that are added together and then printed out. By the way, we don't have to explicitly be using strings in here. When I mean explicit, it means when we use these two parentheses, or, sorry, dequotation marks, we can do something like the following. We can say that we have a variable that is equal to the message. This is a variable that I created and I call it hello there. Then I have name which is equal to Michael. Of course, you can add your own name. Now what we can do is I can print out message plus the name. And what do I get when I run hello there, Michael. Now, as a small challenge, I want you to create a space between these 23 to one. There are many ways of creating a space. I can add a space in here, I can add a space behind Michael. Both are valid, Both work fine. But there is even better way of doing this, and that is of adding a space right here so I can concatenate multiple strings together. So now we're going to have message space, Michael. Okay, I hope that is clear. Now, what if we don't want to have this created beforehand? At the end of the day, this is called a variable. Shouldn't it be variable? Shouldn't it vary? Well, it does, and it will. Instead of just having name equal to this thing that we want, we can say name equal to input. And inside of the input I can say, give me your name. I will just give a small indication. Okay, what is that? I will give a small indication in here to the user about where he should write the name. Right click and run, Hello World. Give me your name. You'll see that the program hasn't stopped. And now in here I can type in Michael. There we go. Now we were able to put any name that we want using the input function. And the input function takes in a prompt. So this is the definition of the function. We don't worry about this right now. We're going to be delving deep, deep, deep into these things in the upcoming section. But just so you know, this is a prompt, What do you want to print out with the input you need to give an indication to the user what they are trying to add. We're trying to add a name in here, for example. If I try something different, like for example, Kalen, there we go, a head and enter. It tells me hello there, Kalen. If I write, click and I run again and it's Santa Claus. That's how you write Santa Claus. I'm not sure. There we go. Hello there, Santa Claus. Okay, I hope that makes sense. As you can see, these are variables, and we can get input of these variables. We can cacateinate all of these together. Time for a challenge. Your challenge is going to be to print out your own input, create two new inputs for the user, from the user, a string and a number. We want one to be a string, the other one to be a number, and can catinate them together and print them out to our console. Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? First things first, add a print, and then in here I'm going to say print out, please type your name and a number. Then in here I'm going to say name is equal to input name, two dots. Duplicate this with the control D number number and then I'm going to print. And here I will say that I want to have name plus just eight plus number plus chocolate bars. There we go. I deliberately use double quotations and single quotations just so you know that we can interchange them in here. When I write Click and I run in here, let me just type anything. Okay. Hello there. Then please type in your name and a number. The name will be, let's just stick with Michael. The number is going to be 129. Hit Enter. So Michael just ate 129 chocolate bars, which is very bad. So I hope you understood how all of this works. Always try to do the challenges please. If you think that you cannot do the challenge, if you feel that it's too hard, I don't care. Just pause the video and try to do your best. It's much better for you to try to do your best. Fail at it, and then see the solution because your brain has already thought about things. It will help you learn faster. Learn better, clearly understand what happened and maybe some of the questions. If you just skip over the challenges, you might not even know what you don't know when you do a challenge and you fail at it. If you take like five to 10 minutes to do the challenges and you fail at it, at least your brain worked. You're not just watching me doing this stuff on my own. I'm a great programmer already. I don't need to do these. You're not here to watch me do this stuff. You are here to learn. So please, every single challenge, Pause the video. Do the absolute best that you can. And of course, at the end, leave my review, because I deserve one. Thanks so much for watching, and I will see you in the next video, where we are going to be learning about special characters. So I will see you then. Bye bye. 9. 3. Special Characters: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be looking at special characters. These are sometimes also referred to as escape characters, and these are special characters that allow us to do certain things to strings. To demonstrate this, I'm going to create a new Python file. Sometimes if you don't see the Python file in here, you should just simply click on the string variable or in the project, or not on the string variable like anywhere in the code inside. And then go to File New. And you'll find your Python file and I'm going to call this the escape underscore characters and hit Enter. In here, I'm going to create the split variable and I'm going to say that this split variable is equal to, this string, has backslash t, has several back lines in it. There we go, This string, see it catches it immediately. Very nice. And I will print out the split. When I write, click and I run, look at the output that I get. This string has several lines in it. Now you might be thinking, what does that matter? Like I could have done this. Okay, let's remove these s, we don't need them. We can write it like this. If I write, click now and I run and oh, oh, oh, okay. So unless you add the backslash n, which means a new line, that's why it has an n in front of it means new line. That is the only way that you can create the split. Now, there is another way, but not right now. Later on I will tell you what it is. So using the backslash n is how you create extra spaces. Now let's look at another example. I will add a print in here and then I will call this tabbed. Equal to this string is backslash. Tab. Backslash t several times. Tab is written incorrectly. Can you okay Tab, double B. All right. I think, there we go. And I'm going to print out the tab. All right. Click and run, and boo, look at that. This string is tabbed. Notice in here we have an extra space. It's stabbed to the front. Now, I think these are pretty self explanatory. There's nothing too much in here to say. Let's continue on and I'm going to write the following sentence. I'm going to say he was screaming, No, please. It was Jordan. He's the one who jumped notice in here, we have lots of problems. Some of you have already seen. Of course, if you watched the previous video and you should have, you'll see that we start with a single quotation mark. We have a double quotation mark, but then we have a single quotation mark which breaks everything. Then another single quotation then, so then double. It's all over the place. If we have a line that has double and single, some of you might have already asked yourself that question. What do we do? Well, we have the backs that we can add to this single quotation mark and to this single quotation mark, and to this single quotation mark. And now we have everything working right click and run, and boom, we have double quotations and single quotations inside of our string. The backslash allows us to have this output working neatly. I'm going to duplicate this line of code, and I'm going to change this from a single to a double quotation mark on each side. Let me try this again because it did not look clean. Double double quotation. And there we go. Now we have the problem on the inside. We add the backslash here and the backslash here. And if I write, click and I run, there we go, I get my output. And I don't even need or the backslash in here on the single quotation marks anymore because they are surrounded by the double quotations. All right, right click and run and everything works perfectly fine. So I hope you understood. I hope you are not too confused. These are the special characters. You're not going to encounter them too much. But please remember, we will be seeing them down the line. I will be using them. If I remember, I will tell you why we're using it. Maybe I won't. But after you've seen this, it's your responsibility to recognize them down the line. Before we move on. Aber of a challenge to print out a link. So print out the following link to your console using the print.python.org slash terminator slash, nothing else. Of course, I'm not sure, but I don't think this leads to anywhere. But I want you to print out the link. Nonetheless, the trick here is to print out the backslash. We're trying to print out the backslash. How would that work? There are two ways. One is very obvious, the second one is more tricky and needs a bit more research. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? I hope you tried your best to do it in here. I'm going to print out python dot or terminator back. Nothing else matters. As you can see in here, this is where the problems comes in. If I write click Run, this is what I get. Python.org and then terminator and else what is the problem? Well, I deliberately created this type of link in here because I wanted to have backs which created the tab. And then the backslash n, which created a new line. How do we fix this? The first way is to have a backslash to the backslash. Now, right click and run. And there we go, we have the link printed out properly. But there is also a different way. I'm going to duplicate this and remove. We can add an R at the beginning. As I told you, this will require more research on your part. But basically the R, make sure that we printed out as it is. Or it tells the function that this string should be printed out without special characters or to be more precise, the R stands for raw. You print out the raw string that you have in here, ladies and gentlemen, I hope you enjoy it. In the next video, we're going to be looking at variables and their types and we're going to be understanding better how these things work. Thank you so much for watching and I will see you in the next video. Bye bye for now. 10. 4. Variables and Types: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be talking about variables and types. First of all, let's try and explain what variables literally or actually are. Let's just imagine a box. Variables are like boxes. Imagine we have a box. That box has a name. The name is lives. What do we do with this box? We put in three inside of that box. Now we have a box that has three in it. The same concept holds true when working with variables in Python and any other programming language for that matter. In Python, we create a variable that has the name lives, so that is the name. And then we have the data that we want to put into that variable, which in this case would be three. Now, in Python, if you're coming from a different language in Python, you do not need to specify the type of variable. You only send in the data. And based on the data that you've sent, the variable will take the type of it. Let's talk about some different types of variable. First of all, we have the type float. For example, velocity velocity can just be two or three, or four or five. It can be 4.87 0.96 0.54 100.75 whatever that number is. It could be a float. Then we have the Ty bullion for example, if we want to check if something is dead or not, it can be equal to four. Is that can be equal to seven. It has to be either true or false. The bullion is going to be very handy in the upcoming lessons. And then finally, we of course not. Finally, we have many, many types of variables, but these are the most common ones that we're going to be using in the upcoming videos, which is the type string. It's a string of characters, for example, my name, this is the name of the variable. And then we have a string of characters. The characters are M, I, C, H, E, L, form together, string together, create the name Michael. Let's stop talking about theory and let's go ahead and take an actual example and see how all of that operates back in here. I'm going to create a new Python file that I'm going to call variables in here. I'm going to have age equal 25 and I will simply print out the age. Nothing too special in here. Just when we run, you can see that we get the number 25. Nothing too crazy, right? We've done this before. Let's now print out something slightly different and you'll get why we're doing this in a few. I'm going to print out the type of H. Now if I write click and I run, I get the class in stands for integer. These are whole numbers like minus one, minus two, minus 312340, et cetera. These are all considered integers. If I type in 25.6 for example, look at that. Now I have a flat, no longer an integer, it is a float. Now notice what's going to happen now. I'm going to add two single quotation marks, around 25. And I want you to look very carefully at what's going to happen. Look, when I write a click and I run, I get the same output, 25.6 But the difference is that now the class is a string. This is very important for you to know because sometimes things are not the same. Maybe you would think that, okay, 25.6 should always be a float, correct? This is the output. Look at that. You tell me, Michael, 25.6 we don't care. Is it a float? Is it a string? Who cares? You should care because a lot of things can happen down the line. So having the ability and the flexibility of changing the type of your variable by simply changing the data that you are giving to said variable is both a blessing and a curse at the same time of Python. So you have to be very careful when you change the type of variable or the data that you're sending to the variable, okay? The variable type will change with the data that you're sending. But if you're using that data in a certain way or that variable in a certain way, this can cause a lot of problems down the line. And we'll see a lot of those problems as we progress through the video. Now it's time for a bit of a challenge for you to do. Your challenge is going to be to create and print variables. First of all, create a float, an integer, and a bullion variable. Print them out using the print. Print out the type of each on a line, and make sure they all match what is given to them past the video right now and go do the challenge. Okay, welcome back. How did you get on with that in here? A print and then a number float equal to 70.4 b. Then we're going to have a t and we'll just have like 72. We're going to have a string. A string. And it's going to be, I love this master class and I will leave a review. This has nothing to do with what's happening right now. This is just off the top of my head. Okay. So yes, exactly. 55 star review. Okay. With a few exclamation, with a few exclamation marks. Okay. Just off the top of my head. And now we're going to print out the type of a number float, Duplicate this, a number, Duplicate this and a string. And the bullion of a bull. Sometimes bullions are referred to as bull, we'll just say true. Let's just also create one that's false since there are only two. A false false bull because you don't want to have the same name for two different variables, A, B, a false bull. Right click and run. As you can see, we have a float, a integer, a string, a bull, and a bull. Ladies and gentlemen, thank you so much for watching. In the next video, we're going to be looking at something that we need to watch out for, especially with our new found ability to change things. Thank you for watching. I will see you in the next video. Bye bye for now. 11. 5. Something To Watch Out For: Welcome back, my favorite Python programmers. In this video, we're going to be looking at something that can potentially break our program. What I'm going to do is right here at the top I have the H correct. I'm going to create another variable and I'm going to call it name. And I will say that the name is equal to Michael. Okay, so let's say I want to print something out to the screen and here I'm going to do that. I will first of all add the sprint and then above it I'm going to do the following. I'm going to print out the name and cactinate it with is, with a space on each side, plus age plus years old. This looks like a very innocent sentence. 25. Let's just make it 25 red click and run. And there we go. Michael is 25 years old. He needs a space in here. And now everything should look good. Correct. Michael is 25 years old. No problem anywhere except for, not 25 years old. But that's beside the point. The problem in here will come up if I try to do the following. Now look, even before we run, we already have a highlight. Now, we've never seen this highlight before. This is an expected error. This could potentially break our code. It's more serious than a normal warning. Always take heed whenever you see something like this. Now if I write Click and I run, I do get an error. And what does it tell me? It tells me that there was a type error and can only cactinate STR, meaning strings, not integers, two strings, the age was a string, we concateinated it, and then we decide, you know what, I don't want to have it as a string. I will remove it, and I will make it an integer. And Python allows you to do that. It's very simple, very easy. But these are the types of problems that we can potentially run into if we just try to change things out of our own will, please we, even though you have the ability to change the type of your variable whenever you can, Python gives you that ability and we're very grateful for it. But Python also considers you a grown adult. They consider that the person that's writing Python code should know what they are doing and should not do things like this. So please be very careful when changing the variable type. Thank you so much for watching. This was a quick video, there's not even a challenge in here. In the next video, we're going to be looking at number operators. So we're going to look how we can operate on numbers using different pluses, minuses, divisions, et cetera, et cetera. I will see you in the next video, and bye bye for now. 12. 6. Numbers Operators: Welcome back my fellow Python developers. In this video, we're going to be looking at number operators. We're going to create a new Python file that we are going to call numbers underscore operators. Boom. I'm going to create the first variable which is going to be a equals to 25 and B equals to five. Then I'm going to print out A plus B, double that. Then a minus duplicate that A times duplicate that A divided by B. Control D to duplicate just in case. And then A divided divided by B and then a percentage. This is also known as modulo, if I write Click and I run, this is what I get. 403-01-7057 0.0 7.0 These are pretty obvious. 35 plus five is 40, 35 minus five is 30, 35 times five is 175. I think the divided is a bit weird, because it gives us 7.0 Whenever you divide two numbers, even if both of them are integers, the return type is always going to be a float, unless you give it a second divided, which removes all the floating points. For example, if I had 35/4 you can see that I get 875. And then when divided divided, I get eight. It does not round to the closest number. This is a big confusion that a lot of students have. It does not round. It simply removes everything that's after the floating point. Even if you have let's say 9.99 9999, the answer is not going to be ten, the answer is going to be nine. Before we move on, let's go ahead and print out the type of a divided by B. Then the a divided divided by what do you expect the output is going to be? What do you think the types of these two are going to be like? Right click and run float and integer. Okay, I don't think there's too much to say in here. I mean these are pretty basic stuff. Just know that we can do arithmetics inside of Python using all of these different things without any further ado. It's time for a bit of a challenge for you to operate on these inputs, on the input, not these inputs. Get two inputs from the user. Use addition, subtraction, multiplication, and division. I apologize, I did not talk about the modulo in here. So the modulo gives us the remainder. So for example, 35/4 the remainder is three. If I have it divided by five, there is no remainder. Okay, so the remainder is zero. There's nothing that's remaining. 32/5 the remainder would be two, so it's the remainder what is remained after the division. Use addition, Substraction, Multiplication and division Research how you calculate the power in Python, for example, two numbers to the power. There is a small hint that you need to know and that is the int input. We are used to getting the input, but we haven't used the t on it yet. And you'll see why this is so important, Put the video right now and go do the challenge. Okay, how did you get on with that? So I am going to come in these two lines out in here. Instead, I'm going to say that a is equal to an integer input. Oops, Duplicate this input. There we go. Now if I write, click and I run, let's say 6.10 Hit Enter and boom, this is what we get. 16 -4,600.6 0.6 These are the various additions and divisions that we are using, something in here. Why did we have to convert it into an integer? Well, I'm going to show you. Let's say I remove this from here. By the way. The end, if you hover over it, it says creates and return a new object of the same type, or the integer type. Whatever you give it, it converts into an integer. What's the problem in here? The problem in here is that we've already learned that we cannot concatenate two different types. Meaning that when you get the input is a string. That is why we have to convert it into an integer because a is an integer, when we do a plus B, it does not work. We've already seen that in variables. Right here, you can see H does not work. You cannot concatenate a string, an integer, with a string. And the same happens in here. We get the input a, we convert it into an integer, and then we are adding it to B, which is an. Should be an integer. But now, because we don't have the int function around it, it stays a string. And the same holds true for a minus B. Now, a times B does work because you can multiply a string with a number. I will show you that in later videos. We also cannot divide, of course, and we cannot take the module. It's very important that we do have int around our input in order to be able to convert it 52.10 we get these outputs. Now last part, research how to calculate the power. Now some of you might have found some function, some of you might have found it easier than others. The easiest way is to simply add an extra star in here. And this actually creates, let's try numbers. Boom, there we go. This is 14 to the power three, or a to the power. Now, before I move on, there is something that you need to know, and that is that, just like in regular math, we also have operator precedence when working with Python. For example, in here, if I do the following, if I print out a plus B divided by three minus three multiplied by four, we all know that the division and the multiplication go before the addition and subtraction. Now if I write Click and I run and I get a to be equal to 2.1 you'll see that the answer is -9.666 Why? Let me try this again to pick some easier numbers. Let's pick three because it's divided by three minus nine. What happened? We have three, this is one plus A, this is three. Minus three times four. We do three times 412 minus the three that we have in here. So we get minus nine operator presidents. Precedence also applies in here, but we can change it using parentheses. I can add parentheses around three multiplied our, actually, this doesn't make any sense. Let's add parentheses around A and B. Now, the answer was minus nine, when we had 2.3 Let's strike this again. 23. Boom. There we go. We had minus nine. Now we have -10.333 Why? Because two plus three is 5/3 I have no idea. Minus three times four. There we go. We can add parentheses to change things around. Thanks so much for watching. I hope you enjoy it. And in the next video, we're going to be looking at string data types. We're going to be delving deeper into strings and what they are. Thank you for watching new. 13. 7. String Data Type: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be looking at string data types on surface. Strings might be very simple to you, but strings have something hidden deep inside of them. Let's go ahead and get started to explore what these hidden secrets of strings are. First of all, I'm going to create a new Python file that I'm going to call string data type. I always add an underscore inside of my file names. You don't have to add it sometimes when you can have spaces inside of your files. But if you want to import these files to a different file, you cannot unless they have underscore in them. The best conventional way is to use underscores and to have no upper case letters. I'm going to hit Enter. In here, I'm going to create the following message. I'm going to say the message is equal to, Python is a great language. Python is a great language. In here, I'm going to print out the message. Pretty simple. I don't think there's going to be any confusion here. When I write, click and I run, I get Python is a great language. Perfect, I just printed out the message. But did you know that I can access individual characters using the message? I can print out message at position number two. Let's look at what's going to happen if I write, click and run. I get. Now where did this come from? Well, if we look right here, we have P y. Now you might be thinking, well, is one, y is two and is three, but I used two in here. How does this work? Well in Python and in most programming languages, when you want to count something, you start at zero. Here, I'm going to add a common. This is a common, by the way, when you have a hash tag, this is zero, then 12345. Look at that. At position number two, I have, what would I get? For example, at position number four, I can hear you in the back saying I get o and you would be correct, you get, let's continue naming these 56789. And then I'm going to add another level of comments that will be in here. For example one, and then 012-345-6789 and then 012345. And here I will add a one, sorry, two. Now, if I tell you what would be the number or what would be the character at 16, what would you tell me it's going to be because it's 16. Well, now, if I tell you 11, what will be the answer? Oh, nothing. It's not, it's actually a space. The space or the empty space is also considered to be a character. This is what the string hides under its surface. It's called a interval. When iterable is a item or a data type such as lists, topples, dictionaries, sets, and lists, also ranges. We'll see all of that in upcoming sections. Don't worry about it for now. Just know that you can go through your string using indexes. These are called the indexes, the on the zero, the 11, When you are able to access them using the square brackets. These are indexes. Okay? So I hope that's clear. I hope it's not too hard, because I want you to really understand it before moving on to the challenge to print out a message differently. So I want you to use the message that we have to print out another message. And that other message is going to be, you are hot using the indexes of your original string method. So pass the video right now and go to the challenge. Okay, welcome back. How did you get on with that in here? In order to print out U are hot, obviously we need to find the Y, O, U, et cetera, et cetera. So I'm going to print out message brackets, and then let's start with the U. The U is at one plus message, the O is at four. Then plus message, the U, we need a U, it's at 22, plus message, we need a space. A space could be found at six. And there we go. Excellent. I'm going to hit enter in here. And don't worry, this is not going to break anything. It will stay the same in here. Message, open this up, you are A, we need an A. Where's the A? It's at ten plus message. We need a U R. We need an R. Where's the R? At 13:13? Plus the message to 213. Where's the other U R? You need an E, it's at 14. Let's see what we have so far. Practically can run. Okay, you are excellent. Now again, we need to have a space with the six. Now for the hut, I'm going to find the H, which is three plus these four, plus the message at 02:16 Right the click and run and there we go. You are hot. Thank you so much for watching ladies and gentlemen. I hope you enjoyed. In the next video, we're going to be looking at negative indexes, so we can actually go through this going backwards. Thank you for watching and I will see you in the next video. Bye bye for now. 14. 8. Negative Indexing in Strings: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be looking at negative indexing in strings. Just like we have positive indexing, where we use positive numbers, we can also use negative numbers. Let me show you what I mean. First of all, I will select all of these lines and hit control forward, which will comment out everything. Again, select all of these. Hit control forward if you ever want to uncommon them. You can also hold down control forward slash while selecting these lines of code. Control forward slash. And now in here I'm going to print out message at position minus one. What do you think the answer is going to be like? Well, if you said it's going to be E, you are correct. Once we start indexing, going backwards, we start going from the end of the message or from the string to the very beginning, for example, minus eight. What would that give us? Right click and run. I have no idea. I generally do. Don't I mean, 12345678? Yes, exactly. So on the L, so for example, if I wanted the, I would do minus ten because this is minus eight. Minus nine. Minus ten. So right click and run. And there we go. We get the, so we can do negative indexing. Pretty simple. Nothing too much in here. I think you get it. I don't think there's too much complications with how this all works. It's exactly like using the positive indexes. It's just negative the other way around. So with that out of the way, it's time for a bit of a challenge. Your challenge is to print out the message differently. So I want you to use negative indexes to print out the same message. And that message is, you are hot, but I want you to print it out now using negative indexes. So pause the video right now and go do the challenge. Welcome back. How did you get on with that? A lot of you might have went through this in the very hard way. Meaning that you want to find, for example, the Y. You have to count it all the way to the Y. That is probably the non cheating way, but I have a cheating way. I already have these messages in here. Let me actually copy this. Mm hmm. And based it in here. And some of you who spent a lot of time on this are already angry because they feel that there's an easier way of doing this. The easier way is since we already have 26 characters in here. And why do we have 26 characters? Because we start at zero and end at 25, which means we have 26. What I can do is I can add -26 to this immediately. Now I can calculate it, this is -25 or you can use a calculator for example. And I calculate Ok, 13 -26 et cetera, I get -13 it will be -13 and here it will be minus minus. But I can keep it as it is, so I can keep the equation inside without having to change anything. And I will, you are hot using negative indexes, I have a problem -13 -26 is out of range. I'm so glad that I actually got this problem. The issue in here is that I can maximum, for example, in here, let me, let me just remove this and show you that this actually does work. Okay, there we go. You are hot. The problem is if I go to -22 for example, what do I get? I get the O, so I'm right here. If I go -25 right click and run, I get y, that's great. -26 I get correct, Everything is good. But if I go -27 I am now outside of the range of my string. So I am again, There's no more minuses where I can go. And the same thing holds true if I try to go in the positive direction. So I know that the last index is 25, where I get, but if I try to go 26, I am now outside of the range and this no longer works. I hope you understood. Some of you might not have even heard the last part. Some of you might have clicked off. And now you're like, you know what, I don't want this course, I don't want this master class. And you're using the slur words that I'm not going to repeat in here because of what I didn't hear. Some of you had to calculate all of this stuff, or some of you might have found this. I have students that did find this equation on their own. So congratulations to those who did. Those who don't feel bad, You still have a lot of challenges ahead of you where you can prove yourself in them. So thank you so much for watching. I hope you enjoyed. And in the next video we're going to be looking at slicing strings which is using the indexes not to extract only a single character, but to extract, extract an entire slice out of your strings. So, I will see you then. Bye bye for now. 15. 9. Slicing Strings: Welcome back my favorite python programmers to a brand new video. In this one, we're going to be looking at slicing our strings. Let's go ahead and get started. I'm going to create a new Python file in here, or actually we can stay in the same file. No need for a new file. I'm just going to comment all of this out and then start a new. I'm going to print out the following message. Open up the brackets, and this time I'm going to say zero, column five. Now when I write Click and I run, I get the word pytho. As you can see, this is called a slice where I have the starting and then I have the end that I want. Now you might be saying, wait, five is the end. Is the end. Why do I not have an n in here? Well, that's because the rule here to keep in mind is that it's up to, but not always. Keep that in mind when working with almost anything in Python. It's always up to, but not in up to, but not including if I wanted to have Python. What should I write in here? Yes, I can hear you. It's six. Now I get the full word Python. And notice that there are no spaces in here. Let's look at slicing just in a more theoretical way. Here we have the string that we want to slice, we have the start stop and the step. We haven't seen the step yet, We're going to be seeing the steps in later videos, but for now, this is the starting index, this is where we start slicing, this is the stopping index and it's not included. And then we have the step through, what are the steps that we are taking? For example, right now our step is one because we're going y H O. And you'll see we can use a step of two, for example, to have instead. We'll see all of that in later videos, but for now, let's focus on using the slices. Without these steps, it's hard enough to understand the slices, the steps right here message. If I do the following 12, 17, what do you think the output is going to be? If I write, click and I run, I get the word, great. Because I start at 12 and I stop at 17. There we go. And no spaces in there. Now my question to you is, what would I print out if I type in the following? What do you think I get? If I write, click and I run, you'll see that I get the word by thumb. Why is that? Well, when you don't specify the beginning or you don't specify the end, you simply start from. Then if you don't specify the beginning, you start from the beginning. And if you don't specify the end, you just go until the very end. So I hope you understood, I hope it wasn't too hard. I'm going to issue you a challenge where you will have to print using slices. So print out the word language by slicing our string. And there are two methods of doing it. So pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? We need to use slicing. Some of you might have used the regular extraction of variables of using the indexes. No, we need to use slicing. It's pretty simple. I think message in here you have to go from number 18, right, because we start at L, L starts at 18 or the index of L is at 18. And then we need to go until the end. So I can go 25, right right click and run and oh, where's the E? 25 does not work well in this case. I can use 26 even though I got an error on 26 here, if you remember. But when using slicing, it is manageable. Now if I go 27, as you can see, I still have everything. The slices isn't as bad. Let me try, for example, 30 and I write Click and I run, boom, there we go. I still have language when using slices, there's no worry of going outside with the index. That is the first method, 18 to 26, I get the language. The other method is 18 and nothing because as I told you, I can go until the end when I write click and I run. I also get a language when I don't provide the beginning or I don't provide the end. I simply start from the beginning or I go until the end before we move on. I still have a few tricks that I want to ask you. A few quizzes if you'd like. For example, what would I get if I do the following message column 18, plus message brackets 18. What do you think the output is going to be? Well, if I write Click and I run, I get Python is a great language. Why is that? Because in here I start from the beginning and I go until 18. In message, I start from 18 and I go until the end. I hope that's understood. Quiz that I want to ask you. What would we get if I do this just a column? Well, some of you might have answered that we get the entire message. It's because I start from the beginning and I go until the end. Thanks so much for watching. In the next video, we're going to be slicing using negatives, which is going to be a bit of a headache, but it's going to be very important for us to get used to everything that's happening under the surface in Python. Once we finish this section, you're going to have a very solid foundation, not just for Python programming, but for programming philosophy in general. So thank you for watching. If you have the time, leave me review. Wherever you're watching this or you can just contact me. Tell me, hey Michael, like I don't get anything about this master class, please. Can you help me I'm like, yeah, of course What's the problem? I don't know why I said that. Thank you so much for watching and I'll see you in the next video. 16. 10. Slicing with Negatives: Welcome back, my favorite Python developers. In this video, we're going to be looking at sliding using negatives. Again, I am going to comment all of these out and I'm going to start a new. Now you can see that we have a lot in here, but still we are going to be using the same message. So it's worth staying in the same file. If you want, you can dissect it into multiple files. You can do whatever you want. As long as you keep everything neat and clean. If you ever want to go back and look at your files from time to time, let's go ahead and get started. First of all, I want to print out the message from -14 to minus nine. What do you think the output is going to be? If I write, click and I run, I get the words, great, how is this working? I'll start from the end. 123-45-6789 101-112-1314 -14 is at great. And then 123-45-6789 minus nine is at seven, which is the space right here, -14 to minus nine is the slice that gives us great. Now what would happen if I, for example, do -14.4 bit weird, right? If I right click and I run, I don't get anything that is because -14 is right here on and four is right here on A. You might be thinking, well maybe that's not the problem. The problem is that you just can't use negatives and positives, but you can if you do -14 17 is right here. Right click and run. You get the word. Great. It's not about that you cannot slice from a negative to a positive. It's about, you cannot slice going backwards. For example, I cannot print out the message from, let's say nine. I mean 19 to, I don't know, 15. That is not possible. I cannot go backwards unless I use a step that we're going to learn in the next video. But for now you cannot going backwards. You don't get anything printed out. But if you, for example, let's say I start at minus, just like I have in here. -14 is at 17 is at the space. I'm not slicing backwards, I'm not going back. I sing forward, I cannot slice like this. I can only slice like this from left to right. I can slice from right to left. I cannot slice and that is the only rule. Before moving on, you have a bit of a challenge to print out using negative slices. Print out the word language by slicing our string. But this time you can only use negative slicing. And a small warning that there are a few traps in here that you should try to avoid. Pause the video right now and go do the challenge. Welcome back. How did you get on with that in here? If I try to do the following, I'm trying to print out the language. Some of you might have been tempted to do the following. Minus eight and then minus one, correct. The only issue in here is when I write click and I run is I do not get the E. So how do I solve this? Well, there are two ways I can. For example, use 00 is right here. If I write click in Iran, it does not work. Why is that? Well, because the way it operates is it thinks that we are at minus eight right here on the L. Then we're trying to go backwards. So does not work. That is the second trap. Now the last solution or the only solution is to actually do the following from minus eight until the end. And when I write Click in Iran, I get the entire language. So thanks so much for watching. I hope you enjoy it. And in the next video we're going to start using the step in order to slice. And I will see you in the next video. Bye bye for now. 17. 11. Using a Step while Slicing: Welcome back my favorite Python developers. In this video, we're going to be using a step while slicing. Finally again, I will comment out, I'm going to start from the beginning. In here I'm going to, excuse me, print out message and I will start from zero, go to 17, and use a step of two. I will then duplicate this, and I will use a step of three. So what do you think I am going to get? Some of you might have thought about this, some of you might have already used this. And I'm very proud of you. So when I write Click and I run, I get po saget and ga. My pronunciation of these ancient symbolic words is going to be weird. But what's happening in here is that I get P, Y. I'm using a step of two. And when in here I'm using a step of three, I'm skipping over two letters in here, I start with Y, H, O, and space IS space, that's why I have two spaces in here. Then I skip over the And space and I get and then skip over the R and E and get A. So that is the basics of having steps. Now with that knowledge, and by the way, when we don't specify the step, we just default to one and we just get the normal step. Let's now find a useful use of these steps. I'm going to create a new file and call it the data coming in here. I'm going to have data underscore underscore N, And it will be equal, it will be equal to 63548. You don't have to write the exact same numbers. Semiclumn 6957 forward 3267, multiplication 48 to 926, square bracket 36 14. And then finally we will have the plus sine and 406-70-9907 I mean this is data coming in, but as you can see, we have corruptions inside of it. We have, we have multiplications, we have weird symbols. What we want to do is we want to create a filter. What we'll do is we want to extract all of these separators and print them out. Okay? So that then we can use it as a filter in order to filter out all the bad and negative things in here. So what I want you to do is I want you to do the following. To print out the separators. I want you to print out the separators. I mean, I don't know why I have that point in here. Use steps in slicing to avoid the numbers. So pass the video right now and go do each challenge. Okay, welcome back. How did you get on with that? First of all, I will print, obviously, data coming in. And now we need to understand what the slices will be. Where do we start? Some of you might have started at zero, but it's not at zero where we want to start. We want to start at one. Why is that? Because we want to, first of all, catch the comma, then to where do I want to go? Some of you might have counted how many characters we had in the string, but there's a much easier way, and that is just going until the end. Now the final question is, what step do I need to use? Well, if I start here and I want to skip over four letters, it means that the step should be five. Now when I write click and I run, you'll see that I get all of the symbols printed out. And now I can use this filter in order to put it on the data coming in. And if for example, I find this parentheses or this one or this one, they will all get wiped. So ladies and gentlemen, thank you so much for watching. In the next video, we're going to be looking at slicing, but this time we are going to be going backwards with the slicing. So I will see you then. Bye bye for now. 18. 12. Slicing Backwards: Welcome back my favorite Python developers. In this video, we're going to be looking at slicing backwards. And it will be the last lesson about slicing, hopefully. So let's go ahead and get started. First of all, I'm going to create a new Python file that I'm going to call back underscore slicing, and I will, because Intellij froze, I will use the power of editing to see you in just a few seconds. Okay, welcome back. Letters equal to A, B, C D E F G H R J K L M N O P R S T U V W X. As you can see, look how helpful IntellG is. I forgot X, Y, and Z. So if I write Click Show context, okay. It just tells me that I forgot a few letters. So Y and Z. No, there we go. Now what I want to do is I want to create a variable that is the reverse. It's equal to letters. And now I'm going to start at 25, go until zero, and have a step of minus one. What will this do? It will start from the last one and then go to zero. With a step of minus one. It will reverse the letters. If I print out reverse, if I write click, you'll see that I get Z, Y, X, U, T, S, Q, Q, P, O, N, L, et cetera. But as you can see, we have the A missing. How do we solve this issue? You should know by now. Come on, I know you know it. What do we do? We'll remove this in the middle. And now we're right click and we run and we get the A. Why did we not get the A when we use the zero? Because it's up to but not including, we don't include A in the beginning. I hope you understood how this works. This is the basics of it. This is slicing, going backwards, when we use a negative step. We've looked at indexing, we've looked at slicing, we've looked at slicing using negative indexing. We've used steps, and we've used negative steps. As a final challenge to this entire new concept, I want you to print out the following three. I want you to print out IJK using positive steps and indexes. Positive steps, positive indexes U TSR. Using negative indexes, I mean negative steps or the step should be negative, the indexes can be positive. Then the last eight characters in reverse order using negative index and a negative step, okay? The last one is the most important one, negative index and negative step. The second one only negative steps. And the first one using positive steps and indexes positive video right now and go do your best. Okay, welcome back. How did you get on with that? First of all, we had a print and then I will create IJK equal to letters. And this should be pretty easy. We simply go from IJK. Wait, let me just double check. 12345678. Wait to 012-34-5678. Yes, eight until 11, and we print out. Ijk. Ijk. There we go. Very nice. Now, let's do UTR and it's going to be equal to. Now, we said that UTS R should be using the negative step. It means that we are going backwards since we only need to use positive indexes. So this means that we have 0123, 4567, 8910, 1112, 1314, 1516, 1718. 1920. We start at 20 and we need to go back four steps, which means 16, I will have letters and we're using a negative step, so we start at 20, go to 16 and it's not included and minus one. Let's just check if this is correct. Uts R, right click, Run. There we go. Very nice. And why is it telling me in the word typo? Okay, no worries. A typo in the word. Finally, we need the last eight characters. We want to have the last eight characters with a negative step, with a negative index. How are we going to do that? So first of all, we need to go to the end. So we need to get to that, we need the last eight characters, so 12345678. Okay, so first of all, let's set the negative step minus one. So I am going backwards. That means I need to start at minus nine and get to the end. No, I need to get to minus nine in reverse order. Okay, Now it makes sense. In reverse order. Step minus one and a negative index minus nine in here. And we want to start at the beginning. If I print out the last eight characters, right click and run, There we go, 12345678. All right, so ladies and gentlemen, thank you so much for watching. In the next video, we're going to be looking at a few string operators and we'll see how we can print out numbers with strings and we will be done with this introductory section. Thank you for watching. If you're enjoying the scores, leave me a review. If you're not doing the challenges, this is the time to start doing them. Thank you for watching and I will see you in just a few seconds. 19. 13. String Operators: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be looking at string operators. Just like we have operators format like the plus, multiplication, division, et cetera, we also have ones for strings. I'm going to create a new Python file and call it underscore operators here. I'm going to create string number one, String one, which is going to be equal to one space. I will duplicate this a few times. We will have string 2345 in here. I will say does not simply walk into Mordor. If you're familiar with Lord of the Rings, you might know this mean. If you're not, I'm sorry that I'm such a geek, then we're going to print out string number one. And actually, I'm not sorry for me being I'm sorry for you not having watched the movies yet. String number two, string number three, string number four, and string number five. These are strings being concatenated and we've already seen what happens when we run. You can see that we form a single sentence, which is one does not simply walk into. Now let's add a print in here to separate the lines, and let's do the following. I'm going to say, hey, there my name is Rodo Baggins. As you can see, we are not providing multiple variables or multiple parameters to our print in here. Unlike what we did, for example, in this case where we had a comma between each of our parameters being sent to the print in here, there are no, this is a single variable in here that's being sent. So when we run, you can see that we get the following. We do need to add spaces in between in order for this to be readable. As you can see, if we want to print multiple strings next to each other, we don't have to add a plus. They just get added on their own, or they get concatenated automatically. We can also use the multiplication. So for example, in here I can print out string number five multiplied by three. And what do you think the output is going to be? Think of it for a second. Right click. And I run, I get mordor, Mordor, Mordor. You can multiply the number three times. I mean, you can multiply a string by a integer. Now, what do you think the answer in here is going to be? Well, you might have already seen that we have a highlight, which means that we will probably get an error. If I hover over it, it says that it expected STR, meaning string, and got integer instead, limited by the end. If I write click and I run, I get the error telling me that you can only concateinate a string and not an integer to a string. This is an integer and this is a string because the multiplication happens before. How can we fix this? Think of two ways that we could fix this. 321, I can add parentheses in here. Now, the three plus six is going to be equal to nine string five multiplied by nine, we will get to nine mods. That's one more mordor than we should have. Now the other way of fixing this is we can change the six into a string. Now when we right click and we run, we get more mod and then six added to it. Okay. Now we could also do this in a slightly different way. I will duplicate this, I will cut, put it at the start. Add plus to it. And what do you think the answer in this situation is going to be? I want you to really think about it and write it down in your head before you actually run the program. Right click. And we run, we get six mod mod mod. The multiplication works before the addition six is added at the beginning. But then only mordor is multiplied three times. I hope that makes sense. If we wanted to have the six also multiplied with mordor, then we would have to do something like this. And now we get six mod six mod six mordor. That's just too many modors. Before we move on, there is one more thing that we need to understand in here, and that is that we can print or in string five. This checks if we have or inside of string five and returns a bullion. If I write click and I run, I get true because I do have or in more door. See I actually have two Ors. Now let me check if I have an but this time with a upper case. What do you think the answer is going to be? If I write Click and I run, I get false. Why? Because the characters, when we talk about string references should be the same as they are in the string. For example, the upper case is not present or the upper case is not present in mordor. That's why it has not been detected. Let's now try something else. Let's try do in string five. What do you think the answer is going to be? It's also false even though we have D, and then, and then, and then R. But they are not in the same sequence that we are looking for. They don't form the word door in here. I hope that makes sense. Finally, we're going to print, print out and check if rain is or in My name is Michael. What do you think the answer is going to be? If I write, click and run, you'll see that rain, unfortunately, is not in Michael, even if I tried to add rain like this. So notice I do have rain, but I have a space in between them. What do you think the answer is going to be? Is it going to be a true or a false? It is still a false because the space is also considered a character. The only way to get a true in here is to actually have the word rain somewhere in our string, and now we have it as true. Thanks so much for watching. I hope you enjoy it. And in the next video, we're going to be looking at how we can embed integer numbers into our strings and print them out. Because currently you've noticed that we cannot do that. We cannot concatenate numbers and integers. But there is definitely a way of solving this. So thanks so much for watching. I hope you're enjoying the lessons. We are almost at the end of the section, so I will see you in just a few. Bye bye for now. 20. 14. Printing Numbers: Welcome back my favorite python programmers. In this video, we're going to be looking at printing numbers. And when I say printing numbers, I mean the ability to be able to print integer numbers with strings. So let's go ahead and get started. First of all, I'm going to create a new Python file in here that I'm going to call printing underscore numbers. I'm going to create a variable that is numb, underscore of underscore rings. And I will say that it's equal to three. And I will print out the following. I will print out there were plus number of rings, rings forged by Sauron. There were three rings forged by Sauron. If I right click on, of course I get an error. I already had a highlight. I should have seen that coming. I cannot concatenate an integer with a. Now, there are many ways of changing this. We can, for example, add the single quotation marks around the three in here. But as we've seen, this is a risky maneuver. You don't want to always be able to change the type of your. There is a different way we can convert this into a string using the SDR method. Now when I write it, click and I run. I get there were three rings forged by saw. Looks like this works, not bad. The only issue in here is that using the SDR every single time you have an integer that you want to print is not very feasible, it's a bit of a pain in the butt. We can use something called replacement fields. Let me show you what that is. I will control D to duplicate this line and I'm going to there were replacement field. This is called a replacement field with a zero inside. Then at the end of the string I will type in format num of rings, the number of rings, the squiggly bracket. Zero, squiggly brackets is a replacement field and it replaces whatever we have in the format. Now when we use a zero, we replace the first one. Right click run, there we go. There were three rings. This is much easier than using the SDR right here. Much faster. Now if you only have one item that you're replacing, you can actually use this right click and run. You don't have to indicate that you're using the zero. Now let's go ahead and try something else. I will duplicate this. Instead of using the format, I can directly inside of the replacement field, type in number of rings. But it's very important that you hit the tab in here. Why? Because it adds a small F at the beginning, which means that the replacement field is actually going to be useful in here. If we don't have the F, this does not work. This is the output that we get. You need to actually have an F at the beginning of the print and then print it out. And this is, by the way, something that's fairly new. You'll see me using it later on down the course, but I might also use the format. So these two ways are very important to know. You might see other people use the format. Some situations the format is better than the, at the beginning of the string, but it depends on the situation. You can use the F, you can use the format, use whatever you want. Now let's go ahead and look at the following. I'm going to add a print in here, just a empty line, and I will print out there were replacement field zero rings made, one for the elves, seven for the replacement field two, and replacement field three for the men. Then hit enter again, format, and inside I will have 19, because in total there were 19 made, the number of rings, then dwarves, then nine. Now, what will happen is we have an index in the format, 19 is at zero, number of rings is at one, dwarfs is at 2.9, is at three. When I write click and I run, you'll see that everything was replaced properly. Now we can add a space in here. Notice that even though we add an enter, the new line does not get created in here. How do we create a new line? Of course you remember it's the back, it's the special character, but we don't want to do that right now. As you can see, this works. Now why do we use numbers? We could have just had the following. And notice if one of them uses numbers, everybody has to use numbers, or none of them have to use numbers. So when I write the click and I run, you'll see that I get the same output. So why use the numbers in the first place? Well, let's say you wanted the words which are at position three being used at the beginning. So you can type in, for example, two and then you want to have 12.3 Now when you write Click and we run, you see that there were dwarf rings made doesn't make sense, but I'm trying to highlight to you how this works. For example, let's say you wanted nine. You wanted this item that's in the third, or it's in the fourth position, but at index number three. So when I write Click and I run, there we go. There were nine rings made. So that's the power of using replacement fields. As I told you, you can either use the format or you can use the variable name directly through the replacement field. And the F at the beginning choose the methods wisely. It depends on the situation. And when you're done with understanding how all of this works, it's time for Aber, a challenge for you to print out the days in a month. I want you to use replacement fields to print out the number of days corresponding to the month. Only use three replacement fields, and what do I mean by that? This is an example of how this should look. You should have January 31, February 28, March 31, et cetera, et cetera, et cetera. And then you also need to, or if you want, you can print it out in this way. Depends on the situation. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here I will add a print. I'm going to do the following. I'm going to print out January replacement field, February replacement field, March, March, April, May, June, July, the month of Julius Caesar, August, and the month of Augustus, maybe I don't know, September and October, November, December. And I will just separate these so that the line is not too long. Boom, boom, boom. There we go. Now, at the end, I want to add a format. So we will have a 31, 30. And of course, 29, 29 is for February, correct? And in here we have an error. And what does it tell us that too few arguments for the format string. All right. So it wants us to add the replacement field. So first of all we will have two for February because it's the only month that has 29 days. Then we have January with 31. I think this is January 31. Yes, I think it's 31. So this is going to be zero. What other month do we have a 31? Wait, let me check. We have January, March, May. Let's do these. January, May, and then July, July, August, October and December, July, August, October and December. And the rest will have. Once, there we go. If I write click and I run, I get exactly the output that I wanted. Very nice. I hope you were able to do this challenge on your own. Now let me copy this because I want to show you something very neat. Now, you could have went around and just added a back to create a new line, and that would have been correct. You would have been correct in doing so, adding a back to set every single month on a different line. But there's a small trick in here that you can use and that is using three quotation marks around it. So the three quotation marks will actually produce the exact same thing that you're trying to write. What I mean by that, if I write, click and I run, look at how my output works. Looks, it looks exactly the way I had, I had said it intentionally. So right here, look. January, February, March, April, January, February, March, April. And then we have May, June, July. And you'll see that it's even pushed. So I'm going to remove these single quotation marks. And let's also add a print in here. Using three quotation marks will produce an answer that's exactly like the one that you are looking for. Let me move January and these to the same line. Okay, there we go. Now we still have February. Actually, we will just add an answer right here at every single month shift tab to go backwards, let's right click and run, and look at how this looks. Okay, very nice. Shifting back, right click and boom. There we go. We get the same outputs. Ladies and gentlemen, thank you so much for watching. I think this is the end of the section. Maybe later on I will add more videos to the section. Who knows, we'll see, but I hope you enjoyed. I hope you took your time to understand everything that we've done. Some of these things are not going to be super useful down the line. We will not be using everything that we learned here, but this is a crucial section where you will build your foundation for programming to later on go to harder and harder things. In the next section, we are going to be taking our first steps. We're going to be understanding blocks of code. We're going to be understanding if statements. And these are going to be the essential building blocks for your path and your journey to Python programming and becoming a Python developer. Thank you so much for watching. I hate to say it again, but I have to. I shamelessly plug the ask for a review if you're enjoying the course. If not, continue watching the course until you enjoy it and then leave my review. Thank you so much for watching. I hope you enjoy it. Hit me up. You send me a message. Tell me, Michael, what Upman like. I'm liking the scores. I'm enjoying the stuff that I'm learning. It would make my day. It would really do. Thank you for watching. See you in the next video. Bye bye for now. 21. Section 3: Taking Our First Steps | 1. Introduction to Blocks: Welcome back to my favorite Python programmers, to a brand new video and a brand new section. And in this section, we're going to be taking our first steps, even though we've already kind of started, but we were just getting our feet wet. We were just understanding the philosophy behind the programming and how things operate in Python below the hood. But now we are actually taking our first steps and understanding Python programming. And we are starting with blocks of code. First of all, we need to understand what blocks of codes are. In fact, like many programming languages, Python uses blocks of code to program their language. Python design philosophy emphasizes code readability. This is something that I've told you in section number one, where I was introducing you to Python. Python uses indentations instead of brackets to the limit code. If you are familiar with any other programming language, you might recognize the squiggly brackets that are used in order to define where a block of code begins. And you might have reduced those squigly brackets in many different languages such as Java or C Sharp, et cetera. But in Python, we don't require blocks of code to be determined or to be delimited by squiggly brackets. We can simply use indentations. And I will show you what I mean by that. Well, what do I mean by that? Let's say we are working with a block of code. If you are experienced with different languages, blocks of code begin and end with these squigly brackets. For example, we have a four loop. This is a four loop extracted from a C Sharp or Java. And you can see that we start with this block of code, and then we end with these squiggly brackets. Or we start with squiggly brackets, we have the block of code inside, and we end with a squiggly brackets. This is the other languages, Python, we have something different, we use these two indentations right here. As you can see, this is the four loop, of course. In the next section, you'll see that four loops are written differently in Python. But this is just an example. So this is the code that we want to execute, and these are the indentations that we use in Python to limit our blocks of code Without any further ado. Let's go ahead and start taking some examples to properly understand what we are talking about. In here. I'm going to go to file new and create a new project. I'm going to call this project. Of course, select where you want this project to be created. In here you can call this Getting Started. You can call this blocks and statements. I'm going to call it, actually, let's make it more specific. I'm going to call it blocks of code in Python, and then we are going to finish this window. All right, looks like we are good to go. Make sure to select the project right here. Go to file new, and I'm going to create a new Python file that I'm going to call block, underscore and underscore statements. So the first thing we're going to do in here is create a four loop. Now, don't worry, I don't expect you to understand everything about four loops, but this is going to be a very useful tool for us to properly understand where the block of code starts and where it ends. Just follow my lead, and don't worry in the next video, In the next section, I mean we will be expanding a four loops and loops in general. First of all, I'm going to type in four in ran, the range will be 1216 and then hit Enter. Notice when I hit Enter, I don't go back to the beginning of the line. Look where I go. I am tabbed, I am indented in here. I will print out and add an extra space for the P eight. Notice what I have in here. I have something called an indentation. This is the indentation I told you about when we were talking about the structure of a block of code in Pipa. If I write click and I run, this is the output that I get. I'm going to talk this right here to the right. You see I go one through to 15. Basically what this line of code in here means. It means that for I in a range of 116, I want to print out, I start with I equals one, I print it out. Then I go back, I make I equals two, and then I printed out, I go back, make I equals three, printed out 456, et cetera, until we get to 15. And you'll learn more about ranges in the upcoming section. But for now, all that you need to know is that it's up two, but not including, we go up to 16. But. It's not included. Now let's continue on and let's look at if we do the following. If I hit another enter from this print line, you'll see that I am still indented. So I can type in print and then in here I can add just a dash and I will multiply it by 20. What do you expect is going to happen? Please, just take a few seconds. Think of the output before you actually run it. Boom, there we go. Just like we've had with the eye, at every iteration, we are printing out these 20 dashes that we've seen before. We've already seen how this works and the getting started. That's why it was very important for us to build the foundation in the first or the second section to be more specific, that is, our update. Now if I write the following, I print out, hey I indented. What do you think the output is going to be? Notice that this line is no longer indented. It is not part of this block of code. What do you think the output will be like? If I write, click and I run, look at that. Hey, I'm indented is only printed out once. Why is that? Mm hmm. Why is that? Well, because it's not part of the block of code. It's no longer inside of the fore loop, so it's on the outside. So it just behaves like a normal line of code, not as indented or as part of the block of code that's in this fore loop. But for example, if I Tab, it hit Tab when you click on here and then hit Tab, it will get indented. So now if I write click and I run, think of the output. Yes, exactly. There we go. As you can see, we've added an indentation and then we print it out at every iteration of our four loop. I hope you understood how a block of code operates in Python. Now it's time for a bit of a challenge. And your challenge is going to be to explore the code, use the code I've written for you to play around with it, and go wild in your exploration. Add indentations, remove indentations, try to add a few more print lines, see what happens, play around with the indentations, see how it affects your code, Pose the video right now and go do the challenge. Okay, welcome back. How did you get on with that? Let's try a few things in here and just try to break out our code. For example, if I hit Shift, tap on the second line. Look at that. If I try to write, click and run, it tells me that there is an unexpected indentation. If I click on the link and it takes me to the line, it's on line number four, MI in. There's an unexpected indentation. Because Python uses indentation to delimit the blocks of code, we cannot just add indentations for the sake of adding them. They have to be precise. They have to be concrete in indicating where the blocks of code begin and end. The problem with this is that I already had a block of code right here, print, then I removed the indentation, so the block of code ended right. But then I had another indentation, so that is no longer correct. When we stop inventing, that's where the block of code ends. So for example, I can do this, but I cannot do this because I stopped the block of code. I ended the block of code for this four loop when I stopped the indentation. So I need to have an indentation. Now, what would happen in this case, Again, if I right click an iron? You've already seen the error. You've already seen the squiggly red line. We cannot do double indentations. You'll see later on we can indeed do double indentations when we are working with nested if statements or nested loops. But for now, just for the sake of this example right here, as you can see, we cannot add double indentations if I remove, hey, I'm indented. And if I print out hello, what do you think the output will be? And I will add also an empty print. As you can see, hello is printed out at every iteration. Ladies and gentlemen, thank you so much for watching the next video. We're going to be looking at if statements, which is a very exciting place to get started. It will really begin to form your skills in programming. Thank you so much for watching and I will see you in the next video. Bye bye for now. 22. 2. if Statements: Welcome back my favorite Python programmers. In this video, we're going to be looking at if statement. If statements are going to be a continuation or a more practical use of blocks of statement. So let's go ahead and get started. First of all, let's look at the structure of an if statement. We have if some condition, so we're not sure what this condition is right now, but we are going to have some kind of condition if some kind of variable is greater than a certain number or whatever condition there is. So if some condition is true, this condition has to be true. Then we will create a block of statement that will execute. Again, only if this condition is true, we will execute that block of code. But we also have something called the L, where if this condition is not true or is not satisfied, then this block of code will execute. And you'll notice that we always have the indentations right here. Again, you'll see what this or what these conditions will look like. But for now, just understand that if we have some condition in here that is true, we will execute the code that's inside. And again, we're using a block of code, or blocks of code delimited by indentations right here. Let's look at an example to properly understand. And then I will take you back and show you the structure again back in our code in here. Let's go ahead and create a new Python file that we are going to call if underscore statements in here we are first of all going to take an input. We're going to say age equal to an integer input, because we want it to be an integer. And we're going to say, hey, there Mr. Potter, how old are you? So this is going to be our input. And we'll also indicate that this is an input using this little indicator here, right? So that the user knows exactly where they should be adding their input. Age equals whatever. And then we are going to simply print out the age. This is just for debugging purposes, just so we make sure that everything works correctly. Right click and run. Hey, Mr. Potter, how old are you? Let's say 18. Hit Enter. Boom. The answer is 18. Great. But now let's go ahead and create an if statement or a line of code that will only execute under a specific condition. I will remove the print H, we don't need it anymore. This was just for debugging purposes. And when I say debugging, I mean just so we make sure that our program works correctly, I'm going to say if age is greater than or equal to 17, then I'm going to print out, welcome to the party Harry. I should write. Well, come not with 15 mistakes in one word. Now let's look again at the structure. If some condition, and then we have the block of code. Notice the indentations. Oh my God, can I get to my code if the age is greater than or equal to 17? Look at this block of code. We print out, welcome to the party it's greater than or equal to. That is why we had to convert our input into an integer because if we hadn't, we wouldn't be able to compare a string to the integer. I will show you what I mean by that, but for now, let's right click and run. Hey, Mr. Potter, how old are you? 21. Hit Enter. Welcome to the party. Harry Only because we have 21 as the input, it's greater than or equal to 17. We can go to the party. If I write it, click again, I run again. For example, I type and 12, I hit Enter. Boom, there we go. We don't get anything. This is a conditional if statement, only under a certain condition. Which in here is if the age is greater than or equal to 17. Does this work? Let me show you what I mean by greater than or equal to. We can just have greater than. If I write, click and I run and I type in 21, again, this works perfectly fine. But if I try to run this and then if I type in 17, note is 17 and I hit Enter, I don't get anything. Why is that? Because we only execute if it's greater than 17. 17 is not greater than 17, it's equal to 17. And our condition in here, if age is greater than 17, we need to actually add this equal sign. And now if we type in 17, there we go, We are welcome to the party. Great. But what would we do? Or what should we add in here, just in case we get a output in case we are not greater or equal to 17. Well, that's where the L statement comes in. We've already explored the L statement. We talked about it. It's simply added right here under the L. Notice it's not indented because it's not part of the block of code. This is the block of code. This is the L is part of the entire if statement. Right here, we type in print out, sorry Potter but but your two or actually, you're not old enough for the party as you can see, because we have a little single quotation mark in here. We have to add a backslash in order to be able to print it out correctly. There we go, everything looks good. We add the extra line for the P eight and then right click and run. Now, how old are you if I type in 12 and hit, but you're not old enough for the. If I run this again and I type in 25, hit Enter. Welcome to the party Harry. Now again, one last thing before we continue on in here. We need to know that we can actually add multiple lines in here. We can say here have a want also. Okay, so this is a block of code. We can have as many lines as we need in each one of these blocks of code. If I write Click and I run 18, boom. Welcome to the party here. Have a want also, and you can add as many as you need. So I hope this is clear. This is an introduction into if statements. These are crucial. Every single language that you will ever encounter will have If statements in them. So take the time, make sure that you understand what is happening. If you want to play around, play around, change the condition, see what happens, and then move on to the challenge. Your challenge is going to be to create your own F statement. Create an F statement that checks if the age is 17. Do it right below our current condition. Print out a message and create an L statement. Print out another message in that case. And what I want you to do, I want you to get the same message as in the first conditional statement. And notice I didn't say I want you to write the same message. I want us to get the same message. What I mean by that is in here, I will just get you started with the challenge. So I will print out, for example, in here, a few dashes multiplied by 20. Then in here I will want if statement statements. Statement with the L, et cetera. What's wrong in here? I forgot the All right, the if statement with the Ls and et cetera. And I want to get the same output when I run right here. Okay, let's say we type in 18, Hit Enter. I want under these dashes to have the same out. Welcome to the party. Harry here on the condition should be less than 17. You need to know how you need to change your code when you have a different condition, but we still want the same outcome. That is the goal. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here, I'm going to remove this. I'm going to say if the age is less than 17, I will print out the following line else I will print out these two lines. Now if I write the click and I run, how old are you? 18, boom we get the same outcome. If I write the click and I run and type in 12, boom we get the same outcome. How is this working? In here we check if the age is greater than 17 or greater than or equal to everything, 18 and upwards is welcome to the party. If they are not 18 or upwards, they are not welcome to the party in here. We do the same thing, but this time the condition changes. So now we check if the age is less than 17, then we say, sorry, Mr. Potter, you're not allowed. If it's less than the same idea holds true, but it's written in a different way, and this is very important that something very important that you need to understand. We want or we are able to have the same output but have different code. And you'll see that even though we get the same output with different code, there are codes that are better than under codes. And we'll explore that in the next video. But for now, I hope you understood this is not too complicated. If you're not sure how this is working, think of it logically, go back through it, understand it properly. Take your time. You're beginning to build your foundational skills in programming, so it's okay if you're not understanding everything 100% correctly, just take your time, do the examples, redo them, continue through the section, and I will see you in the next video. And if you're enjoying the video, please leave me a review somewhere. Just hit me up, You send me a message like, hey Michael, I'm loving this. Just like Mcdonald's. See you in the next video where we are going to look at lip statements in statements me. 23. 3. elif Statements: Welcome back my fellow Python programmers to a brand new video. In this one, we're going to be looking at elyph statements. Let's look at an eliph structure. Let's say we have some condition. Condition Number one, if the condition is true, then we will execute the code. We've already seen this in the previous video. Should be pretty obvious. But now what if we don't want to just create a statement if there is nothing else true? What if we have some other condition like condition number two, L? If some other condition number two, then we will execute condition number two. If condition number one is not true and this code executes, we start off with the first condition like we've saw before. If the condition is true, we execute this code. If the condition one is true, then some other condition which is number two. If that one is true and condition one is not true, we will execute the following code. Let's go back into our code and let's see how this looks in here. I'm going to add in here, Alif, we have g equal to 150. I will print out, oh, and by the way, equal needs two equal sines. Because one equal sine means that we are assigning a value to a variable. Two equal sines means that we are comparing two values. Lip age is equal to 150, we're going to say, and I will add double quotations. Dumbledor, you're too old for this party. That's how you write Dumbledor. I think so. Now, I'm going to copy this, and I will add it in here as well. Notice now what we need is we need this condition to be not true. In order to execute this line, of course, we need this one to be not true, and we need this one to be true in order to execute this line of code. If I right click and I run, and if I type in 150 and I hit Enter, you'll see that we have a discrepancy in here. Now, we do get, sorry, double door. You're too old for this party. But we only get it in the second conditional statements, meaning that we get it in the second F statements right here. While in here we don't get anything. Why is that? Well, let me tell you something about how the LF operates and something that you need to always watch out for when working with multiple LF statements. Right here at the top, let's look at the logic. The logic says that if the age is greater than or equal to 17, we will execute this block of code. Now, what is the age? The age is 150, correct? So 150, is it greater than 17? Yes, it is. A is 150, it's greater than or equal to 17. This entire condition is true, which means that we print out welcome to the party, have a want. Also, when one condition is true, that's it, we simply jump out. We don't continue going through the lips, We don't continue going through the Ls. And this should be obvious from the way that we are framing the if the furthest condition is not true. Let's go back to the structure. If condition number one is not true and condition number number two is true, then we will execute in here. It works. Why? Because we are first checking if the age is less than 17. If it's less than 17, we print out, sorry, you can go 150. Is it less than 17? No, it's not. So this condition is not true. We go to the Alif, we check, is the age greater than 150? Yes it is. So we print out, sorry, umble door, you're too old. If I right click and I run, and I, for example, try 180, hit Enter, it tells me that I am welcome to the party in both conditions. If now I type in 50 hit Enter, it tells us that we are welcome to the party. And if I type in 12 hit enter, we are not welcome at both parties because we are under aged. So this is just making sure that everything is working correctly. So for example, at the 12 mark, I check if the H is greater than 17. No, it's not. Is the age equal to 150? No, it's not. So I go to the LS and I print out, sorry, you're not old enough in here. 12. Is it less than 17? Yes, it is. So we print out, sorry, Mr. Potter, you're not old enough And then we don't even check anything else. That's it. One condition is true. We go through it, boom, we exit out. This will be more obvious in the next video. When we are going to be working with debugging and intelligent, you'll see how each and every single line of code executes. But now it's time for a bit of a challenge. Your challenge is for you to create your own Lip statement inside of our two statements. I want you to check if the age is greater than 600 using an Lip inside the statements that we already have. Print out a message in that case and do it for both of our statements. I want you to check if the age is greater than 600 positive video right now and go to the challenge. Okay, welcome back. How did you get on with that? In here, I will add an lip age greater than 600 and print out, you must be Nicholas Flamel. I think this is how you write Flamel. Wait, let me Google search. I hope you know, and by the way, I'm using these references and I hope you have an idea of who Harry Potter is. If you don't, that's okay. No worries. Nicholas Flamel? Nope. This is how you write it. I just Googled it. Oh my God. Can I please copy this? Yes. This is how you write Flamel. All right. I will copy these two lines and put them in here. Shift tab, right click, run. If I type in 800, hit Enter, the first one does not work, the second one does work again. Why is that? I want you to take the time to understand it on your own, and this works only in the second one, because A is equal to 800. In here we check if the age is greater than or equal to 17, 800, Is it greater than or equal to 17? Yes, it is. So this condition is true. We print out, welcome to the party and we jump out of the if statement. We go to the print in here, we check is 800 less than 17? No, it's not. Is age equal to 150? No, it's not. Is age greater than 600? Yes, it is. Which means that we print out, you must be Nicholas Flamel and we jump out. We don't continue until the L statement. Ladies and gentlemen, I hope you enjoy it. In the next video, we're going to be delving deeper and we'll see how we can debug an intelligent which will help us a lot throughout our journey. You're going to be debugging all the time, where no matter how long you stay with Python, debugging is going to be part of your journey and it will help you tremendously throughout your learning path or journey. So I will see you in the next video. Bye bye for now. 24. 4. Debugging in IntelliJ: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be looking at debugging in Intelligy. This is going to be a very important lesson, a very important tool in your arsenal that will allow you to carry on learning in a much better way and going through iterations of your code to understand how it properly works. So let's go ahead and get started. First of all, you need to add something called a breaking point. This breaking point is where your program will stop executing and stop at that exact point. So you can see right here between the code and the number of lines that you have, there is an empty space. For example, I can click on this empty space to add this red dot. This is called a breakpoint. If I hover over it, does it say anything? No, doesn't. But trust me, this is a breakpoint where it suspends the thread. So it stops the code from executing. Let me show you what I mean. I added the breakpoint right here, correct? On the first if statement, I right click and I debug if statement. And as you can see, we have something different happening now. I'm asked, how old are you? Let's say I hit 150 and I hit Enter. And look at that, I'm not executing the code yet. There's nothing happening. There's no output yet. The debugger. Let me close this down and let's work on the debug. You'll see a long blue line. This long blue line indicates which line we are currently at in our debugging process. Currently, we are on this line we are trying to evaluate. You can see also all the variables that we have. For example, right now we only have one variable which is an integer, which is age, which is 150. You can also see it being displayed right here on the actual code in gray. You can even hover over it. Click on it, Set Value. You can change the value if you want, if you want to play around with values and change them up and see how program would respond in that situation. But for now we are evaluating if age is greater than or equal to 17. When I step into, you can see that I have many buttons in here, but the most important one is going to be the step into, which is seven. If I step into Boo, you can see because this condition turned out to be true, we evaluated it, turned out to be true. We go into this line of code which is welcome to the party Harry we step into again, here have a want. And now look at what's going to happen when we step through this again one more time. As you can see, we jumped out of the entire if statement. So we glanced over the lip, we glanced over the age, we glanced over the Ls and then we went directly into the print in here. I will step into again, look at the console as well. Look at the console now. We have welcome to the party Harry here, have a want. If I step into again, now we've printed out, we've executed this line of code and we printed out our dashes. Let's continue now. We are checking if h is less than 17. If I step into and notice H is 150, 150 is greater than 17. It's not less than 17. So what happens? We simply jump over the print. We do not execute that block of code. Now we're checking if the H is equal to 150. Yes, it is. So we go inside of this line of code, sorry, double door. You're too old for this party. Now, what will happen when we step into again, I want you to tell me before we execute or we step into as you can see, we finish and we print out, sorry, double door. You're too old for this party. And what you should have known is that we will not go through this Lyp, we will not go through this else, we will simply jump out. Let me show you another example. For example, in here, let's say I type in 12 in here, hit Enter, and we step in. Okay, we stop right here in the execution. What will happen now with the blue line? I want you to tell me we have 12. Is 12 greater than 17? No, it's not. So we go to the next teleph. Is the age or 12 equal to 150? Now it's not. So we step into and we go to the next elif. We check is age greater than 12? Is 12 greater than 600? Now it's not. So we step into, but now focus on what's going to happen. What we usually did, we checked if it's greater than we stepped into the lift and we stepped into the next lift. But when we are working with the Ls, we don't evaluate anything on the Ls. Look at where the line is going to go, but we go directly to the print. There's nothing to evaluate if the first condition was false and the second elyph was false and the third elyph was false. We can add as many elyphs as we want. If all of these were false, we don't check anything on the Ls. We simply jump into the Ls and we execute the code there. Now as you can see, we didn't have anything. We step into, we execute blood line of code, it works. We step into, again, is age less than 17? Yes it is, and we have the same output. All right, well, good. So I hope you understood what's happening. Now it's time for a bit of a challenge. And I want you to test out the debugger throughout your code and make sure you understand how breakpoints and debugging work. For example, right now I want you to try and see what happens when our age is greater than 600. And try before you use the debugger, always try to imagine how the code will execute in your head and then go through it, posit the video right now, and go do the challenge. Okay, how did you get on with that? Now for example, if I remove the breakpoint I added in here on this print, if I write click an ID bug, for example, I type in 800, hit Enter on the console. You'll see that I already went through this entire if statement and I only stopped when I got to this print. This is what the breakpoint does. It only stops the code on this line of code, on the line that we've indicated for the code to stop doesn't stop elsewhere. Let me put it back at the top. And debug this again. We can see what happens. So let's type in 800, hit Enter. Is 800 greater than 17? Yes it is. So we print out, welcome to the party. Boom, we print out, here have a wand, and now we print this out. Let's check 600. Is it less than 17? No, it's not. We go to the next lyp. Is G equal to 100? No, it's not. We go to the next lip. Is H greater than 600? Yes, it is. So we print out, you must be Nicholas Flamel, And when we finish with it, we simply jump out and we don't need to go to the else. So ladies and gentlemen, this is a very crucial lesson to understand. The debucker is going to be a tremendous tool in your arsenal to make sure that you properly see all the variables properly, see how your code is working. You'll be using a debuger no matter what you do in life when it comes to programming. So please take the time to clearly understand what's happening. And I will see you in the next video where we will be delving deeper into conditional statements. So bye bye for now. 25. 5. Deeper Into Conditional Statements: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be delving deeper into conditional statements. To better understand conditional statements, we're going to be creating a game. And it will be a guessing game where we are going to be trying to guess Nicholas Flamels, age. Let's go ahead and get started. We're going to create a new Python file in here that I'm going to call Nicholas underscore Flamel. Underscore H. Boom. First of all, we're going to create the actual H which is going to be equal to 665, then we're going to print out what is La Mel's age, Wesley, and then give him the old indicator. Then we're going to get the guess which will be equal, or actually we don't need this one. Since we're going to be getting the input on a second or another line in here. We're going to have the input which is going to have the sprant. Of course this needs to be an integer because we will be comparing it to some numbers. We're going to be creating the statements in here. If guess is less than the actual H, we will print out, run guess higher then elif, elif. The guess is greater than the actual age will print out. Please run guess lower. There we go. How will this work? Well, it should be obvious if the guess is less than the actual age, which is 600, we are going to tell run to guess higher please. If it's greater than the actual age, we will tell them to guess lower. If I right click and I run, this was debugger right here, we can close it down. What is f age 12? Please run Guess Higher. Click and run what is flames age 1,000 Please run Guess lower. All right, looks like our code works correctly. The only problem is if I type in 650 and hit Enter, still tells me to please guess higher. Interesting. What is the matter in here? I'll wait. I apologize. 665. Hit Enter. I don't get anything because we actually got the right age. 665 is not less than the actual age and it's not greater than the actual age, it's equal to the actual age. And we don't get any answers, we don't get, hey, congratulations, we don't get points for Griffendor. What is the problem? The problem is that I still haven't given you your challenge to do what if Ron gets it right? So print out a message of congratulations if Ron, guess it correctly, past the video right now and go do the challenge. Okay, welcome back. How did you get on with that? Some of you might have just printed out this in here. Congrats, 10.4 Griffin Door. Is that how you write Griffin Door? Yes. Right click and run 665. Enter ten points, four griffin door. Only problem in here is if I type in, for example, 12 and hit Enter, I still get congrats, which is not good. Now, the next people, or some of you might have done the following, They said Lip, the guess is equal to the actual H. Then added a tab in here in order to create an indentation, it's part of the block of code. Right click and run 6665. Hit Enter, Congrats, run ten points. Four griffin door. Excellent. If I type in 12, I don't get the answer. Nice. Excellent work. That is correct. That could work, but there is an even better way, because remember, when we're working with an L, if we actually evaluate the line of code, this is an extra evaluation that we don't really need because, and I will click at the end of the line and hit control forward slash to comment it out. We can simply use an LS. If I write, click and I run 665, boom, Congrats run again. 1,000 guess lower. Why does this work? Well, because if the guess is not less than the actual age and the guess is not greater than the actual age, then what is the guess? There's only one possibility, and that is that it's equal to the actual age. There we go. I hope you understood. I hope this all makes sense. What I want you to do now is I want you to run this through the debugger. Take your time. Use the debugger. Go through the code, try all the possibilities. I will do it with you in 321. Add a break point right here. Right click debug. Close this down. What is Flamels age 12. Hit Enter. All right, guess is 12, Is it less than the actual age? Yes it is. Please guess higher. Let's strike the scan debug 1,000 Hit Enter, is it less? No it's not. Is it greater? Yes it is. Please run on Guess higher, guess lower. We print out. Now if I right click and I debug again, you can simply click on the debug, right here at the top. 665 hit is less than the actual age, is greater than the actual age. No it's not. Then we simply jump into the print. We finish up with that. Now let me take this line back and comment the L's line. Right click debug. So what is L H 665. Hit Enter. Notice what will happen. Is it less than the actual age? No, it's not. Is it greater than the actual age? No, it's not. Then we have to evaluate this again. Is it equal to the actual H? Yes, it is. And then we print out, so you can see by using an L, unnecessary LF, you can see that we just add one extra evaluation, which is not something that is recommended, even though this is not a huge problem. At this 0.1 extra evaluation, you're telling me like who cares? Like this is a few milliseconds of extra work. But imagine if we had a loop that does this 1,000 times per second. Just imagine it in this situation. Of course it's not possible, but code optimization is something that you have to be conscious of even at this point. Using an L in here does the same job as the lift without any further or future consequences. Which means that it's better to use the Ls just to remove one extra operation like these operations. These comparisons take a few milliseconds out of your code, And it's better to save on these milliseconds at any point possible. Thanks so much for watching. I hope you enjoyed, and the next video is all about giving people second chances. So I'm going to see you in that video. Bye bye for now. 26. 6. Giving a Second Chance: Welcome back my favorite python programmers brand new video. And this is the season of giving back. Of course, it depends on where you are or when you're watching this without any further ado. And we'll stop the jokes. Let's go ahead and get started. We want to give a second chance because he's a good fellow wizard. What do we do in here? How do we give a second chance? Well, this should be fairly obvious. We need to get another input in here. I will get guess equal to integer input and this indicator right here. And then we of course need to check if the guess was equal to the actual age we're going to print out. Well done Mr. Wesley ten points or at this point I think we should give him like five points because it took him to try. So five points for grid, right click, run. Let's say 5,500 Boom. Please guess higher. Oh nice. Now I get a second input. So I type in 665. Boom. Well done, Mr. Wesley. Five points. Four Griffin Door. Now, again, keep in mind we're using two equal signs, which means that we are comparing the two values to check if they are equal. When we're using a single equal sign, it means that we are assigning a value to a variable. Now the only problem in here is that if I right click and I run, I type in 900 and hit Enter. I only get told to get slower without any way for us to properly get a second input. So what do we do in here? You should know by now we should do the same thing for the lower. Now, if I write click and I run, I want you to also realize that. Let me add in here Mr. Ron. Just so we can distinguish between this print and this print. If I write click and I run and type in 900 and hit Enter, please get slower and type in 665 Enter. There we go. Well done, Mr. Round five points for Griffin door. This is the line of code, this is the print that's executing and not this one. Why? Because we have 900, which means that this condition is not true. That means that we go into this Lyp check if this condition is true and because it's 900, it's greater than the actual age. We go into the block of code and we get another input and we check that the gas is equal to the actual age. This is actually called a nested if, meaning that this is an if inside of another if even though it's Santa Live. But it's the same concept in here. We then print out the following. Now the only problem, and one more thing, notice the indentation. Now we have a double indentation. I told you a few videos ago that we cannot have extra indentations only in this case where we have a block of statement inside of another block of statement, Can we have these double indentations in here? The only problem in here is that if I write click Run, and I type in 900 and then I type in lower, okay, 800, I don't get anything printed out to me. At least they should tell me that I'm not good at this. I'm dumb. I should study more for the following tests to know what Flamel he is. At least some indication in here should happen. That is going to be your challenge, to add an L statement to our new if statements. And make sure you have the right indentations for these. Pause the video right now and go add an L to our new ifs. Welcome back. How did you get on with that? In here, it's very simple. Simply add an L to these if I'm going to print out wrong again, wrong again. And then in here I will add an L and say you got it wrong again. When I write click and I run, let's type in 900, 800, you got it wrong. Again, this line of code was executed. Let's run this 400, 500 win. This one is different. This is the line of code that was executed. Thank you so much for watching. I hope you enjoyed. In the next video, we're going to be looking at testing operators. So we've seen some of these operators already like the less than, the greater than, the equal to, the greater than or equal to, the less than or equal to, the less than or equal to. But it works the same way as the greater than and equal to. In the next video, we're going to see another operator which is the different than. It comes in very handy. I will see you in the next video. Thank you so much for watching. Just as an extra challenge, as an extra homework, even though I don't have it right here. Try to use the debugger in various places in here to make sure that you understand how everything is working. The only downside of using a debugger when you have an input is that sometimes it can go haywire. Like for example in here if I step into yeah, and the console now it's waiting for the input. If I type in 20, hit Enter, you can see that now it doesn't step into correctly, like some weird things happen. Let me try this again, like 120, Hit Enter. Okay, there we go. Now it works. You have to use the step into my code as you can see, because it can get hung up on going through the code inside the input. This is something very advanced, don't worry about it. When using the inputs, use the step into, for example, in here you get this, okay? Step into my code. All right, and then type in 300, it, I mean, step into again. All right, there we go. This is how it could work. All right, ladies and gentlemen, thank you so much for watching and I will see you in the next video. 27. 7. Testing Operators: Welcome back my favorite Python programmers to a brand new video. In this one, we're going to be looking at different testing operators. As I told you in the previous video, you've already seen a lot of these operators and these are the operators we have the less than, the less than or equal to, the greater than, the greater than or equal to, the equal to. Finally, the one that we have not seen before, which is the n equal, which is an exclamation mark followed by an equal. Very important to remember. Very important when using. Let's not waste any more time and let's look at the use of these operators. If we go back into our game that we've created in here, I want to write or have the same output. Let me rephrase that. I want to rewrite the code having the same output using different operators. First of all, I'm going to select all of this and I'm going to hit control control forward in order to comment all of it out. Then I'm going to say if the guess is different than the actual he, I'm going to say if the guess is less than the actual he, I'm going to print out please run guess higher and then else print. Please run guess lower in here. I'm going to say else print. Well done Mr. Ron or Mr. Wesley. Ten points, four griffin door. Okay. So, how does this work? I want you to pause for a second, and I want you to think of how this actually works. First of all, we check if the guess is different than the actual age. If it's not, meaning this condition is false, we go into the else Correct, and we print out Well done, Mr. Wesley. Ten points for Griffin door. Let's test it out. Right click, and run 665. Hit Enter. Well done, Mr. Weasley. Ten points for Griffin Door. Now, if it's different than the actual age only then we go and check. If the guess was less than the actual age, we tell the user to please guess higher. If it's L, then we tell the person to guess slower. Now, why did we not say lip guess is less than or greater than the actual age in order to guess lower? Think about for a second why we didn't use the lip just like we did in this case right here. I mean, in here we checked if the lip is Lip greater than actual he. Well, it's for the same reason that we didn't use an lip right here, and instead we chose to use an L. Because in this situation, we don't want to evaluate this unnecessarily. And why is it unnecessary in here to check if it's greater? Well, because we've already established that the age or that the gas is different than the actual age, It means it's either going to be greater or it's going to be less than the actual age. After we made sure that it's not equal to the actual age, we checked if it's less than the actual age because it is less than the actual age, or if it's not less than the actual age, it means that it has to be greater than the actual age. There's no other way around it. It cannot be equal. If it's less than, it means it's greater than, that's why we only need the Ls in here for this to work. Of course in here we're using the different than expression. Yeah, the only problem in here is that we don't get a second chance. So if I type in 100 or 900, please run guess slower but I don't have another input. And that's where your challenge comes in. Your challenge is going to be to get a second input, get a second input from the user. Check if the guest was correct and if it's not, print out a message based on the result. Should I give you a hint? Maybe I shouldn't. You should only have one more input. Try to think of it. Only one more input in here. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? By the way, if you love the scores, if you're enjoying my teaching, if you are learning something, please leave me review. It helped me out a lot. But anyways, what should we be doing in here? Some of you might have done the following. After we print out, we get the guess equal to input. And then in here, let me just add this extra prompt and then we will what. Sorry. There we go. And then we will check if guess equal to the actual age, print out well done, five points, L print out wrong again. Then what you did is you copy this and put it in the Ls that it would actually work. Because now if I write Click I run and I type in 500, 665. Well done, Five points, excellent work. The only problem in here is that this is called redundant code. Whenever you find yourself copying and pasting code, you should immediately start thinking, what am I doing? Alarm bells should start triggering in your head that there is a better and easier way of doing this. You should never have to copy code. Of course there are exceptions, but most situations in 95% of the time where you're copying code, you can avoid it. How do we avoid it in this case? Well, if I tell you that we don't actually need to get a guess in here, we don't need to get a guess in this L statement shift to take this back. We only need to get one guess. So if I write click and I run 90665, well done, Write click and run 30665. Well done. What did I do in here? Well, instead of putting this second guess with its check for the actual age inside of this block of code where we check if it's less than the actual age. Or in this block of code where we check if it's greater, it doesn't matter. We can simply put it on the outside. Notice this is not part of the else, this is not part of. It's for a second if we didn't give suggestions, if we had the following code. So as soon as you get the guess incorrectly, you want to get a second guess. It doesn't matter if it was higher, doesn't matter if it was lower. As long as it's different than the actual age, we will have to get a second guess. And that's the whole point. These two if statements in here are just a guiding point for the user, if they should be guessing higher or they should be guessing lower. But other than that, we will have to get a guess. Either way, it doesn't matter if we should guess higher, it doesn't matter if we should guess lower, we should get a guess. That's the whole point. I hope you understood how this works. Some people really get confused, but you should take the time to properly understand and learn why we have this guess here. And not inside of the L, not inside of the F. Only a single one works enough. Okay, thank you so much for watching. I hope you enjoy it. And in the next video we're going to look at writing ifs in a slightly different way. So bye bye for now. 28. 8. If In A Different Way: Welcome back my favorite python programmers to a brand new video. And in this one we're going to look at ifs in a different way. So what we'll be doing is we're going to be rewriting our program to guess the correct answer first, and then we are going to proceed and do everything else. And when we say we're going to be rewriting the code, I mean you're going to be rewriting the code and the best types of videos the best kinds of videos are the ones that you start off with a challenge, right? No. Okay. Please don't click off rewrite the code to check if the user's guess was correct at first, write the code if the guess equals to the actual age, and then continue from there and make the necessary adjustments to have the same output. Again, we want the same output. What I want you to do, in fact, is I want you to not comment this out. Instead, I want you to add a print in here. Of course, I want it outside everything, and I want you to add a multiplied by 50 and then proceed to write the code to have the same output. But this time you'll need to start with the gas being equal to the actual H. And I have a hint for you, If you don't want the hint, pause the video and go to the challenge. If you do want the hint, 31, you don't need to delete or add any code. Simply move some code around. Pause the video right now and go to the challenge. Oh, okay, welcome back. How did you get on with that? First things first is we need to start writing the initial conditions, which checks if the guess was equal to the actual age. If it's equal, then what I want to do is I want to simply say, great ten points for griffin, right? Then I'll have an L. What should we do in the L? Exactly the same thing that we did in this case. This is a simple moving around of the code. We don't need to add anything. We don't need to change anything because we changed the initial condition. All that we need to do is change the position of our code. Now if I write click, but you know the problem with this is that we are going to get other inputs in here. I mean, you know what, Let's do it. So 300 hit enter, please guess higher, 665 hit enter, and there we go. Well done 5.4 griffin door, but in here, because the guess changed. Why? Because the guess in here was another input and it was 665. Doesn't really work, so we should in fact comment this out. Right click and run 300. Please guess higher 665. There we go. Well done, five points. Okay, so it's the same output, it's the same exact code. We get the same results, we only changed the operator at the top. So this is just a good exercise in showing you that sometimes you can have the same outcome using different codes. Sometimes it doesn't matter which type of code you use, sometimes it doesn't matter what type of code you use or what condition you write. As we saw in this video in the F statement where we started with g being greater than 17. And we've seen that it's not as good as using age less than 17 in this case. Sometimes it's better. So thanks so much for watching. I hope you enjoy it. And I will see you in the next video where we are going to be talking about complex expressions. Meaning what if we have multiple conditions in here on the same line of code, not on an LF, on the same line of code. I will see you in the next video by bye for now. 29. 9. Complex Expressions using and, or: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at complex conditions using, and so far we've only done very simple conditions. What if, for example, we wanted more than one value evaluated, For example, age greater than 17. Maybe if we want to check age being also less than something, that's where we start using complex expressions using and we're going to also be looking at and and or truth tables. Let's first of all create a new Python file in here. So new Python file and I'm going to call it plex expressions in here. First of all, we're going to get the input for a temperature. What we want to do is we have a gaming PC where we want to play some games, but we can only play those games if our GPU is at a certain temperature. We're going to first of all take the temperature, The temperature, that's how you right temperature. Yes, Integer input. How hot is your GPU? Gpu stands for Graphical Graphical Processing Unit, I think. Yes, I think so. That's the GPU. And then we're going to check if the temperature is greater than or equal to 20 and the temperature is less than or equal to 70, then we're going to say, great, continue playing your game at 60. Continue to playing your gum. Eat nice 60 FPS. L print out, oops, sorry, you can't play your game body. We forget that we are using single quotation marks. It's okay. As you can see, first of all, we have a small squiggly line telling us that we can simplify chain comparison. This will be handled in the next video, but for now what we need to understand is that in here we're checking if the temperature is greater than 20 or greater than and equal to 20 and the temperature is less than 70, then we can play our game. Let's see how that looks in the real world. When we run, how hot is your PC? 20 Hit Enter. Great, you can continue playing your game. Why? Because 20 is greater than or equal to 20. Keep in mind the equal to is the keyword. Let's run again. 17 hit Enter. Oops, sorry. You can play your game. Now, some of you might be saying, wait, wait, wait, wait, wait. Michael, Michael, 17. It's not greater than 20, I mean. Okay, I'll give you that. But it's less than 70. So what gives, what's the matter? Well, when we are working with an end, we have to have both conditions true. So this should be true and this should be true. Both of these conditions should be true in order to evaluate the entire condition to true, in order to go into the block of code. For example, if I write, Click, and I run and type in 100, 100 is greater than or equal to 20. The first condition is true, great. But the 100 is not greater than 70. It's greater than 70, It's not less than or equal to 70. What are we going to get in here? Oops, sorry. You can play your game body. We need both conditions to be true, in order to evaluate to true, in order to actually go into the block of code in here. So with that out of the way, let me tell you a little bit about the truth tables. So if we have a true and true, we get a true. If we have a true and a false, we get a false. If we have a false and true, we get a false. And if we have two false, we get a false. Again, before we move on, like you have to understand that we can add more than just two conditions in here. We can add no matter how many ones we want. If all of them are true, then we get true and we can go in. If only one of them is false, then we cannot go in. It's similar to when it's like the veto, you know, the five most important countries, or biggest countries, or powerful countries whatever, they get a veto vote. So for example, let's say a US and Russia, and I don't know, France and Great Britain all say yes to, I don't know, fighting aliens. If then China decides that they don't want to fight aliens and they veto the decision, then we don't fight the aliens. It's the same thing in here. If everybody, if all the conditions, the temperature is greater than 20 and the temperature is less than 70. And something else. And something else. And something else. And then one condition is not true, this entire statement would be false. And we would not go into this block of code that's the end truth table. Now we also have the Or Truth table. We haven't seen the Or. We'll see it in the next video. It will be a challenge for you. The truth table, we have true or we get true. If we have or false, we get true. If we have false or true, we get true. And if we have false or false, we get false. The truth table is different than the end truth table, where we have to have everything being false. If only one condition is true, then everything else will be true. Okay? So that is everything that you need to know about complex expressions with the ends and the ors. Obviously, there's a lot more intricacies to this. You will, it's not very common that you'll find the ends and the ores, but it's very important that you know them. They will come in handy in many situations. They are a bit more specific when it comes to their use. It's not very widely used. You can get around using the ends and the ores most of the time, but you might, and you will, you probably will come across the ends and the ores, so it's a good idea to know how they operate. And the next video we're going to be handling this squiggly line in here that's telling us simplify chain comparison. We can actually write this in a more simple way. So I will see you in the next video. Bye bye for now. Oh, and please. By the way, if you're enjoying this, leave me a review. It helped me out a lot more than you can ever imagine. If you ever have any questions, please hit me up. I have my number somewhere around. You can always contact me. You can contact your dedicated instructor. And I will see you in the next video. Bye bye. 30. 10. Simplified Chained Comparison: Welcome back my fellow Python programmers. In this video we're going to be simplifying chain comparison and we're going to have a very confusing challenge. So very exciting times. First of all, let's look at the expression that we've written in here. Intelligent is trying to tell us that there's a simpler way of writing this instruction for expression. If we write Click and we click on Show Context action, you can see that we have many suggestions in here. But one of the more important ones, these are just for rewriting. But you have this light bulb. Usually the light bulb is a good idea. You can simplify the chain comparison. If we click on it, you'll see that it changes our expression to the following. This is written in a different way, but it should probably be more familiar to you. Where you can see that the temperature should be greater than or equal to 20 and less than or equal to 70, it should have the same result. So whenever you change your code, always make sure to test everything. And also always make sure to test the extremities. What I mean by that, when I run, for example, 50 should work, right? But always test out 2070 numbers such as 71.19 Always test the extremities. Always try to know what would happen in the extreme cases with that out of the way. Let's now take you through the challenge. So what I want you to do is I want you to use or I want you to change the condition to use or instead of, and of course, make sure to make the necessary adjustments to the code. And of course, this should be obvious. We want to have the same output, we want to keep the same knowledge in here. For example, we'll add a print with I don't know, the dash is, again, multiplied by 50. I want you to write the code in here where we use an Or and we still have the same expression for the temperature. Meaning for example, if I type in 50, I should get yes, you can play your game, if I type in 100, no, you cannot play your games, et cetera. But this time using an Or. Posit the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here, I'm going to type in the following. If the temperature is less than 20 or the temperature is greater than 70, then I will print out, you cannot play your game. I think this makes a lot of sense. If the temperature is less than 20 or the temperature is greater than 70, you cannot play your game body. And then in the L will print out, great, you can continue playing. I think this makes sense. I don't think it needs too much explanation in here. If I write click and run, you cannot play your game 20. Great. You can play your game 1971. You cannot. And there we go. Everything looks to be working correctly. All right? Nothing too much in here. Simply checking if the temperature is less than 20 or the temperature is greater than 70. Now notice the logic that's happening in here. 66 is not less than 20. That's correct. Because 66 is greater than 20. So this condition is false, right? But 66 if temperature and if temperature is greater than 70, okay? So this is false and this one is false. So we have two falls, and because this one is false and this one is false, great, you can continue on playing. So this entire expression evaluates to a false. In here, let me show you, take you back to the or truth table. We need to have both of them false in order to get a false. But for example in here if I write click and I run and I say like 12, okay? So 12 is less than 20. All right. So this condition is true, but it's not greater than 70. So this condition is false. But because we have a true and a false, or true or a false, we get a true. So this entire expression evaluates to a true. It means we go, oops, sorry, you cannot play your game. So before we move on, something very important to keep in mind about how Python evaluates this. Python stops checking the rest of the ends when it finds one of them to be false. Because as I told you, if we have 100 and conditions and 99% 99 of them are true and one is false, then the entire expression is false. What Python does is it continues to check conditions if they are true. When it finds one false, it does not continue looking through the other ones. The opposite is true when working with an or. It will look through all the expressions in the re until it finds one to be true and it evaluates everything to be true after it. So I hope you enjoy it. I hope that made sense, and I hope you understood how we're using the R. This is a bit of a confusing challenge. For some reason a lot of students find it very, very hard to wrap their heads around this. Take the time, try to rewrite it yourself, try to understand everything that's happening. And in the next video, we're going to be looking at the truth value testing. Which is going to be a very important and very fun video. So I will see you and the next one by wife for now. 31. 11. Truth Value Testing: Welcome back my favorite python programmers. In this video, we're going to be looking at truth value testing. And what do we mean by that? We mean by that where sometimes conditions don't look like normal conditions, like when we're comparing two things, but they still evaluate to a true or a false. For example, a zero always evaluates to a false. Interesting. Right, let me show you the following link and it will be linked somewhere. Of course, if it's not, please contact me. I always forget these things in here. If I show you the following, as you can see, we have the built in types. You can even look through the built in types, Python, standard library documentations, the typer, and to Google, you'll find it very easy. The truth value testing any object can be tested for truth value for use in an F or a while. We're going to see the while in the next section condition or as operand Hm. Of the bullion operation below. By default, an object is considered true unless its class defines either bull method returns false exactly, et cetera, meaning that every object, if you just try to set an object, it evaluates to a true. And I will show you what I mean by that later on. But let's, let's look at a few objects that could be considered false. For example, when we're using a non or a false, we will see none in the next section or the section after that. For example, zero evaluates to a false 0.0 A float zero, j and it's an imaginary number. Decimal zero or fraction zero to one empty sequence and collection. So if you have an empty string and you try to check for it, it would evaluate to a false if you have empty parentheses, empty square brackets. So these are lists and toupples. We will see them in upcoming sections. There we go. You can also read, for example, this right here. This is where I did not create the table that you saw a few videos ago. I actually got it from here. And as you can see, they have an extra thing which we are going to use, which is is and the is not. Did we use it? I think we did use it in the previous section, but we're going to look at it more this time. As you can see, the equal, the not equal and the object identity where you try to check if an object is the same as another object not equal to is the same object. So we're going to see that later on. But for now, let's test out these theories and check if zero is actually evaluated to a false. Back in our code in here, we're going to create a new Python file that we're going to call the truth value testing. In here, I'm going to say if zero I will print out true, l print out false. Even before we run this, look at what we are getting, we get a high light over the print true. If I hover over it, it says this code is reachable. Why? Because zero will always evaluate to a false, which means this entire expression is false. Which means we will go to the Ls and print out false. If I write click and again false, this will never change. This code is reachable. Now if we change 0-1 as you can see, now this code is unreachable because one will always evaluate to a true run, true, true, true. And it's not just the one, if we type in whatever number we want or anything for that matter, it will always evaluate to a true. Anything other than zero evaluates to a true. And the same holds true for 0.0 or will it? Oh, yeah, there we go. It also evaluates to true. This is what we saw right here, 0.00 j, et cetera, et cetera. For example, if we have a false in here, of course it will evaluate to false, it click and run false. If we have none, which is something that we'll see later on, we also get a false. This is the point of value through testing it's values that are not. You might not think that zero would create a false, but it is considered as a false. Okay, so with that out of the way, let me show you a better example of this or a more practical example of this. So for example, in here I'm going to say name equals input. Give me your name, give me your name. And then in here I'm going to say if name. So I'm simply checking for name. I'm not checking if it's equal to something. I'm not checking anything. I'm just saying if name print out, hey, how are you else print, who are you? If I write, click and I run and I type in Michael, boom. Hey, how are you Michael? Perfect. If I run this and I just have a space, hey, how are you? Because space is also considered to be of value. But if I write, click and and I just hit Enter, it tells me who are you? If I don't type in anything, I just hit Enter, it tells me who are you. Why? Because we don't have anything on the name. And let me actually try to print out name at the end. If I right click on, and I just hit Enter in here, as you can see, I don't get anything. I just get an empty space. What's an empty space? Where is it? It's this right here. It's an empty string with nothing inside it evaluates to a false. Before we continue on, I have a bit of a challenge for you to check for an empty string change from a simple condition to check if the name is actually not empty. So should I give you a hint if maybe you didn't understand what we want in here? So what we're doing in here is because the name is empty and it doesn't have anything in it, we just say if name we want to change this. What does this expression mean? This is what I want you to do, to change this expression to better reflect what we're actually checking. Maybe you're still confused. If you want, you can get the hint, but it's a bit of a big hint if you don't, if you want to go search for this on your own past the video right now and go do the challenge. If not, I'm going to give it to you in 331, an empty string. You need to check if the name is not equal to an empty string. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? The only thing that we need to do in here, as we need to specify that we're checking if name is different than an empty string. This is what we are actually trying to say when we write if name, we're checking if it's not equal to an empty string. That's all that we needed to do. Let's run this. Hit Enter, who are you? Run this type and anything else? Hit Enter, there we go. All right, so I hope you understood in the next video we're going to be looking at In and not in to check for conditional statements. So I will see you in the next video. Bye bye for now. 32. 12. Using in and not in in Conditional Statements: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be using and not in conditional statements. I should really look into changing the name of these videos in the lessons. Anyways, there are two uses, one for the loops and one for the conditions. But this time we're going to be simply learning about their use in our simple small conditions. Let's go ahead and create a new Python filing here. We're going to call the car, underscore checking both in here. We're going to have a car which is the BMW M three, nice, So this is our car. And then we're going to have an input, which is going to be the car name equal to input. And what car would you like? What would you like? And then I'm going to check if the car name is in the car. I will print out. I will print out the replacement field car name is in the replacement field car. Else I will print out, sorry, we don't have a replacement field again, I forgot to. I just got in the habit of using single quotation marks before. I used to always use double quotation marks. Now I always use single quotation marks. And because I'm using single quotation mark, I get these errors all the time. I don't know. Force of habit, I just forget, you know, but it's okay. No harm, no foul. If I write click and I run, I type in, what car would you like? Well, I would like a BMW. Bmw is good. Bmw is in BMW, three. So everything turns out to be good. But if I write Click and I run and I type in Ferrari. Sorry, we don't have Ferrari. Hmm, not very good. Well, because it's not part of the BMWM three. There is no sequence of characters in here that is in BMW. So for example, if I write Click and I run and I type in B. Okay? B is in BMW. If I try this again and I type in M3m3, is in BMW. But if I type in M space three and I hit enter, you can see, sorry, we don't have a M space three. So it should be the exact same as we have it in here. The same sequence of characters that we have in the car is used to check. If we have this later on, we'll be using this for list as well and in loops, but for now, using it for conditional statements is enough. Thank you for watching. Before we leave, you have a challenge to get another input. So you need to create another condition for the if statement. Check if a string is part of the car name available and instead of the in using the in. So you need to use a string directly instead of having this right here. So instead of car name, you need to have a actual string being used to check if it's in the car name. Okay, positive video right now. And the more important part is just to use the K in this challenge positive video right now and go do the challenge. Okay, welcome back. How did you get on with that? I will comment this out and what I'm going to do is I'm going to check if BMW or excuse me, not in the car name will print out. I will print out, sorry, we don't have a BMW BMW in the car name else. I'm going to print out. Actually, I have it. I'm going to print out. Wait, not in that means Ok. Now, it's all good. We are going to print out, we're going to say BMW is in the car name. Right click and run. If I type in Ferrari. Sorry, we don't have BMW in Ferrari. Makes sense then BMW. Bmw is in BMW. Everything is working in the can't be both. There's a problem in here. If I write Click and I run, I type in BMW upper case, BMW upper case. It happens sometimes hit enter, sorry, we don't have BMW and BMW. The problem in here is that characters that are in the upper case are considered to be different than characters in lower case. So for example, if I write BMW just one character in the upper case and hit enter, sorry, we don't have BMW and B M. What's the solution for this? It's very simple. There's something called a case fold in here, I can add case fold. If I hover over, it returns a version of the string suitable for caseless comparison. Basically what it means is it takes everything to the lower case. When I write Click and I run F and B, hit Enter. Bmw is in BMW because we use the case fold of the car name. Take it down to the lower case and then compare it with BMW and everything works perfectly. So thanks so much for watching. I hope you enjoyed. This is the last video of section three, I believe. Maybe I'll add more later on when we update the course. This master class will always be updated from time to time. So maybe I'll add more projects, maybe I'll add more lessons in here. If I deem it necessary or something updates in Python, I will always be up to speed with that. Thank you so much for watching. Congratulations on making it this far. The skills that you've learned so far are indispensable. In the next section, you'll be learning a lot more about loops, about list stopples. You have a long journey ahead of you, but it's a very, very fruitful journey if you stick to it. If you're enjoying the videos, if you're having fun, if you're learning, if you like the quality of the sound. I'm doing my best in here, I hope. If you're enjoying all the quality of the sound, the editing, the everything, please let me know in a review. Wherever you're watching this or contact me, tell me. Wow, Michael, I am loving this like Mcdonald's. Thank you so much for watching and I will see you in the next video, or next section, or wherever life takes us. Bye bye for now. 33. Section 4 - Loops in Python | 1. Introduction To for loops: Welcome back my fellow Python programmers to a brand new video and a brand new section. And in this one we're going to be looking at loops in Python. A lot of people find this part of Python and programming learning in general very difficult. Where they have to understand this very new concept, which is loops. Which is just having the same code being iterated over and over every single time with a different outcome, using different values. But I want you to not worry at all. I've created the most comprehensive way of learning loops that I possibly can. Obviously, it takes a lot of concentration on your part as well. You have to take your time, understand everything that's happening. And I want you to really give me your full concentration. You'll, for your full attention because the things that we are going to learn are going to be very crucial, very important. Not very difficult, but that require immense concentration. So let's go ahead and get started. And first of all, we need to understand what are loops. Actually, loops can execute a block of code a number of times, and that's the whole basic thing of it. They just have the same block of code executed a number of times. Loops are handy if you want to run the same code over and over again, each time with a different value. So we have the same code that we've seen before, just like we had codes and the F statements that we've seen. But now we want to run them multiple times, each time having a different value. And you'll see what I mean by that. Let's look at a general structure of a four loop. So first of all we have four number of times we want to loop, and then inside we want to do some stuff and the code to execute. And of course, this is a block of code, which means that it is indented. You can see the indentation right here, four number of times we want to loop. And then the stuff that we want to do right here. Without any further ado, let's move on to some examples and start looking at how four loops work. First of all, let's go into intelligent in here. We're going to create a new project. It's of course going to be a Python project. I'm going to put it inside of the Python course. Inside of code right here. Yes, code and then backslash. And of course, you can save it wherever you want. And I'm going to call this loops in Python. Hit Finish. Yes. All right, there we go. So now we have loops and Python. First of all, we're going to create a new Python file which is going to be the four loops. And with an underscore in between, we don't have to do the underscore, but it's usually better to have our file names all as a single word and without capitalization, because capitalization will be kept for classes later on that's in the future. Don't worry about it now. For now, let's just create this file which is four loops and I think intel J. I will use the magic of editing to see you when we freeze. Okay, welcome back. So first of all, I'm going to create a very simple message. And I'm going to say that the message is equal to the following string. I'm learning Python as we've seen before. Each character is an item of itself, meaning that each one of these characters has an index attached to it. So what I'm going to do is I'm going to go over every single one of these characters. Meaning that I'm going to say the following. Follow with me. Four character in message, Colin, Print out the character. First of all, I want you to think of what the output could possibly be in here. If I right click and I run, this is the output that I get. Let me just stock it right here. Look at that. I'm going over every single one of the characters. And that also includes the space. We've seen this before. This includes the space. So I'm going over every single character. I'm picking it out of the message, I'm putting it in the variable character, and then I'm printing out character. Then I'm going back, I'm going to the next character, which is the apostrophe. I'm putting it in the variable and I'm printing out character. I'm going back, I'm increasing by one. I'm going to, I'm picking out the character, putting it in the variable character and printing it out the space, the L, E, A, et cetera, et cetera. By the way, we don't have to name this character. We could name this x if we want. The output is going to be the same. This is just the variable name, but I'm going to keep it as character because it represents what we are doing in here. I'm sure that at this point you're still not entirely sure of how this is working. Don't worry. Look at it carefully and understand, first of all, at least what is happening. You don't need to go too deep in here. You don't need to fully comprehend the minute small aspects that are happening. Just know that we are going through the message and putting each and every character into character and printing it out at every iteration. Now at this point, once you've looked at this breath, breathe out. I want you to do the following challenge. And don't worry, the challenge is not very complicated. It's just you using the debugger, something that we've done already. I want you to set up the breaking point on the fore loop. And I want you to go through your code and make sure you understand how this fore loop iterates over the string message. Pass the video right now and go do the challenge. Okay, welcome back. Maybe you've done the challenge yourself, maybe you're waiting for me. That's okay. Let's add a breakpoint in here. Right click and bug our for loop. There we go. You can see that our message is the following. Of course, it's using the backlash for the special character which is a single quotation mark. But now we are going to step in and you'll see that the character is. If we step into again, we go back to the top and you'll see that on the console we print out. Keep in mind this is what's being printed out right now when I step into again now even though it says the back single quotation mark, but it's just the quotation mark. I continue. The character now is M. I print out M. Now the character is an empty space. I also print out the empty space. This is not nothing, this is an empty space. Now the character is L. I printed out the character is I printed out. For some reason, this is not refreshing. Let me check the message. I'm learning Python. But in any case, as you can see, we are changing the character and clear all. Let's look at what happens. Okay, there we go. Now it's working again for some reason. But as you can see, we are going over every single character. Let me terminate this and try to debug it again on your side. I'm pretty sure you're not having this issue. If you are, there we go. We're printing out the apostrophe. The, the space. Okay, there we go. Now it's working again. I'm not sure what was happening. L, E, and again it's stopped. But as you can see, we are going through every and each character. This was your introduction into loops. Of course, there is a lot more to loops, but what I want you to understand is we are doing this code multiple times. Let's look back at the structure. So first of all, the loop can execute a block of code a number of times. This is our block of code. Notice the intentation that's behind it. Loops are handy if you want to run the same code over and over each time with a different value. We're running the print over and over and over every single time with a different value where the character is changing the value. The structure of a four loop is just four and then the number of times we want to loop right here, we start with the four and then we have the number of times that we want to look. Now we didn't define or we didn't set the number of times that we want to loop beforehand. We just said we want to loop over this message because message is a string and strings are meaning that we can iterate over it. So we're going through each individual character, extracting the information from that string and putting it into the character variable in here. And then printing out the character. Then we're changing the value and printing it out again, again and again. And we can keep doing that until we get to the end. So ladies and gentlemen, thank you so much for watching. In the next video, we're going to be looking at debucking loops a little bit further. So I'm very excited to see you there. Please don't be petrified by what you, what you just saw. Take your time. Breathe and breathe out and trust the process. It's not as hard as you think it is. So I will see you in the next video. Bye bye for now. 34. 2. Debugging a for loop: Welcome back my favorite python developers to a brand new video. And in this one we're going to be debugging our for loops further. First of all, we need to look back at an older project that we had. I'm going to create a new Python file in here. I'm going to call it data data separation. Let's just call it dat coming in loops. I'm not the best at naming things, okay, so let's just get that out of the way. If you remember, in an older project, we had the following data coming in. Now mine might be different than the one that you wrote, but the more important part here was that we had the first a numeric number in here and then a character, and then four numbers, and then some kind of character and then four numbers and some kind of character. And what our goal was, it was to remove all the separators and put them on the side. Or at least to print out all the necessary numbers without these special characters being added. So the way we did that was using the following code. We printed out the data coming in from one to the end with a step of five. So for example, if I write click Run, this is the output that I get. I get all of these separators. And now I can use that as a filter to remove all the unnecessary information and have clean numbers coming in. Well, the problem with that is if I tried to add just a single number in here, let's say for example, three, now the distance is no longer five. What I get is the following. This filter is bad. If I tried to use this filter, I would lose the two, the fours and the six and completely corrupting the data that is coming in. How would we handle this? How would we make sure that the data coming in is filtered correctly? How do we properly extract the separators to create that filter? Well, for that we're going to be using loops. Let's get rid of this code. Well actually let's comment it out just so we can always know what happened in the past. Will build on top of it in here. First of all, I will add random numbers and some random, let's just add, I don't know, a multiplication, a percentage in here, and just throw things all over the place just so we can see how we can fix these. Of course, using the data coming in and the slicing that we've done right here, it's not possible to extract this information because we have a very defined step. The way to do this is first of all to create a variable separators, sepa raters, and it's just going to be equal to an empty string. We're just setting things up. Then we're going to go through the data coming in. You should know by now how to do this. I want you to take just a few seconds to think about how we loop over each individual character and the data coming in. We say four character, remember this is just the variable name. We can call it whatever we want in data coming in. Then in here I'm going to say, if not character is numeric, I'm going to say separators plus equals the character and I will print out the separators. What is happening in here? First of all, I'm looping over the data coming in, or actually it's called iterating over the data coming in. Every single character is being put into the character right here. Then I'm checking if this character is not numeric, meaning it's not a number. If I hover over the numeric, you'll see it returns if the string is a numeric string and falls. If otherwise, if it's six, then it is numeric, this is true. True is false, which means that we don't go into these conditions, or into this condition, or into this block of code in the if statement. I hope you know your conditions well. We've extensively looked at them in the previous section. If the character is not numeric, so like let's say the dollar sign, then this statement in here is false, which means with a knot behind it, it becomes. Which means that we do go in here, and which means we append our separator with the character, and our separators string grows by the way, plus equals. I'm not sure if we went on this before, but I will just do it a second time. Separators equal to separators plus character we are building on top of our separator. So let's now run this and we are going to dissect it further. I will right click and I will run, and this is the output that I get. As you can see, I have all of these separators, including the space right here, all printed out properly. So take your time. I want you to look at this. I want you to pause the video and understand what just happened. Because I'm going to add a line of code in here that will help us understand this better. I'm going to print out the separators at every single iteration so that you can see what is happening. If I right click and I run, look at how this works. We start at the beginning, we have our six right here we are. Going through the character. We start with the six, we print out the separators. There we go. We don't have anything. We check, if not is numeric, so is the six numeric, is it? Of course it is. This is true. Not true is false. Which means that we don't go in here, which means we just go back to the top. We don't append our separator, we print out the separators. Again, this is the line of code we are printing out the separator. Now we have the the character that is numeric. Is it a numeric number? I can hear you in the back. No, it's not. Which means that this is false. Which means that this is true. Which means we go into the statement and we append our separator with the character. So our separator grows with the comma. So that when we go back and now character is at three, We print out the separators which is just a comma. And then we check if three is numeric. Yes it is. Then we don't go into the condition. We go back to the top. We print out the separators. We print out the separators. We print out the separators. And now we get to the dollar. Is the dollar numeric? No, it's not. So this entire statement is true. Which means we append our separator with the character and now we have the commodellar sign. Commodellar sign. Commodellar sign. Remember we're going over all of these. Then we arrive at the semicolon, boom. We append the semicolon, we arrive at the star, we append the star, we arrive at the forward and et cetera, et cetera. And we keep growing this. So if you can get through this properly, then you are golden. Now I have an unofficial challenge, which is to add a breakpoint in here and go through this code again using breakpoint. And I want you to fully comprehend this without any doubts. Okay, so I'm going to go through this with you. So I'm going to be debugging the data coming in. So let's go ahead and see what is happening. I will close this down. We step into data coming in is the character six. We print out the separators. Of course, the separators is just nothing. It's just an empty line. Is the six a numeric? Yes, it is. Which means not character is numeric is false. Which means if false, we will not go into this. Then we go back to the top, Now we have a, we print out the separators. If not, numeric is the common numeric. No, it's not. Which means not character is numeric is true, which means that we delve into the separators. The separators, look at what's going to happen to the separator here. Boom. Now it has a, we go back to the top, now we're working with three. We print out the separators and we have the coma at last. The three numeric. Yes it is. We do not go into the separators plus equal character. We go back in here, boom, boom, six for the dollar sign, we print out the separators. Is the dollar sign numeric? No, it's not, meaning not. Character is numeric means that this one is true, which means we do go into the statement, which means we do append our separators with the character and we add the dollar sign in here. I'm going to stop the program. I want you to continue through all of this and make sure that you understand how it's working. That is your challenge. Before leaving, I just want to show you what would happen if I just add an equal sign in here and not a plus equals. Because some of you might be thinking, what does it mean to append using the plus equals? If I write Click and I run, this is the output that I get. I simply get the last character that is not numeric, the plus. My goal in here is to add all of these together. I want to have a collection of these separators so that I can then use them at the end. That's why I add to the separator. I take the separator, let's say the separator in here is the coma. I take the separator right here. It's the coma. I add to it the dollar sine. Now I have coma. Dollar sign. And then I put all of this into the separator again. Now the separator is equal to the dollar sine. Then I find the semicolon. Now remember the separator right here is a coma dollar sign. I add to it the semicolon and, and I put this entire thing back into the separators. So now I have a comma dollar sign and the semicolon. Okay, so I hope that is clear. Thank you so much for watching. In the next video, we're going to be looking at loops over a range which is slightly different than iterating over a string. So I'm going to see you in the next video. By bye for now. 35. 3. for loops over a Range: Welcome back my favorite python programmers. In this video, we're going to be looking at loops over a range. I'm going to create a new python file in here that I'm going to call four loops. Underscore range. In here, I'm going to simply say for I in range, that range is going to be one through 30. I will simply print out in here the following to dots replacement, field dot format. And then, by the way, I don't want to use this format format. I'm not sure if I've been using it before where I changed it exactly. Because sometimes I update this course and this master class, what I will use instead is not the format, but instead inside of this, I will hit and hit Tab, and you'll see that a small F is added behind this with in here. Which gives us the same output as the format using the replacement field. But anyways, look at the output that we have. I said that I want I in the range of one through 30, but when working with ranges, just like when we were working with the slices, it's up to, but not including I starts at one, but it ends at 29. Okay? That is very important to understand. We are going up to but not including. And that's the basics of using a range. For example, I want you to add a, let's also remove one extra line. Let's add a debugger in here. Let's right click and debug our loop. Right here, we step into I equals one, I equals two, I equals three. And by the way, again, of course you should know by now that I is just an arbitrary name for our variable. You can call it whatever you want, just like we did in the previous videos where we had four character in message. The variable name should represent what we are going through. I in this case represents index, or generally in math they use I, JK, or XYZ. So you can use whatever you want of course in here. But as you can see, I increases and we print out. So we are doing a loop over this range. We are producing or printing out or executing the same code every single time with a different value which is changing. This should be very informative for you. I hope you understood what we've done in here. I hope it's clear to you. If it's not, you have a bit of a challenge, which is to test out some ranges. So I want you to play around with the ranges and I want you to experiment with various ranges and see what works and see what doesn't, just as a small hint. For example, you can use the range of -5.0 I also recommend you to go through ranges. Of course, in the next video, we're going to be delving deeper into ranges on our own, but for now, I want you to test out these ranges yourself. Pause the video right now and go to the challenge. Okay, how did you get on with that? In here, for example, let's say I want to start at zero, right click and run. There we go. We start at zero, but it's also up to, but not including. If I wanted to include the 30, I would have to go to 31 so that the 30 is included. What if I try to do minus six in here, to 31? What would happen? Do I start at minus six or minus five? I start at minus six because the beginning is included, only the end is not included. I hope you tried a few things in here. For example, maybe if I add an extra tab. Of course, this is not part of the four range or the manipulation in here, but if you try to add a tab, you'll see in here that you have a warning telling you that you've invented a few things. Still works, but you have over intented a few things. Yeah, that's the basics of it. In the next video, we're going to be delving deeper into ranges. But understanding ranges is very important because they are going to be not the main case use of our for loops, but they are still very, very important. So you need to understand how these operate. Thank you so much for watching. I hope you enjoyed this was a shorter video and the next one we're going to be delving deeper into ranges. So can't wait to see you there. Bye bye for now. 36. 4. Deeper into Ranges: Welcome back my favorite Python developers to a brand new video. In this one we're going to be looking deeper or telving, deeper into ranges. For example, what would happen if I have this range? What do you think the output is going to be like? If I write, click and I run, okay, This is the output that I get. So when I don't specify the beginning, I just start at zero. You'll see that ranges are very similar or operate in a very similar way to how slicing operates. If I don't specify the beginning, I just start at zero. We can also provide in here a step, for example, when I have three of these, I start at zero, I go to 30, and I have a step of two. What is the output? Think about it before we run. Boom, there we go. We have 0246. A boom, boom, boom. We go at a step of two. And of course, if I have three, well it should be obvious we go at a step of three next. What would happen if I do the following? If I do 36, then minus two. You should know by now that this is a step of minus two. What would happen in this case, please? I want you to think of the output before you run this. Boom. There we go. We go backwards. Of course, we have the starting 0.30 we have the end 0.6 and we have a range of minus two. I want you to take the time and play around with all of these expressions and values and see what would happen if you add a positive step with a beginning higher or lesser, or whatever. Test out a few ranges. Play around. Please make sure that you understand this correctly before moving on to the following challenge. Your challenge is to use your range. So go back and find the file, complex conditions in a previous project. And then use the range instead of the operators to evaluate the condition on the temperature. So if you remember, we created a mini mini project where we would check the temperature of our GPU and see if it was valid to play our game. I'm just going to add this code right here. So I will create a new Python file and I will call this the underscore complex range CPU temperature. And I will just paste this code in here just in case you don't have the code. If you remember, this is what we had. And then we also simplified the chain comparison. So now what I want you to do is I want you to change the operators into a range to see how ranges can also help us, not just in four loops, but also in if statements. Pass a video right now and go do the challenge. Okay, how did you get on with that? In here it's very simple. We can simply check if the temperature is in range 2071, why did we set it to 71 and not 70? Because it's up to, but not including when I write Click and I run, how hot is your GPU? If I type in 70, remember if it's between 20 or 70, if it's equal to one of these values, then we can continue playing. If I do 71, you can see that I cannot play y because 71 is not included in the range. It's up to but not including. And that is very important to understand, Ladies and gentlemen, I hope you enjoined. In the next video, we're going to be looking at nested loops, which means we're going to have loops inside of loops. So it's going to be like loop seption or loop inception. If you didn't get the joke, I'm very sorry for making it and sorry for that clap as well. I will see you in the next video where we will be creating loops inside of loops by bye for now. 37. 5. Nested for loops: Welcome back my favorite python developers to a brand new video. And in this one, as I told you, we're going to be looking at nested loops, meaning that we are going to have loops inside of other loops. So let's not waste any more time, and let's go ahead and get started. The first thing we're going to do is we're going to have the perfect example of a nested loop, which is a calendar. So I'm going to create a calendar. And why is that a perfect example? Because we have years which have months, which have weeks, which have days, which have hours, which you can start thinking up this. And it's a repeated cycle. Every year has 12 months. Every month has four weeks approximately. And then every week has seven days. Exactly. So we're going to be working on the weeks and the days in this situation. So first of all, we're going to create the weeks, so I'm going to say four week in range range. That range is going to be 15. In here. I will simply print out week to Dots, replacement, field and week if I write Click and as you can see we get week one, week two, week three, week four part of the month. But now what if I wanted to print out the days that are in that week? I would add another four loop in here that is nested inside of the previous four loop. I will say four day in range. And that range will go one through eight again. Remember why are we using 5.8 Because this is up to but not including. I will print out back. And do you remember what the backslash T does? I want you to remember very carefully. Backslash replacement field, sorry, day replacement field and the day. What does the backslash D do If I write, click and I run? Boom, there we go. It adds a tab behind our day so that we can have this nice looking separation just for the fun of it. I will also add a print in here with these dashes multiplied by 20. And add a space in your right click run and boo, there we go. We have week one, day one, day two, day three, day four, day five, day six, day seven, and then we move on to day two. So how is this working? Well, I'm not going to tell you how. I'm going to show you how I'm going to add a debugger and I recommend that you do this yourself without my help. And then re watch how I do it and explain it. So I'm going to debug our calendar and we start at the top. We start at week one. We print out week one, and now we are on the days we have day one, we print out day one, but we don't go back to the top. We don't go back to the week, we instead go back to the current for loop. We continue doing this for loop again again and again, and again until we get to seven. And then when this loop is finished, the condition in here, it is no longer true. And when I say condition, it's just the condition on the range. Meaning the range is one through seven, we are no longer at seven or we went above it, we printed out seven, we print out the dashes. And only then do we come back to the top. We increase the week, Now we're in week two, and then we go back to the day. And the cool thing about this is that we actually reset it to one and then we continue on doing this. So I hope that is clearly understood. I don't think there's much more to say in here. Again, as always, if you ever have any questions, please refer to me or your dedicated instructor. Ask them any questions. They are available to you. So I hope you understood what is happening in here. Now, I'm going to issue you a bit of a challenge. Before you do the challenge, please take the time to clearly and properly understand this because it is going to be crucial for the multiplication table. The multiplication table is another good example of using nested loops. Because we have two numbers, create a new Python file called multiplication table. Use nested loops to print out the multiplication table from one through nine. Your output should look something like this. One multiplied by one is 11, multiplied by two is 234. And then we have two multiplied by 122, by 242 by 36. And you have to do this for all the numbers. I want you to start thinking of nested loops in here, because remember, it's just like the weeks and days that we worked on. You can imagine that this is the week 1.2 on the left hand side are the weeks, and then the numbers one through nine on the right hand side are the days. And then finally, we have to multiply these together to get the output. So take your time. And of course, this should be 12 through nine, so all of the nine iterations should be there. And also, I want you to add these dashes. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? I will create a new Python file that I will call the multiplication underscore table. In here, I'm going to say four in range. And the range will be one through ten. Because remember it's up to, but not including, we want the nine to be there. Then inside I'm going to say four j in range and it's going to be one through. Then in here I will print out that I have the following replacement field. Then I hit tab for the autocomplete multiplied by replacement field j equal to the replacement field I multiplied by j. This is where most people struggle. Then finally, where should we add the print on which level? On this level? Maybe something that I did not mention in the previous example in the calendar. This print to which four loop does it belong? Does it belong to this one or to this one? Of course, it belongs to the following four loop because it is not part of the block of code of the first four loop, because everything that belongs to this four loop is indented. You'll see that this print does not have the indentation for this loop. It has the indentation for this loop. For example, I want you to tell me what would happen if I do this print right here on this level. Where will the dashes appear? There we go. We can see that they will only appear at the end because this print is no longer part of this four loop. There we go. Now it appears in the correct place. Back to the multiplication table. This print belongs to this four loop. When I write click and this is the output that I get. There we go. This is our multiplication table. One multiplied by 11 by 21 by nine, and then two by 22 by 32 by 93 by 13 by seven, et cetera, et cetera. There we go. So I hope you understood. I hope you tried your best. Many people fail at creating this challenge or doing this challenge, but if you were able to do it, it means that you are on the right track. In the next video, we're going to be continuing our use of the fore loop and we'll see another very useful case. And we'll have our first look at lists, which is going to be delved more deeply into in the next section, but we'll just have to use them in these certain specific situations. Thank you so much for watching and I will see you in the next video. Bye bye for now. 38. 6. Using continue in for loops: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be using the continuum in our for loops and understand what these are. But continuous are not enough in this video because we are also going to be looking at lists or taking a small glimpse into what lists are. So it's a collection of objects that are of the same type. Now as I told you in this video, we're just going to be covering the surface level information about lists. We have a complete section dedicated to lists and couples and data handling using these tools. But on the surface level it's a collection of objects of the same type. They can be accessed using an index, just like we can access certain characters in a string using the index. And they have methods available to them to access, sort, search, and modify. Now let's look at a structure of a list. It looks something like this. So we have a list called computer items and it's equal to, and we open up the square brackets indicating that this is a list. We will learn that there are couples that indicate or are indicated using parentheses. But for now, let's just focus on the lists which have square brackets. And you'll see that we have these objects, sometimes I refer to them as items inside of this list and you'll see that they are all of the same type. Now of course, later on when we delve deeper, deeper, we will understand that they don't have to be of the same type, but 99.999% of the time that you will encounter lists or topples or anything for that matter in your life, or the items are going to be of the same type. Just like right here, this is a list of strings with that out of the way. Let's now go ahead and test these out. Right here, I'm going to create a new Python file that I'm going to call the Car underscore dealership. I'm going to create a car underscore list that is equal to the following. I will have BMW, Honda, Ford, Volk, Volkswagen, and Volk Swagen. There we go. Sagain. Yes, finally. Then we will have Ferrari. Then we will have Ad. That will be our last car in here. We are going to iterate over this car list, just like we've iterated over the message right here. We can do the same for our list. I'm going to say four car in car list. I will print out I like driving my car. If you go back into the four, you'll see that in here we are iterating over the message using the character variable. The same thing holds true in here, we are iterating over the car list using our car variable. If I write click and I run, I get the following output. I like to drive my BMW, I like to drive my Honda, my Ford, my Volkswagen, my Ferrari I wish. And my Audi. Okay. How did I do that? Anyways, as you can see, we are iterating through the list and we are printing it out. Now the next thing I want to do is I want to issue you a bit of a challenge. Your challenge is going to be to drive all of them except change the code to drive all the cars except for the Ford. I will give you a hint. If you don't want the hint, pause the video right now and go do the challenge. If you want the hint, then you need to create an F condition inside of the for loop, and that's basically it. Pause the video right now and the challenge. Okay, how did you get on with that? As we've said, we are iterating over every single one of these objects. What I want to do is inside of the for loop, I'm going to say if the car is different than Ford, only then will I print out I like driving my car if it's different than the Ford. Now, if you use a different code and you still had the same output, congratulations. If not, I want you to start taking these challenges more seriously. Take your time. Even if it takes you 10 minutes, even if it takes you research on the Internet. If you try to do these challenges yourself, you will get a lot more benefit out of the solution that I provide you with. Now if I write Click and I run, there we go. You can see that I like driving all of these cars except for the Ford. But there is a different way of excluding an item from being printed out in a list, and that is by using the continue in here. I will change this condition to be equal to what do you think we should be writing in here? You should have a hint, which is the name or the title of this video. It's the continuum. If I write, click and I run, you'll see that I get the same output. What is the continue doing in here? Let's not theorize about what the continuum is doing, and let's actually try to use a debugger and see how this is working. First of all, we start off at the car list. There you go. Car is B, Is car equal to Ford? No, it's not. So we print out, I like driving my BMW. Honda is not equal to the Ford. Now, Ford is equal to Ford. And look at what happens. We go into the condition and now notice which line of code is going to be executed. Can you see that? Basically what the continuum does is it entirely avoids the rest of the fore loop. Everything else that's under discontinue will be ignored. Everything that's left to do in this four loop will be ignored. Some languages don't have discontinu. You're probably never going to really the continuum during your day to day life Python development. But it's important that you know that you have access to these tools. In the next video, we're going to be looking at something that is much more important, which is the break. And the break, unlike the continue here, is going to be very, very useful. I hope you enjoyed, I hope you understood, and as I told you, please start doing your best in these challenges. They are not just for skipping, they are not for you to just look at me how I solve these solutions. You have to go out and solve these problems yourself. Thank you so much for watching and I will see you in the next video. Bye bye from now. 39. 7. Using break in for loops: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be using the break in here. If we change this from continue to a break, what happens is we only print out I like driving my car until we get to the Ford. As you can see, we are not driving anything anymore. And this is most useful when you want to save memory when searching for a certain item in your list. Imagine you're trying to find the Ford. Once you find the Ford, you just print out the information or anything. You just give the value, you represent that value and you stop searching through the list, so this can be very handy. And you will be seeing a break a lot, not just during the scores, not during this master class, but throughout your entire programming career going forward. Let's now go ahead and create two more valuables in here. I'm going to say, first of all that I have the car to drive and it's equal to the Ferrari. I really, really wish. Then I'm going to have car underscore index which is equal to non, and I'm going to explain to you later on why we're doing none. But before I do that or actually there is a dedicated video to understanding why we use none in here. Before we do that, I want to just print something out that we haven't seen. That is the length of our car list. I'm not sure if we've discussed length before, I'm pretty sure we haven't. But the length, basically what it does is it gives us the length of the list or the string that we have. For example, we have 123456 cars in total. So the length of the car list is six, and that shouldn't be any surprise to you. That is the length. That's what length gives us. Now I want to do something in here. First of all, I will comment out this four loop. And then in here I'm going to say four index in range. And the range is the length of the car list. Then I'm going to check if the car list at the index is equal to the car that I want to drive. I'm going to say that the car index is equal to the index. What are we doing in here? First of all, what does this mean? If you remember, when we had, for example, right here back in the for loops, we have this message, right? I can access, for example, a message at position 12012345. Let's say five. What do I get? I get because I have 101,234.5 I have at five. The same logic holds true in the car dealership. For example, if I want to print out car list at position three, what is the output? Think about it before testing it out. The answer would be Volkswagen exactly right here. What I'm doing is I have the index and I have the range of the length of the car list, which is six. What's the range over six? It's zero through five. Index changes 0-1 to two to three. And then I use that index variable inside of the car list and I get car list at position zero. Bmw, I check if it's equal to the car to drive. If it is, then I set the car index to that index. And then when I'm done, I'm going to print out, let's just add a replacement field in here. Is in the replacement field position in here. We're going to have the car to drive in. The index or the car index. Okay. Right click and run, and your Ferrari is in the fourth position. 01234. Perfect. What I recommend you do is have a mini challenge, it's not an official challenge. I want you to add a break point, and I want you to go through this for loop. And I want you to clearly understand what is happening. And I also want you to tell me why this is not as efficient as it could be. Right click and ID buck in here. I have the for loop. I start coming in index is zero. What's at index zero? B, B is not equal to the car that we want to drive. We are at index one. What do we have at index one? We have the Honda. The Honda is not equal to the car that we want to drive. Index is two. It's four. It's not equal to Ferrari, Volkswagen, it's not equal to Ferrari. Now we are at index number four. And what do we have at index number 401234? We have the Ferrari car list at index four, is now equal to Ferrari. And is it equal to the car that we want to drive, which is Ferrari? Yes, it is. We step in here, we set the car index to the index and boo. And now we have car index equals to four. Perfect. The only problem is we've already found our car, we are ready to drive it, but we still go into the four and we still continue in here. And that is an issue because it might not seem like a huge issue to you because, well, you can just say, okay, so we did one extra iteration over the car list. What's the big problem? What's the big issue here? The issue is, what if we found Ferrari at position number four, and we had 10,000 cars, so we would have to do 9,996 more cars unnecessarily. Keep that in mind unnecessarily. And imagine if each one of these iterations required 0.1 seconds, multiplied by almost 10,000 that's 100 seconds more, I think if my math is correct. Or 1,000 seconds more, 1,000 seconds more. So imagine the pain at 1,000 seconds extra. Unnecessarily, what we do in here instead is we add a break. Now if I debug this again, by the way, I have the same output, but the only difference is when I get to index number four, I said the car index to the index, I break out and boom, look at that. I no longer go back to the for loop, I just break out and I do not continue. And if we had 10,000 cars and we found Ferrari at the fourth position, we would have broken out and we would have not had to wait for 1,000 extra seconds. So, I hope you understood how the brake works. It's a very, very, very useful tool, especially when we start working with Y loop, which is not going to be the next video, but it will be the video after that. So thanks so much for watching and I will see you in the next video where we will understand what this none is. It means nothing. But why do we use it in this context? I will see you in the next video. Bye bye for now. 40. 8. Why use None: Welcome back my favorite Python programmers to a brand new video, and in this one, we're going to be looking at why did we use none in here. So imagine that we were looking not for my Ferrari, but for my BMW. If I right click and I run, what do I get? I get zero position. Doesn't look very nice, so we can't just use the car index that we get, we need to add a plus one to it. It makes a lot more sense. And I think we can or we can not have the spaces in here. So now, it's in the first, the e doesn't look nice, but at least now we have a better position. Let's just remove this for the sake of clarity. So now, if for example, I'm looking for my Ferrari, boom, there we go. It's in the five or in the five position or in the position five. Maybe that would make more sense in the position five. Okay. There we go. Now, it makes a lot more sense. But what if I had the lambo? So I'm looking for my ambo. If I click and I run, oh, I have an error. And what does that error say? It says that it's a non type. So the car index is of type. None means nothing. It's just a placeholder. You can call it if you want, none is a constant that represents nothing, and it helps us avoid errors such as these. So now we can, for example, change a few things in here, create a condition. And that condition is going to be created by yours truly. So you're going to create a condition that checks if a car index is not none. Print out a message based on that and add an L statement with its own message printed. So, pause the video right now and go do the challenge Okay. How did you get on with that? So in here, I'm going to check if the car index is not none. I will print out your car is ready to drive. So now we avoid this issue. There we go. Now, we don't have any errors. And I'll add an L statement in here that is going to say print out. Sorry. Couldn't Blah. Cool. Find your car to drive, right click and run. Sorry, couldn't find your labo It's okay. No worries. Don't sweat, you know? My lambos probably somewhere. I don't know. Anyways, as you can see, using the noun is very important. Now, some of you might be saying, well, we could have used zero. But that's not good. Ba as you can see your lambos position number one. Not good at all. Now, some of you might have said, Why not use minus one? Well, as you can see, your ambo is in the zero position, but you're telling me that, wait, that is because we have not none in here because we're checking if it's not none, and that's why the condition is working. And that is indeed true. Now, we could have used minus one, but in certain conditions, You might encounter something like this. You might have Car list minus one. And what do we have if we try this, Car list minus one is the Audi. Because remember, in this list, we can go backwards. So it's just a more convenient way of using the n to avoid issues such as these. So I hope you understood why this is so important to use and why it's necessary to have a placeholder like. We are going to see a lot more of this being used down the line. In all of our projects, and of course, you will see it a lot in your path through Python development. Now, to be honest with you, all of this code is kind of unnecessary. There is a much better way of doing this or at least right here with this for loop. If we comment this out, we can actually do the following. We can say if car to drive is in the car list. We can say that the car index is equal to the car list dot index. Car to drive. And we're going to look more at this code, and I understand it on a much deeper level later on when we learn about lists and tuples or in the upcoming section, and boom, there we go. Now it's telling me, sorry, we can't find the lambo. But if I'm trying to drive my ford, we should see that my Ford is in position number three. Okay. So basically what this does in here. First of all, it checks if the car to drive is in my list at all, meaning that it goes through the entire list and compares each value or each item and sees or checks if we have the car that I want to drive. And if it does, then we set the car index to the car list dot index, which if you hover over it, it tells us returns the first index of value, meaning that let's say we have we're looking for Ford. We send in Ford as the car to drive to this index and it gives us the index and sets it to the car index in here. So I hope you enjoyed this is a little bit more advanced code. We're going to see it in the upcoming section. But I hope you enjoyed this video. I hope you understood why using n is so important. And in the next video, we're going to be looking at loops that are very similar to four loops, except for, it's a conditional loop. So I'm going to see you in the next video by by for now. 41. 9. Introduction To while loops: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be having an introduction into while loops. First of all, what is a wire loop in Python? Similar to four loops, It executes a block of code a certain number of times. But the difference this time that instead of determining the number of times beforehand, we wait until a certain condition is met. So that we can always redo the wire loop until that condition is met, and then we jump out of the wire loop. So let's look at a structure of a wire loop. We say that while a certain condition is true, we do some stuff, we execute some code, and we keep doing it while this condition is true. So that's the idea of it. While a certain condition is true, we execute. So we don't know the number of times this wire loop is going to execute. Unlike four loops where we have a predetermined amount of times that we will execute the code in a while loop, we don't know. We will keep doing this loop until a certain condition is met. And let's go ahead and see how that is going to look like. First of all, I'm going to go back into my code in here and I will create a new Python file that I'm going to call the Wi loops book in here. I'm going to issue you a challenge. Not where it's not a wild challenge, it's a simple four challenge. I want you to create a four loop that iterates over a certain range. I want you to print out the index at every iteration, and that's basically it. Pass the video right now and go do the challenge. Hey, welcome back in here for I in range 26, I will print out I equals I tab in order to automatically add the F behind it, which will allow us to print zero through 25. Again, we've seen this before. You should have done this challenge very easily. Now what I want to do is I want to convert this into a Wiloop so you can see how things work. First of all, whenever we are working with a y loop, we always need to have a condition or an object that we start with. Right here, you can see that we set j20. We're going to say while j is less than 26, that is the condition that we're waiting for. I'm going to print out J equal to replacement field J. Now if I write the click and I run, what do you think is going to happen? Well, as you can see, this loop keeps going. What is the problem in here? Well, the problem is that J stays zero, right? There's increasing J, nothing changing the value of J anywhere. And what we end up with is an infinite loop. Now, usually infinite loops are extremely dangerous, and they are the main cause of all programs crashing. But fortunately, this is Intellij. It has a built in protection for things such as that, meaning that it will never go infinity. It will slow down and will keep producing this output. But we never want to have this. We never want to have an infinite wire loop, and this could be a big problem. So we need to have some way to change the condition inside of this wire loop. So we have to have in here j plus equals one. Now when I write, click on, you'll see that we stop at 25 and we started with j at zero. These are the things that we always need to watch out for when working with a y loop. First of all, we have to have the initial condition right here. We have j equals zero. You cannot start your y loop without this condition. Of course, later on when we expand on this example, we're going to see more and more of this. But this is the main line that you have to toe when working with a Y loop. Second of all, you always have to have some kind of code inside of your Y loop that will change your condition to false. Meaning that J right now is less than zero. Less than 26, It's equal to zero. So we print out J, and then we increase J by one. Then again, and again, and again, and again and again until we get to 25. And at J equals 25, we increase it by one, it becomes 26. When we go back in here and we check, is 26 less than 26? No, it's not, it's equal to 26. And that is why we jump out of the Wi loop because this condition is no longer true right here. While a certain condition is true, we do some stuff and we execute some code. When this condition is no longer true, we exit out of our loop. That's the big deal about while loops. It's exactly like four loops with a few caveats added on top of it. Or meaning that we don't have a predetermined number. Of course, in this case we have, but sometimes the conditions will be different. I think in my opinion, while loops are more important maybe than four loops, they come in handy in a lot more places. They are more dynamic. So let's go ahead and add a debugger. And I want you to do this on your own and then come back to the video. So I will right click and I will debug. And actually, let me put this to five because I don't want to go through all of these numbers. So I will debug the code. And let's look at what happens. J right here, you can see it's equal to zero, while j is less than five. We jump in, we print out, we go back to the top. Now notice where we are going. We change the J. Now J is one, the condition is still true. One is still less than five, J 2j3j4. Now J is five. If we go into the wire loop, it evaluates it just like a normal if statement and it's not okay, so we just jump out of it. Ladies and gentlemen, this is your introduction to why loops. In the next video, we're going to be delving deeper into wire loops. We're going to see how we can use the break and why these two pairs, the wire loop and the break are such a powerful force. I will see you in the next video. Bye bye for now. 42. 10. Deeper into while loops: Welcome back my favorite python programmers. In this video, we're going to be delving deeper into wild loops. Before we continue on and create our new project, which is pizza toppings, our mini project, we need to understand a few things that are happening in here. Even though we've already covered these, I think it's important for us to take a closer look to properly understand what is going on. So first of all, as we've said before, we always need to initialize. We always need to be able to change the condition in here. And we also need to make sure that this condition actually ends. Now with this situation, we make sure that when it's while or while J is less than five, we will continue going through this. Now, some mistakes that can happen. For example, if you have right here the J shift at shift tab in order to remove a tab. Tab. In order to add an extra tab. You'll see right here, somebody might be looking at this and be like, nice, I mean, I'm increasing J, what could be the problem? The problem is that you're increasing J outside of the block of code of our loop. So it's very important that you know that the J is inside, that the condition is changing on the inside. Another thing that you will see later on is that sometimes we can say while true. If we have while true, it means that we will keep doing this forever. And you might be telling me, okay, how's this forever? What do you mean by forever? I mean forever. J will keep increasing forever. And how do we stop this? Well, in situations like these, we would have a condition in here that would say if j is less than, or wait, if J is greater than, I don't know, 12, we would break. If I write click and I run, boom, there we go. When we get to j equals 12, this condition becomes true. Or actually, when j is equal to 13, because 12, we actually print this out, j plus equals one, and boom, now we get this one, it's 13 and we break out. There we go, because 12 is not greater than 12. It's equal to 12. You can say greater than or equal to. And in that condition, we would stop at 11. These are things that you can play around. I do recommend that you play around with these conditions in here to properly understand. But as I told you, the true and the break work amazingly well together. And we're going to see more of that in the next lesson. But for now, let's delve a little bit deeper. And let's start creating our small little project in here which is going to be the pizza underscore toppings. So we're going to have a few available toppings available toppings. And they're going to be equal to the following. We're going to have, and I will hit Enter so we have more space, pepperoni duplicate with control D meet the balls cheese, the greatest, one of all, the most controversial one, pineapple. What do you think should pineapple be on pizza? It's a question I ask the students all the time. Should or shouldn't it be? Me personally, I don't mind. Why not have pineapple? Isn't tomato also on pizzas? Isn't tomato a fruit? That's also a very controversial topic. To see what I did there, I'm going to create the topic chosen and I'm going to set it to just an empty string. Now we want to keep asking a customer for a topping as long as he doesn't choose one of the non available toppings. For that, I'm going to issue you a challenge. Your challenge is to create a wire loop. I want you to create a wire loop that keeps asking for an input. The input should only stop when the topping is in the available toppings. You have to imagine what the condition on this wire loop should be. We will, we will keep executing the block of code that has input in it, while the topping it chosen is not in the available toppings. And a hint for you is the input should be inside of the wild loop block of code. And I should have warned you about the hint, but this is a fairly hard challenge. Very rarely do some of the students get this challenge. I think a hint is in order. Also, the condition should be topping chosen, not in the available topping positive video. Right now, I've given you more than enough hints. If you didn't take the hints and you were able to do this on your own, congratulations, you're doing incredibly well. If you needed the hint and you were able to accomplish it, that's great. If you use the hints and you were still unable to create this, then I recommend that you focus more on the things that we are doing positive video right now and go do the challenge. Welcome back. So first of all, we need to say, while, I mean this is the easy part, this should be done pretty simply while the topping underscore chosen, not in the available toppings. I'm going to say that the topping chosen is equal to input, choose a topping for your pizza. Then I'm going to say, hope you like replacement fields, replacement field topping chosen on your pizza. Now I will right click and I will run and choose a topping for your pizza. I want tomatoes, I potato. Okay, can I have some cheese? Yes, there we go. Hope you like cheese on your pizza. So while the topping is chosen, which is right here, is not in the available toppings, we will keep asking this question until cheese which is in the available topping, which means that this whole condition is false. Which means we jump out and we print out, hope you like topping on your pizza. So I hope you understood what is happening in here. Let's test it out again. If we, for example, type in meatballs, boom, there you go. Meatballs are available in the available toppings, or they are part of the available toppings, which means that we can actually select them, which means that we can make this condition falls and we can jump out of it. As you can see, using wire loops is a lot more dynamic than using a fore loop. For example, we cannot create a fore loop to handle something like this. We don't know beforehand how many times we want to ask for the topping. We will keep asking as long as the customer does not select one of the available toppings. So thanks so much for watching. I hope you enjoy it. And in the next video, we're going to be applying the strength and the power of the brake to our wire loops. So I will see you then. Bye bye for now. 43. 11. Break in a while loop: Welcome back my fellow Python developers. In this video, we're going to be breaking a while loop. We've already seen how a break in a Wile loop works, but we're going to be delving a little bit deeper. First of all, what we want to do is we want to give our user or our customer the ability to exit out of the topping choosing process. Obviously, if they are buying some kind of pizza and they type in a few unavailable toppings, we don't want to force them to keep going. We want to give them the ability to quit. So what we're going to do is in here, after they choose a topping inside of the wire loop, I'm going to say if the topping chosen is equal to quit, then I'm going to print out bye bye. And then we will break out. We click and I run, we come into the store like I want tomato, I want potato, I want a bird, I want chicken. I don't know why I said bird. I want some meat. As you can see now, the customer is like, okay, You know what? I don't want your pizza to bye bye, quit. We can just leave. It tells us bye bye. Then what does it say? Hope you like quit on your pizza? I mean, who likes quit on your pizza? Nobody does. But before we fix this issue, there is another issue that we need to fix. And that is if somebody is doing the tomato potato, and then you know what range they type and quit. You know, quit, quit. It doesn't allow them to quit. If they type and quit, it doesn't allow them to quit. And even worse, if they type in cheese, it's not working as well. Why? Because cheese has an upper case, quit has an upper case Q. And we are comparing these two values or string variables. The case is very important in here. We can only select cheese if we have a lower case. If we have even an upper case or any letter that is, as you can see, it does not register. We need to fix this. And when I say we, I mean because you need to use a case fold, make sure that we can quit however we want without having to worry about the case. Now, I do have a hint in here that will indicate how to do this, but I recommend that you posit the video right now and go do the research to find how to do this. There are different ways of doing this, three to one use case fold. Now, through your research, you might find some different method, Both work. Use whatever you want. Posit the video right now and go do the challenge. Welcome back. How did you get on with that? The important thing in here is to use the case fold right here on the topic. We will use the case fold, and now I right click. And if I type quit in range with all upper cases, it actually quits out of the program. Now the problem. Now some of you might have found lower, which lowers everything. Both good, both are the same. I prefer using case fold. If we run this again and for example, I type in cheese, you'll see that it still doesn't work. What should we do in here? Exactly? We can use the case fold right here. Now if I right click and I type in cheese, boom. As you can see we have this working. But there is a very important lesson in here that we can take advantage of even though two methods work the same. And I'm not talking about the case for all the ord lower you can use whichever one you want, it's the same. What I'm talking about is that even though we can add a case fold here and a case fold here in order to make it work, a better way is to add a single case fold right here, a single case fall on the input. Now if I run this, you'll see that I can quit, I can select cheese. Instead of using two case falls, I can use only a single one. And you'll see that it's not capital, which looks even better in the output. You need to start thinking about efficiency and effectiveness. Even though you can use two case folds, it's not as efficient as using a single one. Now of course, this case fold in here is not going to change the world. But still, when you're saving a few milliseconds over a loop, it makes all the difference. I want you to really hone in on this idea and think about it next time you're trying to write any coding program. Now obviously there is still one problem in here and that is that we actually get quit on our pizza and not good at all. Don't worry, we will come back to this later on when we learn about something called the Ls in a loop. And I will see you in the next video. Bye bye for now. 44. 12. Random Number Generator and Importing: Welcome back my fellow Python developers. In this video, we're going to be looking at random number generators and also have an introduction to importing. If you remember, we had created a guessing game a while back which involved guessing the Nicholas Flameles age. So we're going to use the same prospect or the same example, but we're going to be expanding on it because as you remember when we were working with the Nicholas Flamel age, we already kind of knew what the age was. And we had a very limited amount of tries that we can apply. Now we're going to have an infinite amount until we finally get it. And on top of that, the age is going to be random. I'm going to create a new Python file in here that I'm going to call Nicholas Flamel. And boom, I will right click on Nicholas Flamel and close other tabs. Which will close all the other tabs and all the other projects. And just keep this one. First of all, I'm going to import random. When I do this, it means that I am importing something called a module. The random has an entire library and you can even hold control and click on random to open that library. Now when I say library, it's a few lines of code of a few, maybe almost 1,000 lines of code. And as you can see in here, we have classes and functions and many, many stuff that we can use from random. Instead of typing all of this just to use maybe and range for example, we can simply import random and now we have access to everything that's in that random. A module is something that is already pre created, pre coded for us to use. Next we're going to create this actual he, we're going to have actual actual underscore h equal to random dot and in 120, if I hold down control and go to rand int, you'll see that we open the random pi, the module that we just imported, and you can see this is the rand in that we are using. Let me find the function. Where is it control? Let's try to find random, boom, there we go, returns a random integer. Let me open this up, actually, let me close this down. Rand end returns a random integer in range B, including both endpoints. So this is something very crucial to understand. When I wrote 120, it means that the 20 is included, so we're going to get a random number 1-20 Both are going to be included. Before we continue, I need to provide the highest H that this could possibly go to, and I'll tell you why. The highest underscore H is going to be 20 instead of 20. Right here. I will type in highest H. Next, I'm going to print out what is lamely in, here's what's Flames Weasley and I will give it this indicator to where the player type in the result, or actually we just have a print in here, we'll have the input in another place. I apologize. In here we are going to say that is between one and the highest age that the user, because remember, this is a random number. The user needs to have some indication, just for our own sake, so that we don't spend hours trying to guess this. We are going to print out the actual age. This, of course, is going to be simply for testing. Now that we've printed out or asked the user to provide us with the name, I'm going to issue you a bit of a challenge. Now you already have the code, so this shouldn't be a very hard challenge. All that you need to do is you need to create a wire loop that keeps asking our players, or our player for inputs until he gets the correct age. Keep the F statement inside the Wi loop and test if the player should go higher or if the player should go lower. Pass the video right now and go do each challenge. Okay, welcome back. What is our goal? We need to create a wire loop that keeps asking our player for an input while their guess is not correct. Which means that the condition should be while guess is different than the actual H. The issue in here is that we don't yet have guess. And this is of course natural because as we said, whenever we're working with wire loop, we need to initialize the guess, and in here, the guess will be none. And I will compact these a little bit because they are all over the place. There we go. While the guess is different than the actual H, this is the first thing that you should think about next in here. Keep the statement inside the wire loop, okay? Test if the player should go higher or lower, okay? The next natural thing to do is to actually get the guess input. So we're going to say guess is equal to input. That's it. We're going to have the input and just a small indicator in here. But the problem with this is that actual H is a random integer. And when we do this input, it's a string, we need to convert it into an integer before we can compare it with the actual H. Now that we have that, we're going to say if the guess is equal to the actual H, we should print out, you guessed correctly, ten points for griffin door. There we go. Else we're going to check if the guess is less than the actual. He will say, please guess higher L or else actually in this case we can simply use an L. Oh, sorry, print. Please guess lower is that correct? Yes, it is correct. There we go. Now, if I write, click and I run what is Flamel, age 12, please guess higher, 13141615. There we go. You guessed correctly, ten points for griffin door. And as you can see now we have an infinite amount of tries, unlike before where we had two or maybe three, I'm not entirely sure. But now our code works 100% And it's actually a good game. It's actually a game that you can give somebody to play. It's not like they have only one or two guesses, they have infinite guesses until they finally get it. Now, if you haven't done the challenge, because it was a hard challenge, I'll admit I want you to do the mini challenge that I'm going to tell you right now. I want the player to be able to go out of the game if they press the number zero. How would we stop the game if somebody presses zero? Positive video right now. Well you don't have to, but I recommend that you do this in here, just simply anywhere that you want. You can say if G is equal to zero, what do we do out? Hard luck, break now. Right click and run. 101126 00:00 P.M. hard lock, and we break out. Thank you so much for watching. In the next video, we're going to be starting a new big project, which is going to be the high Low. We're going to be learning a special algorithm just for that high low project. The next video, we will just be setting things up. Then we will learn bind research algorithm and we will create a really nice game where we will create sort of an AI. Not a complete AI, but it will be a program that will guess the number that you're thinking of in less than ten tries. How cool is that? So thanks so much for watching and I will see you in the next video. Bye bye for now. 45. 13. High-Low: Welcome back to my favorite Python programmers. In this video, we're going to be setting up our High low project. Let's go ahead and create a new Python file. New Python file. And I'm going to call this the High underscore low book. I will close this down for now. And I'm going to be typing in the following. First of all, the low is equal to one, the high will be equal to 1,000 We're going to print out first of all, the following. We're going to say that choose a number between low and hopes high. Then we're going to have the input which is going to be just press any key to start the game. Press any key to start the game. Actually, let's say think of a number. Think of a number 1-1 thousand. Now the player of our game is going to think of a number 1-1 thousand. The PC or the computer is going to try and guess that number. With a little bit of help. We're going to say, while true, I'm going to say that the underscore by underscore PC and what is that? The guess by PC is equal to low plus high minus low divided divided by two. Now you might be thinking, wait, Michael sub sub sub, what the heck is even this, Don't worry my fellow programmers. I'm going to explain everything in due time, but for now, we're going to get the high, low underscore input and it will be equal to input. This is the computer talking to us. I guessed replacement field. Then in here I'll also say press L to guess lower back. In here we'll also add a backslash N because we want to go to a next line then H to guess higher back, see if the guess was correct. And of course in here we're going to be replacing with the guess by PC. And this is the input that's coming in. I'm going to make it caseful, just in case the user tries to press the upper case or upper case or upper case. We always have those options. First of all, the player, which is me and you, or whoever is playing this game, will think of a number between the low and the high, which is 1.1 thousand. Then they are going to be pressing a key to start the game. So they press any key and they start the game. So they can start with the wire loop. We have this equation that I'm going to explain in the next video. And then we have the high low input. I guess this is the guess by the PC after they do this equation. My guess is this guess. So let's say you're thinking of a number, 800. The PC guesses 500, you have to tell it L to guess lower, H to guess higher, and see if they got the number correct. In our example. If for example the player was thinking of 800 and the PC guess 500, then the player should tell them H. So the PC can guess higher. If the PC guesses 800, the player says C, they guessed correctly. If the PC thinks of or guesses 900, then the player tells them L to guess lower. Now what's left to do is to actually create these conditions. And when I say it's time to create these conditions, it means that you should set the Lph conditions. First of all, create an F and Lip for each of the inputs. And the inputs I'm talking about, of course, are the LH and C. You don't need to write anything inside, just make sure you check for the inputs in the LF. Keep these empty. We're going to add the code later on. If you want, you can add something called a pass inside. Just type in BSS and it will help you, especially if you have errors coming up, but don't worry about that. The three options are L to guess lower and H to guess higher, and see if the guess is correct. Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? This should be a pretty simple challenge. We type in F high low input is equal to h. Then in here we are going to pass. What the pass allows us to do is it allows us to write this if statement because an if statement, let me just remove this, you'll see. And we hover over the error in the expected or it just says that it's expecting some code. You cannot just leave your if statements and your loops empty. You can add a pass just as a temporary placeholder. If the high low is H, L high low, high low input is equal to L pass. And then finally, live high low is equal to C. But finally, I apologize, we also might need an else in here just in case they write something completely different. But for now, I will keep it as it is. What? Let's just add the else right now. And I will print out, Please choose one of the following LH or C with a few exclamation marks. There we go. If I write, click and I run, think of a number, 1-1 thousand, press any key to start. Just hit Enter. I guessed 500. If I hit L, nothing happens. If I hit H, nothing happens. If I press, nothing happens, We just go through the wild loop again. And finally, if I hit three, for example, it tells us, please choose one of the following LHC. One more thing in here is I would like to add a space just so it's not crammed with the correct next to it. Okay, so also right here if we add, So let's see how that would look like. I just want to make sure that the output looks good. So press any key at edge. Okay, 12 maybe. Okay, so I think this would look very nice. Okay, there we go. Now at least we know where the prompt is for us to press the key. Ladies and gentlemen, we've just set things up. This part of the code should be very simple for you to understand. This part of the code should also be very simple for you to understand. The only thing that is weird is right here. And this is going to be part of the binary search algorithm that we are going to learn. In the next video, I will see you then. Bye bye from now. 46. 14. Binary Search Algorithm: Welcome back my favorite python programmers to a brand new video and kind of a hard one where I will require your full concentration. You might need to watch this video multiple times before you fully comprehend binary search algorithm, But that's the name of the game. You always have to show me complete concentration because I always need you to be on point. What is binary search algorithm? Let's imagine we have a class right now. We have eight students, I think, yes, eight students. But let's imagine we have 50 or 100, or 1,000 or 1 million. So we have this lovely teacher that wants to hand out report cards, so she has all the report cards in order. We have Abby Ben Sell, Pat, R, S, V, Z, so they are all ordered in alphabetical order. So what we want to do is we want to start giving these report cards out. So let's say we want to give van or Sam or whoever. Let's say somebody out of these three right here maybe. Let's say van. We want to give Van the report card. How would the teacher go about finding van? Well, the teacher knows that all of them are ordered in alphabetical order. What the teacher can do is she can start taking out Abby, then Ben, then sell, then Pat, and start going one name at a time until she finally gets to Van. Now this is not a huge problem because we only have eight students. But again, imagine if we had 1 million and Van was in the position 600,000 something. 600,008 So imagine the teacher has to go through every single 1,600,000.7 times in order to finally get to Van. Not very practical. And of course I'm taking things to the extreme, but there are situations like this. Like for example, trying to guess a number 1-1 thousand. So what the instructor does instead is something called a binary search algorithm. And binary search algorithm is something that we do on a daily basis without even knowing that we're doing it. What the instructor does instead is the instructor cuts the report cards in half. So she takes the Abby Bansal and Pat to one side and read Sam Van Zac to the other side. Now she doesn't select the numbers, she just separates them into two piles. And then she looks at the last name in the first pile. So she sees Pat, so she thinks, okay, so P is the last one. Which means that there's no way that van is in the first pile. So she discards the first pile. She's like, okay, great. This is amazing. Now let's look for Van. She does the same thing again with these report cards. So she discards tan Sam. Oops. And then she sees Van and Z. And she's like, oh, there we go. We have van. So instead of having to go through Abby one bend to sell three pad 45 Sam, six. Instead of having to go through six report cards, all that the teacher had to do was discard the first half of the pile and then the second half of the pile. So it only took her two tries in order to finally find van. And the same logic applies if we have thousands of students, just like we have in our example of the high low 1-1 thousand. Instead of the computer having to guess, let's say you were thinking of the number 800. The computer will start with a guess of 500, so it will split down the middle. What you can do is you can create a program that just adds one every single time. So 501, 5025035004567. And imagine if the player was thinking of a number, let's say 825. The computer would need to guess and the player would need to press 800 or no, actually, 328 times 500501502503. Imagine that It would take very long time. And it's not practical. And it's not a fun game, there's no thinking in it. But if we use the binary search algorithm, we can make our lives much, much easier. And that's where the equation comes from, because it always cuts in the middle. If I show you, you'll see that this equation always has whatever guess that we have, look, we have 1.1 thousand, so we guess 500. And you'll see this better when we start actually implementing it. But now I've created a small scale example to fully comprehend binary search algorithm. Now again, now I need your full concentration. Put your phone down, put everything down. I want you right here, right now, with me. So let's go ahead and get started. First of all, we have two rules that we need to follow. We will, plus one to the mid and make it the new low when we should guess higher. Okay, We add a plus one to the mid and make it the new low. When we should guess higher, we minus one to the mid and make it the new high when we should be guessing lower. These are the two rules that we need to follow. We are looking for number seven. This is the formula that we'll use. This will always guarantee that we cut in the middle. We start off with, in the beginning we have the low is one, The high is ten. We start in the beginning. The low being 1110, being high. The high is ten minus below, minus one divided, divided by two. What is divided? Divided? Why aren't we using a single division? Well, for the astute students that still remember the first section, when we use divided divided, it means we are disregarding everything after the float point. We are simply getting integers. When we use the divided divided, we don't want floating points, we want concrete numbers in here. We have high is ten, low is one, and the low is one. We have one plus ten minus one divided divided by 210 minus one is 9/2 It's 4.5 Because it's divided, divided, we disregard the floating point and instead of 4.5 we get four plus one equals five. Okay, Now we need to look at the rules. What is the rule? We got five plus one, the mid, and make it the new low. When we should be guessing higher, we're looking for number seven. Should we be guessing higher? Yes, we sold because we are looking for number seven. We got five plus one, the mid and make it the new low. What's the mid? It's five. If we plus one to it, it becomes six. We make it the new low. Six will become the new low. That's exactly what we do. Again, I will re explain this because it's a hard concept for people to grasp, but I will not explain it again, I will have to move on. We have the low one, the high ten. We apply or replace these into the variables and we get 510 minus one is 9/2, is 4.5 because we're using divided, divided, we get four plus one. It's 5.7 is greater than five, which means we should be guessing higher. If we look at the rules, we plus one to mid and make it the new low, when we should be guessing higher, plus one to the mid. The mid is five after we do the equation. And by the way, the mid is also the guess by PC. I'll add a comment in here. This is the mid as well, we plus one to the mid, it becomes six and we make it the new low. Now we reapply the equation, we have low being six, high being ten. We do ten minus six divided divided by two. Which gives us what? Ten minus six is 4/2 It's two plus six, it's eight. Now, should we be guessing lower or should we be guessing higher? Of course, we should be guessing lower because seven is less than eight. When we should be guessing lower, what do we do? Minus one to the mid. This is the mid. We do minus one. What's minus one? It's seven and we make it the new high. There we go. Now we have six as the low and seven as the high. But now again we apply the equation. Seven was the high, six was the low. Seven minus six, It's one, yes, Divided by two at 0.5 which means it's 00 plus six is equal to six. What should we be doing? We got mid. 66 is less than seven, we should be guessing higher. Plus one to the mid, and we make it the new low. And now we have the seven being the high and the low. Now we finally calculate seven plus seven -7/2 It's equal to seven. The correct answer is 7.7. Is the high, low. Some of you are dumbfounded Right now. You're looking at the computer, you're looking at your screen and you're like, what have I gotten myself into? I recommend you go through this video slowly. You think about every single step and if you have any questions, always refer back to one of the instructors or to me. Thank you so much for watching. I hope you enjoy. And I will see you in the next video where we will be completing our game using the theory that we did right now. Bye bye. For now, please make sure to understand this because you will have a challenge. Keep that in mind. You don't have a challenge now, but you will have a challenge. Next video. Bye bye for now. 47. 15. Completing our Game: Okay, so now it's time to replace our pass with some real code. First of all, we need to change this pass or we need to fill in the information in here. We need to understand what we are doing. Just like we saw in the previous video. Let me take you back to the rules. We plus one to the mid to make it the new low when we should be guessing higher. And we minus one to the mid and make it the new high when we should be guessing lower. Our main goal is to translate this or these two rules into code. How do we do that? I want you to take a moment and try to do this yourself. You should be, you should be able, I will be so proud of you. If you can do this back in our code, I hope you made me proud back in our code and here, first of all, we need to handle what happens when we should be guessing higher. Remember here, plus one to the M, plus one to mind. And make it the new law when that's it, when we should be guessing higher. Okay. In here, first of all, we take the mid. And again, I told you that the mid is the gas by PC plus one. We make the new low. Now the low is equal to the guess by PC plus one, when we should be guessing lower minus one to mid, and make it the new high is that correct? Let me double check. We should guess. We make it the new low. Yes, and we make it the new high. Okay. In here we get the guess by PC. We do a minus one and we make it the new high. Then in C or LF, we type and we simply print out, I guessed it, with an explanation mark. Also, we should break because we don't want any more guesses. That is basically it. I hope you were able to do this. If not, it's okay. As long as you clearly understand what is happening, let's go ahead and test this baby out. If I read, click Run, Think of a number. Let's think of 720. The 3,700.23, Let's start the game. 723. You should guess higher, huh? 750. So you should guess lower, 625 guess higher guess, higher guess, higher guess, lower guess, lower uh huh, guess higher, lower, 23. 723 hit. Nice. I guessed it very nice. So how many times did it take it to guess? So this is the first guess. So 1-234-567-8910 And there we go. So it took our PC ten guesses to finally get it. Imagine if we were simply increasing this by one, we would have needed or 723 -500 that's 223 guesses. Instead, it only took ten and you want to know something crazy, the maximum amount of times that it needs PC to guess, the number is going to be ten. To prove that, I'm going to issue you a challenge. And your challenge will be to create a counter count the number of times the PC tries to guess, create a variable outside the wire loop and initialize it and increase it every time the PC doesn't guess correctly and print out the number of guesses. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? First of all, we need to create the number of guesses, and we do that outside of the loop. In here, we'll say number underscore, underscore guesses, and it's equal to zero. Then we need to increase this number by one every single time. And where do you think we should do that? Try to guess. Well, we should do it anywhere for that matter. Some of you might think, well, we should do it here and here. But it doesn't matter as long as we take a guess. It should be in here in the number of guesses plus equals one. So let's go ahead and test out 723 again. Where do we printed, where do we print it? I guessed it in replacement field number of guesses. Of course, we should do it here when we actually get the correct answer. Right click and run 723. Let's go higher, lower, higher, higher, lower, 23, lower, lower. Boom, There we go. I guessed it in ten, choose any other number, Let's try something low. Let's try 300 or 250. 250 is very simple, because 500 divided, for example, let's say 250. Boom, there we go. Just took it to. Let's try something a bit more complex. Red and red and 68, I guess. Lower, 168, higher, lower, higher, lower, higher, 68, higher, lower, boom. Ten guesses. How cool is that, ladies and gentlemen? Thank you so much for watching, but there is something extra in here that we still haven't finished with. I will tell you next time because we have one more lesson to do, and that is the L statement in loops. And then we will use this L statement in a very powerful way. It will blow your mind, at least it bloom my mind when I first did it. Thank you so much for watching. I will see you in the next video where we will learn about L statements in loops. Bye bye for now. 48. 16. Else statements in Loops: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be talking about the L statements and loops. Let's go ahead and create a Python file. A new Python file, and we're going to call it lo in here, I'm going to create a list. And that car list is going to be the following. I'm going to have BMW car. Come on, I'm going to have Ferrari. I'm going to four car, I'm going to have a car and the Tesla car. Nice. There we go. This is in no shape or form. We are not sponsored by Tesla, we're not sponsored by anyone. But if they do watch this video, I'm always open to suggestions. I will change all of my examples to accommodate your car without any further ado, Let's go ahead and create a for loop that will go over all of this list. Car list, I'm going to say car. Watch carefully. If the string car not in car, I will print out this list is acceptable. If we don't have car in every single car in our car list, then this list is unacceptable and we will break out. What do you think the output is going to be as soon as I run this? If I write, Click and I run it, tells me, sorry, this is unacceptable. And by the way, when I tell you, what do you think the answer is going to be, Please take the time and actually don't just run and look at the answer, think of what it is going to be. So, as you can see, if we run, it is not working and we are breaking out. Why is that? Because Ferrari in here does not have car in it. But if we add this car and we write, Click and we run, excellent, we don't see anything. And that's not good because there's nothing being output, we don't even know if this car is, this list is acceptable. You might be thinking, well, you know what, Michael, I can just add print this list is acceptable right here. The problem with this is if I didn't have the car in Ferrari, I would have, this is unacceptable, this is unacceptable, and this list is acceptable. There's a cognitive dissonance in here. What we have is something called in L for our four loops. So if we don't break out at any point, then we have this printed out. Or if we finish normally through our list, then we go into the Ls and we print out or execute whatever code is inside. For example, right now if I run, you'll see that we only get, sorry, this is unacceptable, Why we don't execute the Ls? Because we've broken out of this list. If we have car in here instead, in the Ferrari, you'll see that it tells us that this list is indeed acceptable. Why is that? Because we went through the entire list. We haven't broken out of it, so we go into the and that's basically it. There's nothing too much in here. Just remember that if the loop finishes correctly, then everything works good. Thank you for watching. Now as a small challenge in here, I want you to go back into into where is our pizza topping, the pizza topping in here. I want you to add an L statement to this while loop in here so that we don't print out. I hope you like quit on your pizza. How would we fix this? I hope you tried your best in here. I will add an L. I will add the indentation. What happens in here if I right click and I run, choose a topping for your pizza. Let's say we want kale, doesn't help. Tomato. Uh huh. There we go. Still doesn't work. Cheese. Boom. Hope you like cheese on your pizza because we haven't broken out of our while loop. We just go into the else the oil has done its job. If I now try, for example, tomato potato. You know what? I just want to leave quit. It just says bye bye. And we don't have hope you like quit on your pizza, which just sounds weird. Nobody likes quit on their pizza. So thank you so much for watching. I hope you understood. In the next video, we'll be using our high or we'll be using the L in our high low. And I think it will be the last video in this section. Congratulations on making it this far. Please leave me a review wherever you can, and I will see you in the next video. Bye bye. 49. 17. Else in High-Low: Welcome back my favorite Python programmers to a brand new video. And this one we'll be implementing the L in our high low. Let me take you back in time to when we were explaining the high low. In here, you'll notice that we start off with a low and high. We find the mint, we increase by one, We get a new low or a new high. We get the mint, we get the mid, et cetera, et cetera. And then at the end, sometimes we have the school feature, if we don't guess the number beforehand, if it takes ten guesses, we actually have the high equals the low. And this is called the high low. And when we have a high low, we have the answer, so we don't have to guess more than that. What we can do is we can create an L statement in some way or modify our code in order to have an AI that will be always checking if the high is equal to the low. If it is, if we have the high equals to the low, it means that the answer is the correct answer and it's equal to either the high or the low. I want you to use that information in order to do the following challenge, L to a while. Change the condition on the while loop to stop when the high is equal to the low. This is something very important. You will have to figure out the condition. You should stop when the high is equal to the low. Add an L statement for when the loop finishes. I'll give you a small hint. If you don't want the hint and you want to conquer this on your own, pause the video right now and go to the Challenge 321. The while condition should be high different than low. Pause the video right now and go do the challenge. Okay, welcome back. So first of all, let's go back into our high low. The condition in here is not going to be just true. It's going to say while the high is different than the low, we're going to be doing all of this. Then at the end, I'm going to keep the break in here because it's still required. Maybe the computer guesses your number without getting to the ten in here. I will add an L. I will say print out you were thinking of replacement field the high because it doesn't matter. We can either use the high or the low in here, it doesn't matter at all. We will also print out it took me replacement field, number of guesses. If I write click and I run in here, I'm going to say 500. Let's think again to 723 because it took us ten guesses. High, low, high, high, high, low, 23, low, high, low. Look at that. I didn't press C, and it told me that you were thinking of 723. As you can see, this is magic. But the only problem in here is that it says that it took it nine guesses. If we count them and remember it is, then let's just double check. 1236789. There we go. 123-45-6789 The last one is not a guess. Keep in mind the last one is not a guess. It just told us that you were thinking of 723. This is not incorrect. It just, it didn't guess, it knew that you were thinking of 723. Let's try a different number. Let's try 628 high, low, high, low, low, low. There we go. Now, it guessed 728 before it guessed it on its own, because it was less than ten. I guessed it in eight. Let's go back and count 1235678. And there we go. So ladies and gentlemen, I hope you enjoyed This is a very fun game that we created. It's a very complicated, not complicated. It's a fairly complicated program or project that we made. Thank you so much for watching. Thank you for sticking with me until the end of the section. Later on, we will be appending the section with more examples, with more projects down the line. I will always keep this course and master class updated. I will see you in the next section where I think where we will be looking at lists and couples. The things that we already kind of looked at when we were working right here. But in much more in depth. You'll see that this is a very powerful tool. Thank you for watching and I will see you in the next video. Bye bye for now. 50. Section 5 - Lists and Tuples | 1. Introduction to Sequence Types: Okay, so let's go ahead and start creating our project. First thing we'll do is on this window, I'm going to click on New Project, right here at the top. I'm going to go to next. I'm going to call this Project List and Couples. I'm going to save it. Inside of code, I will write click Create a new folder, and I shall call this Lists and Couples, Okay? And save it in there. Once we hit Finish, we should see the following window. Before getting started, let's understand what sequences are. We said that this is an introduction to sequence types and lists. Let's start by understanding what sequences are. What are sequences? A sequence is a collection of items. We've previously seen something related to that when we talked about strings. These are also collections of items. In the case of a string, the items are just characters. In the case of lists, it could be anything. The items could be strings, the items could be integers. The items can even be lists. So it could be a list of lists, and we'll see that later on, that is called Nest blists. Next, we know that each item has a position and items are in an order. Just like when we talked about strings where we had the first element indexed to number zero or the index was equal to zero, the second element was index one, et cetera, et cetera. The same things hold true when we are talking about lists. Each item has a position and they are in an order. You can refer to any item in the sequence by using the index number, Meaning, let's say we have a sequence that is called S. We can access the item at index zero using these two square brackets. We can access the second item which is on index number one. The same way in here. This is not something that's completely new to you. You've already seen how we can access the individual items using a string, using the square brackets. I will continue on, and let's also understand that in Python, the sequence also starts at index zero, not at index one. This is very important to remind you of sequence types could be lists, byte arrays, strings, topples, and ranges, and bytes. Now we will see couples later on. We've already seen strings, we've already seen ranges. But you might not have known that that was a sequence. But it is. We will see bays and bytes in later sections. Finally, Python classify sequence types as mutable and immutable, and we're going to learn what these two things are and understand that later on. Let's go ahead and get started to properly understand how lists work. I'm going to go back into my coding here and I'm going to create a new Python file that I'm going to call lists Underscore Intro There we go. First thing I'm going to do is I will close this project down to have more space. And I'm going to create the color underscore parts equal to, I will start with wheels just in order not to have a very long string in here. I'll just add enter and then enter. And I'll just try, start writing things down. I'm going to duplicate control D. I'm going to have tires control D. Seats control D. Doors control D, and stereo both. There we go. And unlike other languages where if you're at the end of your list, you are not allowed to add a comma in Python. Because as I told you, this is a very versatile programming language. You can actually just leave the comma there in case you want to add another item, or if you want, you can remove it. I personally, personally like to keep it because in my experience, since I was like a kid and I've been programming, it's always been a freedom issue for me. Like why can't I leave a comma now? I can, so I will, then I'm going to create a four loop to iterate over this list. So I'm going to create four. Part in car underscore parts and I'm going to print out the part. If I right click and I run, this is the output that I will get. I'm going to dock it right here on the right hand side. As you can see, the fore loop using the part variable iterates through every single item that we have in our car parts list and then it prints it out. As you can see, wheels, tires, seats, doors, and stereo. Nothing too much in here. We've already seen this. We weren't using lists, but we were using strings. It's the same concept if you want, I encourage you to go through this using the debug. Next, I'm going to go ahead and add a small print in here, just an empty line. And I'm going to print out car parts at position number two. Now before I run, I want you to take a moment and try to guess what the output is going to be. I'm going to write click and I will run. And there we go, I get seats. Because if I go and look at the car parts, I can see that we have wheels at zero tires at one, and seats at position number two or at index number two. To be more precise. My warnings, as you can see, that is the output that we get. We get the seats. All right, so I hope you understood what is happening here. If you have any questions, you can always leave them in whatever section is available. I'm going to issue you a bit of a challenge to do on your own. So you'll need to print out a slice because remember, just like we can print things using their index, just like we saw right now, or print items out using their index, We can also slice them just like we did with our strings. So this should be simple for you. Use slices to print out the first three car parts that we have. Print out the last car part using two different indexes. And that's it. That is your challenge. Pass the video right now and go do the challenge. Okay, so how did you get on with that? First thing I will do. Okay, sorry for that. First thing I will do as I'm going to just add an empty space and I'm going to print out the carport at positions going from zero to dots three. So if I write Click and I run, there we go. As you can see, I printed out the first three items. Now some of you might have done the following. You did not specify what the starting position is, so naturally it will start at index number zero. If you did that, I congratulate you. You've been paying attention to the score so far. Next, I'm going to print out the car part. As we said in the challenge, we wanted to print out the last car part using two different indexes. The first index would be pretty obvious. So we have 0,123.4 at index number four. I should see stereo. There we go, it works. Now, what about the other method? Some of you might have done the other method before this first method. Some of you are adaptive like that, but the other way around, and if you haven't figured it out, I do recommend that you try to go back to the previous project where we were accessing items or to be more specific characters in a string, because this is a very fun challenge. So we can use the minus one. If I do minus one and I run look at that, I also get the word stereo. And I will duplicate this just so we know that it is indeed the same. Look at that. Stereo and stereo. So just like with strings, we can access items using negative indexes in a list. It's basically the same thing. Strings are actually sequences as well, but the difference is that strings are immutable. And we're going to see what that means in the next video. I hope you enjoyed as a small homework, I recommend that you go through this for loop using AD Bug. And I will see you in a few seconds, hope you enjoy it. 51. 2. Immutable Objects: Okay, so as promised, I told you that. I'm going to tell you or explain to you what are immutable objects. Let's go into our slides and let's talk about immutable objects. Immutable is when no change is possible over time. That's the actual meaning of the word Python. If the value of an object cannot be changed over time, then it is known as immutable object. Once created, the value of these objects is permanent. They will stay with the same value forever. Let me give you an example of what an immutable object would look like. I'm pretty sure that you are going to be very surprised. First of all, an immutable object is numbers. Like integers, floats, or bullions. We cannot change an integer object once it's created. When I say object, I also mean a variable. Another thing that is immutable are strings. Strings once created cannot be changed. Now, I think some of you right now are thinking, oh my God, wait, wait, wait, wait, wait. You're telling me that we've been changing strings the whole time. For the past, I don't know, like four or 5 hours we've been changing strings and now Michael, you're telling me that I cannot change strings. You're telling me that strings are immutable. This has to be some bull do. I will show you how strings can't be changed in just a bit, but before we do that, we also need to know that couples are also immutable. And we will learn more about topples later on. Let's go into our code and start creating immutable objects. I'm going to go back into my code in here and I'm going to create a new Python file that I'm going to call immutables. Now, before I start talking about immutables, I need to show you something very important in here. Let me search for what is ID in Python or what is the ID function in Python. Right here you'll see the Python ID function returns the identity of an object. The identity of an object is an integer which is guaranteed to be unique and constant for this object during its lifetime. Two very important keywords in here, unique and constant. Unique and constant, which means that no two objects can ever have the same ID. And that the object, once it has an ID, it will stay constant during its lifetime. It will not change, meaning that this will identify that we are indeed talking about this specific object. It's very important for you to remember unique and constant. Let's go back into our code. In our code, I'm going to type in the following. I'm going to say that we have a value that is equal to six. I'm going to say that we have another value that is equal to value. In here, I'm going to do the following. I will print out the idea of value. I will say ID value. Duplicate this line and the idea of another value and then another value. Let's see what the output is going to look like. If I write Click and I run, look at that, I get the following. And I'm actually going to remove the spaces in here because when we're providing multiple arguments, multiple arguments, because we have a comma in here, it adds a space on its own. So when I write Click, that looks a bit cleaner with only one space. So as you can see, we have this ID number that is unique to both of these variables. Well, you might be saying, wait, wait. Didn't we say that the IDs are unique? Well, yes, they are unique to each object. Which means that these two things in here, or these two variables, or objects to be more specific, are indeed the same. Now these are random IDs. You might be getting different IDs than what I'm getting. As you can see, every single time I write click and I run, I get a different ID. Now you might be also asking yourself, where does this ID even come from? I'm not going to delve too deep into what all of these IDs mean, but what you should know, it's a combination of a random number and the space that each variable takes out of your Ram. Rams have like 2 gigabytes, 4 gigabytes, 16 gigabytes, whatever. Every single time you create a variable, you get a small slice on that Ram. That slice has an ID of itself. It's combined with a random number and you generate the following. On your ramp, there is a specific place for integers, specific place for a strings, specific places for lists and arrays and so on and so forth. But this is outside the scope of what we're learning today. All that you need to know is that both of these have the same idea. Which means that they are the same object. But now I'm going to try and change this. And remember I told you that the integers are immutable, they cannot change. I'm going to print out just an empty line in here, and I'm going to say that value is equal to four. And I'm going to print out the following. I will duplicate this line of code and I will move it down. I moved it down, holding down control and shift. Now look at what's going to happen. I will write click and I will run and look at that. As you can see, this ID is different than the one we started with. Look the last two numbers in here. We have 88 and here we have 24. Oh my God, what happened? Well, we try to change value, and when we changed value, the ID changed. And what does that mean? That means that value now is a completely different object, because integers are immutable, which means they cannot be changed over time. When we actually try to change them, it works. But as you can see, we get a totally different ID, which means we get a totally different variable, a new variable, value has been created. There you go. If I try to print out another value, take a few seconds, pause the video. Or if you want, just think about what the output will look like. Don't, don't run it. Think about it. If I right click and I run, there you go. You can see that the idea of another value stays the same as value and another value. Because remember now value is a completely different object, so it should make sense. Okay, let's continue on, and let's test it out on a string. Because you might be saying, well, yeah, actually you said value is equal to four. But what about, let's say, when we append something that shouldn't affect the strings, I'm going to print out just an empty line. I'm going to say message equals to correct. Because you are correct, I'm going to say underscore message is equal to message. Then I'm going to print out, or actually I'm just going to duplicate these lines. I'll move this down and I'm going to say the idea of duplicate this message, another message. Now when I write Click and I run, as you can see, we have different IDs for the message and another message. Obviously they start, they might look similar for the first few couple of numbers, but obviously they later on change. So you can see right here, 880, right here, you can see 368 and so on and so forth. Nothing to wind in here. The idea of the message is the same as the idea of another message. And that was expected, but now we are going to break this. By we, I mean you, because you will need to add to our value, append the value of our string. Do that before printing out the idea again. And then run and look at the result that we get. What does it mean? You should know by now. I will give you a small hint. If you don't want the hint and you know how to append the string yourself, or you want to look it up, then go ahead and do the challenge. If not, I'm going to give you a hint, 321. Boom. To append, you can use the plus equals pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? As you can see in here, we have message equals correct. We printed out the ID's. Now, I'm going to try an appendix. I will print out appending the message now with three dots. So that in the output we can see like, wow, what's happening? But now nothing's actually happening. We'll just have a print in here. I'm going to print out, sorry. I mean, say that message plus equals ish. So you are correct ish. I will print out message, so what it has become. And I will also print out the idea of message. Let's go ahead and print out the idea of another message. Why the hell when I write click and I run, I got the ID in here where it's 2398064. Then I said appending the message. Now it's correct, is now the ID ends with 61128064. As you can see, the ID changed when the variable changed. And what does that mean? Let's say it altogether. Yes, exactly. A new object was created when we tried to change our strings, because strings are immutable, When we changed the result or the value, Python actually created a new string to accommodate this new value. I hope you understood what this is all about. I know it might look like freaky black magic. This is Python works, and you'll see that this has a lot of benefits, especially when we start working with mutable objects. In the next video, I hope to see you there. I hope you enjoy, and I'll see you in a few seconds. 52. 3. Mutable Objects: Okay, so now it's time to start talking about mutable objects. What are mutable objects? Mutable is when something is changeable or has the ability to actually change. In Python, mutable is the ability of objects to change their value during round time. Which but does that mean? Which means that their ID should stay the same. These are often the objects that store a collection of data. Just like lists that store a collection of data. Example of mutable objects would be lists, sets, and dictionaries. And we're going to learn about sets and dictionaries in later sections. But for now we're going to focus our attention on lists and see how they are actually mutable. If you go back into our code, I'm going to create a new Python file. And sometimes if you don't see the file, you can click on the actual code in here, go to file and create a new Python file that I'm going to call the mutables. The mutables, I'm going to create a shopping list. A shopping list is a great example of an object that we would like to change. Because I don't know if you go shopping yourself or if you just order. But the same thing holds true when you're ordering items from Amazon or the supermarket or whatever. You start adding items, but then you also might want to remove these items. So there will be a lot of change. A shopping list is a perfect example of an object that we would like to be mutable. I'm going to have milk. I'm also going to set it on a new line, and this new line doesn't look nice. Shift up until the end. Duplicate this. Now with the milk, I'll get pasta and some eggs, maybe. Maybe I'll get spam bread. I hate spam, by the way. And rice. There we go. This is our shopping list. I'm going to say that we have another underscore shopping underscore list that will be equal to our shopping list. I'm going to print out the ID of shopping list. List two.com ID shopping list. Duplicate this. Another shopping list ID, another shopping list. If you right click and we run the same output that we were expecting. The same ID is there for both the shopping list and shopping list, because they are the same. We've set them to be actually the same. So I'm going to give you a challenge. Your challenge will be to append our list. So you'll need to append the value of our list. Print out the ID. Again, run and look at the results that we get or the result that we get and what does it mean. But before you start your challenge, I should give you a hint. If you want to go and understand how to add or append a list yourself, I do recommend that you try it on your own. You will find that there could be some freaky stuff going on in there, but my hint is 321 to append use plus equals and not just the normal double quotations, but with the square brackets around them. Pause the video right now and go do the challenge. Okay, welcome back in here. What I'm going to do is I'm going to append my shopping list. I'm just going to print out and then print out adding cookies. Is that how you write cookies? I hope so. Adding cookies with three dots. And I'm going to get my shopping list and say plus equals. Now this is where most of you might have messed up. Some of you, if you didn't look at the hint and you tried it out yourself, you might have a cookies like this in here. I will print out the shopping list again. So print out shopping list and I will duplicate this and take it down to the bottom, the idea of the shopping list. So I'll actually jag this and put it at the bottom. If I write, click and I run, look at what I get. So I get milk, pasta, egg, spam, bread, rice. And I also get C, 00 K, E. And what the hell is happening? Well, what is happening is that cookies, as we said, is a string. And as we alluded to earlier, strings are also sequences. What that means is that C is an item, O is an item, is an item, k is an item, is an item, et cetera, et cetera. When shopping list, which is a list, is plus equal this other sequence, it thinks that it should take each individual character and consider it an item and add it to its list. Instead, what we should do is we should tell it that cookies is an item on its own. So now if we write and click and we run, you'll see that we actually have cookies being added. I hope you understood why that is the case, how this changed. But the more important thing in here is the ID. What happened to the ID? The ID started off as 24588, whatever, and then 792, and then it stayed 792. Oh my God. What does this prove? This proves that we were actually able to change or pend or whatever, changed the value of our shopping list, of our list, the ID stayed the same, which means no new object was created. Which means that a list is a mutable object, while strings, numbers, bullions, et cetera, are all immutable. If you try to change them, the value of the ID will change, which means a new object was created. So I hope you understood the difference between an immutable and immutable object. I hope you understood the benefits of having mutable objects, and the benefits also of having immutable objects. I'll tell you the benefits of having immutable objects. And just a bit, I actually have a table in here that I almost forgot about. Immutable objects are quicker to access because you know that this object will never change, it will always have the same position in your data based on the Ram. I'm not going to go into specifics, but because it doesn't change, it's easier to access. Mutable objects are recommended when there is a need to change the size of our current content of objects. Meaning if we have a list of groceries that we will definitely change later on. Extend, shorten, then mutable object is the way to go. Immutable objects are expensive to change. Why do you think that? Take a moment to think about it, because if you try to change an immutable object, you actually have to create another immutable object which is heavy on the system. You might think like, yeah, what are you talking about? Like I just changed the list or changed the string and it happened like instantaneously. But when you have a program that is thousands of lines of code, when you have, I don't know, like millions of objects being created, it's going to take it stole. So knowing which object to use is very important. Mutable objects are easy to change, unlike immutable objects, which are expensive. And finally, when we talk about immutable object, a change involves the creation of a new copy, wh. When we talk about immutable objects, change can be done during run time. That is the benefit mainly of using immutable objects. They are quicker to access. If you have an object that shouldn't change its value over time, using an immutable object is the better option. So I hope you enjoyed, I hope you understood what this is all about. I do recommend that you go and look yourself into these things. I might even attach some homework, some quizzes to these videos. We'll see what happens. So I will see you in just a few seconds. When we talk about binding multiple names to a list, what is that even? So I'll see you in just a bit. 53. 4. Binding Multiple Names to a List: Okay, so let's look at binding multiple names to a list. Now, this is not a role in Python. This is just an experiment to show you what happens when you have mutable objects. Just as a small introduction, what I want to do in here after printing out the idea of shopping list is that I want to actually out another list. I'm going to print out in here. And I'm going to say this is another list. I'm not printing out the idea of another list. I'm actually printing out the entire another list, another list. Let's just call it another shopping list. I think you are going to be a little bit shocked of what you will see. I'll also copy this pasted in here, and I'll say that this is the shopping list and another shopping list. Okay, there we go. Let me move this up a bit and I will just print so that the ID is separated from. Oh, and also, let us why not print out the other shopping list ID since we're here. If I write Click and I run, look at what we get. So we are adding cookies, and remember we added cookies to our shopping list. We did not change another shopping list. And notice what we get in the output. This is another shopping list, and what do we have at the end? We have cookies. Oh my God, what is this all about? Well, remember, another shopping list is pointing to shopping list, which means that they are the same object. We've already established that when we changed or when we checked the ID. But now as you can see, when we changed the shopping list, because another list is pointing to shopping list, they have the same ID, they are the same object. And we said that shopping list is a list, which means it is mutable, which means when it changes, another list will change with it. As you can see, the ID has stayed the same for the shopping list. For the another shopping list. Every single time you make changes to shopping list or another shopping list, the change will be on both lists. Kind of crazy, I know, but this is how Python works. So just to hone in the idea, I'm going to issue you a bit of a challenge. Your challenge is going to be to add bananas. So you need to first create another four lists and set them as the another list. So a lot of students make the mistake of creating list a and then list B, and then no, you should say a equals b equals equals D equals equals F. No matter how many lists you want, equal to another list, then print out, then let's see, append another item to one of the four newly created lists. Use the pen with something inside. This is a different way of appending. If you don't want to use the plus equals, print all of them out and what do you see? You should be already familiar with what the output should be, but test it out for yourself. Pause the video right now and go do each challenge. Okay, in here I'm going to go ahead and create a few more lists. I'm just print out an empty line. I'll say a equals b equals equals equals equals f. I'm going to say that all of these are equal to another shopping list. Then I'm going to print out list just for the heck of it. I'll then say that I want to add bananas. I'll actually add bananas. First of all, is that how you write bananas? If I write click Show Context Bananas, it only needs one on each side. Bananas adding bananas to a list B. Just so we are clear on that, then I'm going to say B end. I will add bananas with one on each side and print out, print out, print out another list. Print out the original shopping list. Print out whatever you. Because when I write click and I run, as you can see, bananas after we've added it to only the B, all of them became the same. Because these are mutables, they are linked to the same list. Which means when we add banana to one, we add banana to everyone. So as you can see, when one list changes, all of them change. So I hope you enjoyed, I hope you understood. And in the next video, we are going to look at some common operations that we can use on our sequences. See you in a few seconds. 54. 5. Common Sequence Operations: Okay, let's continue on and let's look now at common sequence operations. I'm going to open up a link in here that I'm going to provide you with. Here it goes. This is the documentation, Python.org library, STD type, I think it stands for Don standard library and the built in types. Once you get to the link, I will do a control to find and I will search for common sequence operations. There we go. Now some of these operations you might have already seen. If you look in here, you can see that x in returns true. If an item of is equal to x l, we return false. We've already seen this used many times in if statements when comparing two strings. We also have the X naught in which returns false if an item of is equal to x. We also have concatenation, just like we were able to add two strings together to concatenate them. We can also add two lists together with the plus sine. We have the multiplication which creates or multiplies the sequence, which in our examples were always strings multiplied by an integer, would just duplicate that string multiple times, as you can see in here. We can also access an item with the bracket. We can slice, slice our sequence using the square brackets. We can slice the sequence using a step using the square brackets. We have the length, I believe we've already seen that one. It just returns the length of the S or the number of items that we have. Keep in mind that this does not consider the index starting at zero. We don't count them like 012. If we have, for example, a sequence that goes 0-7 that means we have eight items. Next we have the minimum which returns the smallest item, the maximum which returns the S. And this overcomplicated index thing, which if you just take out everything on the side and just leave index x, you provided with the item x. And then this method, or this function, or this operation to be more precise, returns the index of the first occurrence of x in. Finally, we have the S dot count operation, which returns the total number of occurrences of x in. How many times did we, let's say we're looking for banana, how many bananas are there in this shopping list? You would use the doct. Okay, So pretty simple. Not too much in here. I recommend that you go through them. You understand every single one of them. We've seen them before, and now we're going to look at a few of them in our program. I'm going to open up by lists and doupples. I'm going to go into again, the Python is there, so I click on the code Python file new, and I call this the numbers underscore lists. Let me close this one down. I'm going to create random underscore numbers, and it will be equal to 162-51-2068 I will duplicate this and change from a small to big numbers. And the numbers that I will have in here are 695-41-2365 7,584, And by the way, these are just random numbers. Just recommend you find high random numbers, or big random numbers and small random numbers. Then I'm going to print out the minimum of the small numbers. I will duplicate this and change it into the maximum. I will then select these three lines including the empty space, and then duplicate that as well. And then we will use these for the big random numbers. All right, so with that out of the way, let me write click and run, and there shouldn't be any surprises here. The smallest number in the random small numbers is one. The biggest one is 68. The smallest one in the random big numbers is 365. And the biggest one or the max number is 7,584 Nothing too important in here. We simply used a very common operation that gives you the minimum and the maximum. This was just a demonstration. Now, with that knowledge in hand, it's time for a bit of a challenge for you. You need to test out other methods or operations I've used. The word operations may be, print out the output of the method length on our two sequences. Print out the output of the method. Do count on the string with the same letters appearing multiple times. What do I mean by that? Ferrari. Ferrari has the letter R appearing multiple times on it. You need to use this Ferrari because remember a string is a sequence as well. You will use the count on Ferrari and count how many times we had occur in there. Pass the video right now and go do the challenge. Okay, welcome back. So, how did you get on with that? The first part of our challenge was to print out the length. So I will print out length of small numbers, print out the length of random big numbers, right click, run, and there we go. We have five by five. Notice 16 would be at index number zero, correct. Then 123.4 But in this case, even though index stops at four, we have 12345 elements. 12345 elements. Just to test this out, I'm going to create an extra element. So we should see that the length of random big numbers should become six. There we go, we get a six. For the other part of the challenge, I'm going to add an empty print, and I'm going to print out Ferrari. Do and I will count the number of Rs that I have. If I write, click and I run, I should see that we have three R's in my Ferrari. Maybe some of you created like something like this message equals Ferrari. And then you message in here on the dot, that is the same exact thing, but I decided to use it explicitly. Explicitly means I don't store it in a variable, I immediately the count on it explicitly. All right, so a small trick before we leave. This is a very simple I think, lesson in here. So I'll give you a small extra challenge to mess with your head if I try to do the following. If I want to print out Missy P dot count and I one account SSI. Notice that we have MISSI on here and also we have SSI on this side. How many will it count? Will it count two or will it count one? If I write click and I run look at that, it only counts one of them. Because if you look closely into what this says, the total number of occurrences of S, even though it doesn't explain it really well, once it finds one of them, it doesn't consider the second one to be part of it as well. Meaning that it counts this one and the other one would be just an S I. If you wanted, you could have done the following. Now, this should count or return at least two. There we go. So just something to keep in mind. I hope you enjoyed this was, I believe, a very simple lesson, I hope you enjoyed. Operations will come and will be useful in the future. In the next lesson, we're going to learn about operations on mutable sequences. And a pending our lists where we will actually start creating a very elaborate and nice project. I'll see you then. Thank you for watching. 55. 6. Operations on Mutable Sequences plus Appending to a List: Okay, time to start doing operations on mutable sequences and also learn how to append lists, even though we've already appended lists, but never at this scale. This is also going to be the start of a project that we are going to do over maybe four or five videos. So let's go ahead and start the journey. First of all, I'm going to go into file and create a new Python file that's going to be called Creating car, or building underscore car. There we go. First of all, I'm going to create the current underscore choice. I'm going to say that the current choice is just equal to a. Then I'm going to say that car underscore parts is equal to an empty list. This is going to be just to create an empty list that we will fill later on. What is it nagging me about? I think it just needs an extra line. Yeah, there we go. Python doesn't like you ending at the end. It always likes to have one extra empty line of space. Don't ask me why. Then we're going to create a while loop in here. And we are going to be doing the loop while the current choice is different than zero. And by the way, this is why we set the current choice to be a. Because if we set it to be a non, this will cause an error because you cannot compare non zero, you need to have some kind of value again, we will check if the current choice is different than zero, then we're going to check the current choice is in 12345. If the current choice is in this string that we have in here, we are going to do the following. We are going to print out adding replacement field format and the current choice. Then in here I'm going to say else print, Please add option or please add an option. Please add an option from the list below. And I'm going to print out the following. I'm going to print out 12 dots or column wheels, Boom. To lights duplicate, front wings duplicate. Oh no, seats, duplicate windows finish. And then we'll have 345 and the Almighty zero. Then I'm going to say current choice is equal to the input. Your choice here. All right. So once you are done with this code, I recommend that you look through it very carefully to properly understand what is going on. Go through it line by line so that you can clearly see what is going. Because I'm going to be explaining this to you. First of all, I want you to mind the indentation. So the current choice, we are always getting an input inside of this while loop in here. Once we get that input, we are checking if the current choice is in 1234 or five. If it is, let's say the person chooses 11 will be inside or in this current string that we have in here. If it is, we are going to print out adding one or adding two or adding whatever. But if the user presses a number like eight, let's say, or 510, for example, we're going to go into the else and we're going to indicate to the user of our program that no, please choose from the options that we've given to you. Don't go wild in here. And then regardless of what he picks, unless he picks zero, of course. Because remember, while the current choice is different than zero, we keep going through this loop. If the person chooses five, or four, or ten, or 11, or one, or 19, or 500,000 we are going to ask for a current choice again. If you're still not sure how this works. Again, I recommend going line by line, understanding properly what is going. I will right click and I will run, and I will move this to the side. What happened in here? First of all, we have the current choice as a dash. We checked the condition in here. It turned out to be true, which means we go in here, We checked if the current choice is in 12345. No, it wasn't. So we went into the Ls and we printed out everything in here. Boom, there we go. Once we finished with the printing, we jumped out of the Ls and we had the current choice. Because remember, the current choice is not part of the block of code of our Ls. We're here on the current choice. Let's say I pick eight. What do you think the output will be? Think about it before you actually hit Enter. There we go, because eight is not in 12345. We printed out the Ls in here and we got all of these options. Now I'm going to pick one of these options. I will hit one. Boom. There we go. It says adding one, because one is part of the 12345, then 2345. If I hit zero, there you go. You can see that the program is terminated. Again, I recommend you test it out, you play around, You understand exactly how this works. Now we want to start actually adding these numbers into our car parts. After we say that we're adding something, we're going to do the following. We're going to check if the current choice is equal to one. We're going to call up the car parts pend and we're going to add wheels. How about that? But if it's not one, we're going to check LF, current choice is equal to two, then car parts a pend, It's going to be lights. I will hit Enter and I will duplicate this, 345. I'm going to have 34.5 I will add front wings, seats, and windows. What is happening in here? Obviously, if you haven't finished the code, pause the video, finish the code, and come back so you can clearly understand what's happening in here. What we have is we're checking if the current choice is equal to one, then we are going to be adding wheels. If the current choice is equal to two, we'll be adding lights. If the current choice is equal to three, we'll add the front wing to the car parts. We're appending the car parts just like we were appending the list of where is it? Right here, just like we were appending list B with bananas or like we were appending the shopping list with the cookies. Now, obviously we could have used the plus equals as well, but using the dot append is more sophisticated. Shall we call it that? We are doing the exact same thing in here. I'm going to remove the empty lines that we have around. Now that you've understood everything, I will add an extra space. And once we jump out of our Y loop, I'm going to print out the car parts that we have. Actually, let's just add a space in here. If I write, click and I run, I want to add Wheels. It tells me adding 123,335.0 Before I press zero and before you do it on your side, please think of what the output will be. Always do that, never just hit Enter and try to analyze. Think before you actually press Enter, think of what the output should look like and there we go. Let's look carefully at it in here. As you can see, we pressed one, which was wheels. We pressed two, which was lights. We pressed 33 times, so we got three front wings, you can never have enough front wings. And then finally we pressed five, so we got windows at the end. As you can see, we are building our car by adding one component at a time. So I recommend that you test out this entire code, make sure that everything works as you expect it to work, Add all of the car parts and whatnot, and make sure that you understand how the sequence of events and the outputs looks like. Because once you have all of that, I'm going to issue you a challenge. Your challenge is going to be to add an item, so add the stereo as an option or as one of the items that we can get with our car. And make sure to look for all the places where we need to make the modifications. Test it out. Make sure you can add that item as well. Very important to test it out past the video right now and go to the challenge. Okay, let's go ahead and get started with the challenge. You might have done it and you might have found why this is so cumbersome. First thing we need to do is we need to add it as an option. I'm going to add a six, I'm going to add stereo Next, we need to actually be able to append it to our list in here. I'm going to add an extra line and we'll duplicate this. There we go, because I'm lazy, I will make this six. This will be a stereo. There we go. Now if I write click and I run look at that. I get the option to add a stereo. But if I hit six and I hit Enter, Interesting, it doesn't tell me that we're adding a six, even though I have it in here. If I try to just finish, I still have an empty list. What gives? Well, there is one more place that I need to add a six, which is right here, so that this condition can actually trigger. Now I right click and I run and I try to hit six and another six, and maybe another front wing. Why not hit zero? And there we go. You can see that I got a stereo. You might be thinking, well, that wasn't that bad. I mean, we just added a few lines of code, A few words here and there, no problem. Well, what if somebody comes along and tells you, you know what, This car needs? A few more parts. So they hand you 500 parts that you need to add. Imagine that for a second. Imagine having to add 500 more parts. First of all, to display them in here, so that's 500 more prints that you need to add, 500 more L ifs that you need to add. And this is not even possible. You need to go up to 500 numbers, so you have to account for 678-60-7080, 125, 350, whatever. So a huge, huge blunder here. That is a problem that we will fix next, next time in a few seconds, when you watch the video, which is called iterating over lists. So, I will see you then. 56. 7. Iterating Over a List: Okay, now it's time to start optimizing our code using lists. The first thing that we need to do is we need to type in the following code at the top. In here I'm going to add two spaces and I'm going to create a list of the available parts. It will be equal to the following. We are going to have the wheels control D, to duplicate the lights control D. Front wings control D. Seats control D. Windows control D. There, there we go. Now we have the list of the available parts. The next thing we need to do is we need to use this list in order to print out the following lines. I'm actually going to comment them out because you are going to have the challenge of doing that yourself. Print out our available parts. Create a four loop over the available parts we have. Use it under the else. Print out the index of the part and the name of that part next to it. You will need to use the index that we learned about in the common operations. I don't know how fast you're going through the scores a few videos ago. It should look identical to when we hard coded in the previous lesson. Meaning it should look like 12 dots wheels, the same. We should have the same output as in here. And finally, I will give you a hint. If you don't want to look at the hint, I recommend that you pause the video right now and go to the Challenge 321 used index. Oh, well, yeah. Sometimes, I don't remember exactly what the challenges entail, but there we go. That was your hint, You already had it. If you pause the video, went and did the challenge and came back and turned out the hint was something you already knew you pretty disappointed. But anyways, pause the video right now and go to the challenge. Okay, welcome back. How did you get on with that? I hope you at least tried your best. The first thing we want to do is we want to create this fore loop that goes over all of our available parts. I'm going to say four part in available part, two dots and there we go. Now we go over all of our available parts one by one. Next I'm going to print out the following. I'm going to open up my replacement field in here, and this is the new way of using the dot format. I'm going to put in here the available parts. Do index and notes. When I hit the tab, it autocompleted and added this small behind it. I believe we've already talked about that. But because I'm recording Sam cut that out. We can see that the F was added automatically. We've already talked about that. I'm using the dot index on my available parts and I'm looking for the part. Then I also need to add a plus one in here. Mm hmm. Why do you think I added a plus one? That will be a small challenge for you to figure out before we finish up when I hit the part in here, because I want to print out the part when I right click and I run look at that, I get the same exact input. So let's talk about why we have a plus one in here. Well, if we don't have that plus one in here and we right click and we look at the output that we get, we get zero wheels, one lights. The dot index gives you the index of the first occurrence of the item that you're looking for when you type in part. For example, part when we're at the first part which is the wheels. Uh huh. Look at that. We get wheels, its index zero. Good lights. It's index is one, front wing index is two. That's correct. But as the user, as me for example, I'm using this program, I'll come in here and be like, oh, nice look at that. I want to add some wheels, hit zero, hit enter. And I'm like, what, what's that? What kind of sorcery is this? I'm trying to add wheels and you just throw me out of my own program. Yeah, not a good way to impress your boss. So we need to add a plus one in here so that it adds one to the index, and now the user can actually press on one and it tells him it's adding a one. Hit zero. There we go, we get the wheels. That was the challenge. Now we can easily and seamlessly add an extra item in here. Let's say I wanted to have a DVD player. I just type it in right there at the top when I right click and run. Look at that. Now we have a DVD player. I can add whatever more parts I want. I'm not going to add them right now because this code isn't done. Now, if I press seven, I hit Enter. Yep, it still doesn't work. I have to add it in here next to the current choices, and I also need to accommodate for it with an Lip statement. But we have started optimizing our code. Next time we're going to learn about enumerating over a list. And we'll see how that is going to help us with reducing this entire block of code in here. And this one as well. I will see you in the next video where we will learn about enumerate in functions. See you then. 57. 8. The enumerate Function: Welcome back my fellow Python programmers. In this video, we are going to be learning about the enumerate. And we'll also be using the enumerate to upgrade our project. So let's go ahead and get started. First of all, we need to understand what the enumerate is all about. First of all, the enumerate function in Python converts a data collection object into an enumerate object. Let's delve a little bit deeper. Some concepts will be confusing at first, but don't worry. We will have examples and that will allow us to understand everything. It returns an object that contains a counter as a key for each value within the object. When you enumerate over a list or any sequence for that matter, or in this situation we call it any itteruble. Which means we can iterate over it, like when we do with the four loop. We iterate over a string, or we iterate over a list. When you put ble into the enumerate, it returns two things. It returns the key and it returns a value associated with that key. What do all of these things mean? This also makes it easier to manipulate our data collections where such things are possible. For example, I can enumerate over my available parts, which returns the part and an associated number with it. That associated number will be the index. But I still call it an associated number or an associated key. Because if you enumerate over something that's not a typical list or a string or a topple, you will get something other than just the index. And we'll see what I mean by that later on when we learn about dictionaries and sets. In our current situation, we will always have the key being the index. You can even take it as a rule. But keep in mind that the key will not always be the index. Without any further ado, let's see a few examples to clearly understand what all of this is. You can then come back to the slide and re, read the theory part of the enumerate. Trust me, it's a very easy concept that's not as complicated as you can see in here. If you go back into our code in here, what we want to do is we want to enumerate over our parts right here. As you can see, when we create a for loop, we go over our available parts, that's why it's called an itterble. A list is itteruble because we can't get it iterate over it. We're going to do the same, but this time using the enumerate. First of all, I'm going to comment these lines out, now I'm going to delete the prints, but I recommend that you keep them or you copy the code and put it either below or in a new Python file. Because then you can see the progression of our program. In my case, I'm going to delete them. I recommend that you don't tell J crashed. Okay, we're back after a small crash. I commented these lines out in here. I'm going to create the following for loop. I'm going to say four number part in enumerate available parts. Notice I have two items in here instead of just one in the part. I'm saying number and part to be even more precise and in parallel with the theory that we learned, we can even call this the key. Now that I have this, I'm going to print out the following. I'm open up the a replacement field in here. Inside I'm going to type in number our key because I changed it to key, type in key and hit Tab so that the gets autocompleted. Right here on the left hand side key, two dots open up the second replacement field and the part. Let's see what the output is going to look like when I write click and I run. Look at that. As you can see we have the key which are keys are the index. And again this is only in this situation when we're using lists. Now again, let me reiterate this. About 80% of the time the key will be the index, but in certain situations it will not be. That's why I'm emphasizing this as much as possible. We have the key in here, the numbers associated with the parts. Now you can begin to understand what a A counter is you have a key for each value within an object. Where is it object into an enumerate object. The enumerate object has two parts in it. It has the key and has the actual part which is part of the available parts that we have, that is the key part pairing. Now you'll notice that in here, wheels start at zero. Obviously, we don't want that very simply. We can simply add a plus one. Run this ball. There we go. I hope you understood how this works. I will remove the following two lines. Again, I recommend that you keep them so we can see the progression of our program. But now we have a very clean fore loop that prints out all of our available parts. I hope you understood how the enumerate works because you have a challenge. Your challenge is going to be to enumerate the alphabet. You'll need to create a new Python file and call it the alphabet enumeration, Or obviously, whatever you want inside enumerate over a string, that is the alphabet, a string, not a list of strings. You will have a string which is the alphabet ABCDEFG, whatever that will be the alphabet. And you need to enumerate over that string and print out each value with its associated number. Pause the video right now and go do the challenge. Okay, there we go. In here I'm going to say four index character in enumerate and I'm going to send in the alphabet A, B, C, D, E, F, G, H I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y and Z. Yeah, there we go, That is correct Inside, I'm simply going to print out the index, the character. Notice that in here I called the key index. I will refer to it as the index going forward. But again, you have to know that it's not always the index. But in any case, if you want, you can start using it as an index from now on as, but later on you'll see that that is not always true. But anyways, when I write, click and run, there we go. You can see that we start at 0123, 43d, Nice. 56, et cetera, et cetera, until we get to 25 Z. I hope you enjoyed. I hope you understood the importance of using the enumerate. And I'll see you in the next video where we actually use this new found power to improve our code even more. I hope you enjoyed. See you in a few seconds. 58. 9. Improving our Code: Welcome back my fellow Python programmers to another video where we will be improving our code back in the building car. And here as you can see, we've already made some adjustments where instead of going through a hand manually printing out every single available car part, we now do it very easily using a for loop. This had many benefits. The first benefit was that it made our code shorter. The second benefit was it made it more dynamic. Meaning that or when we add more available parts, they automatically get displayed. It also made our code easier to debug and easier to find issues in. Now we need to improve this even further. There was an issue with this program. Some of you might have found it, but some of you might have not. The issue is on the following line number 15, where we check if the current choice is in 123456. What is the problem? It's working fine in here. If I type in three, there we go, I'm adding three. If I type in, for example, eight, there we go. You can see that it's not there. Now one of the issues is obviously that if we add, for example, a DVD player on key number seven, not registered, but that is only part of the problem. This is a small problem that we can easily solve by adding a seven right here at the top. The other problem, and the much more drastic issue in here is that if you type in 12 and hit Enter, it actually says adding 12. Oh my God. If I type in 23, it also says it's adding 23. Now if I type in 20, there we go. You can see that it tells us, please add an option from the list below. So what is the problem? Take a little bit of time to understand. So for example, if I type in 123, it also is adding 123. So look at the code, look at the condition, What is the issue in here? Okay? So if we look closely, we'll see that we're checking if the current choice is in 1234. Now this is an entire string of its own. It means that we check if the current choice, for example, 123 is in 123456. So for example, if I type in 456, it also tells me adding 456, if I type in 4536, there we go. Because the five of what? 4536 is not in 123456. So that is a big, big issue. That is the first thing that we need to handle. So what we're going to do is, or we're going to create a list of all of the valid choices right here before we actually start going through the Wi loop and getting the current choice and whatnot. We're going to do the following. We're going to create a list of our valid choices. We're going to say that for I in range, with the range being one on the length of the available parts plus one. We're going to get valid choices, append with an STR of and print out the valid choices, weird, weird code. What is this all about? First of all, I want you to take a few seconds past the video and try to understand what this code does. I do recommend that you do it. And then after that, I recommend that you add a break point so that you can try and go through this code again so you can see, all right, what's happening after you do that, try to make another prediction of what it's going to look like. Finally, we will run the code. Take a few minutes. Okay, welcome back. For me, nothing has changed. I hope you tried this mini mini challenge. When I run this program, you'll see that this is the output that I get, 123,456.7 And you'll see that each one of these are individual items inside of a list of the valid choices. As you can see, there's no complete one single string of 1234 all next to each other. Now we have a clear list of the available choices. Let's look at the code and what it actually does. First of all, created an empty string, an empty list. Nothing much in here. Then we created this fore loop. Now we have the I being the variable that is going to be increasing. Nothing too special in here. Then the special thing is the range that we have. The range is going to go from one throughout the length of the available parts plus one. And then at every single point in that range, we're going to get valid choices and append it with, but it's going to be converted into a string. Why are we, first of all, let's think of the length that we have in here, or actually the entire range. Let's consider the entire range and what's happening. Our goal is to have all of the following numbers match the parts that we have right here, as you can see. In this case they do, they go one through seven in my range. What I'm trying to do is I'm trying to associate one with wheels and the last number which is the DVD player with seven, this should be 123,456.7 That is why I start at a range of one. Makes sense, right? Because I want to start with a one. Not a zero but a one. But what that means is that if I want to go to the end to the DVD player, not only do I have to go through the length, because remember if we do length, it will return seven. If I print out the length of the available parts, I get seven. Now you might be saying, okay, so why not just use seven in here? Well, young grasshopper, you cannot use seven because in ranges it's up two. But let me hear you say it again. Up two but not including that is why we have to add a plus one right here at the end to accommodate the last element. Because if I remove this plus one and I write Click and I run, look at that, I only get to six because it gets to seven, but it's not included. I have to add a plus one. I'm going to remove this line of code. This was just for debugging purposes. If you want, you can simply comment it out, put it in another file to clearly understand. I hope that was clear. The last thing that we need to understand is why we're converting it into a string. In here we are converting this because remember in range is an integer, we want to convert it into a string because the current choice that we get in here, obviously, these valid choices will be used somewhere. It's going to be a challenge for you, but it will be used somewhere in here to check if the current choice, I gave it out. But okay, it is in the valid choices. And remember, when we're getting an input for the current choice, it is a string, that's why we convert it into a string. I hope that was understood. I hope there was no ambiguity. If you have any questions, leave them wherever that's possible. That out of the way, it's time for a bit of a challenge. Your challenge is going to be to print out the choices in the while loop. Check if the current choice is in the valid choices, then print out that we actually added that choice. Use the current choice input as an index to get the chosen part from the available parts, Append our car parts, and test it out on the last part and see if it works. This is a tough challenge. I think it's one of the harder challenges because there are a lot of things to do in here, a lot of things to think about. It's not an easy, but you'll have to use the current choice as an index to get the chosen part from the available parts. There's no hints in here, it's not an easy thing, but read carefully, read it, slowly, dissect it, and understand. Because the current choice will be used as an index, which means it has to have something happen with it. After it's used as an index, you can get the chosen part from the available parts. And once that happens, you can append your car parts. And the most important thing is you need to test it on the last part because there's a small trick in here. Past the video right now and give it your best shot. Okay. So how did you get on with that? Please, If you were able to do the challenge, post it somewhere wherever you can. Maybe in the question section or wherever you can. Posted there, posted on social media tag me, I don't care. It's a great achievement if you were able to do this challenge on your own, I congratulate you. You are becoming a great Python programmer. If not not a problem. As long as you did your best, that is the most important thing, because if you try it, you will encounter a lot of problems. And once you encounter all of those problems, you will see the solution much more clearly. Because the first thing that we need to do is we need to remove this part and say that the current choice is in the valid choices. Now if I write Click and I run, If I type in 12, look at that, it no longer works because my valid choices are one through 7123, et cetera, until seven and then eight. It does not work. One to three, no longer works. 45 no longer 56 no longer works. We only work with the valid choices that we have in here, which is amazing. That's the first part. That was the easy part of the challenge. The other part is to use the current choice input as an index to get the chosen parts from the available parts in the whole premise is to comment these lines out and replace them with a much simpler code. Now, if you weren't sure at any point, if you find yourself, oh, that was the key that I needed to finish this challenge, then pause the video again. No problem. Try to do the challenge again. No problems in there. In here, as you can see, we're saying that we're adding the current choice or whatever, adding that choice. Now we need to use the index. We need to use the current choice as an index to the chosen part. First of all, we need to have the index. The index you might be thinking should be just equal to the current choice. But the issue in here is that the current choice is a string, the index has to be an integer we converted into an integer. Great. Then we're going to get the chosen underscore part. I'm going to say that the chosen part is equal to the available parts at the index. There we go. Pretty simple. We get the current choice, let's say it's four seats, we convert it into an integer, we send it into the available parts, and we get the chosen part. But that's not all because we also have to append our car parts with the chosen part, and that was the challenge. It's still not over. There is a small hiccup in here I haven't talked about, but let's say this is what we got to because there's a small detail in here that can easily go unnoticed. Notice that one of the last points in the challenge was to test on the last part. Test it out on the last part. Let's go back in here. If I write Click and I run your choice. Let's say two for the lights, three for the front wings. Let's add three front wings. You can never have enough front wings. Let's do seven. The last part, what is that list? Index out of range. Hmm, that's weird. Let me try this again without the last part. Let's try lights and three front wings and hit zero to finish. What didn't I just order a light and three front wings? I did, but the problem was that my current choice was two When I convert two into into an integer and I put it as the index and I use it on the available parts. What is two in the available parts? It's not lights because we start at 012. Instead of having lights, I get front wing. And instead of instead of three front wings, I got three seats. And that is why it's very important to always test out your code. Even if you think that you've done everything correctly. Even if you might not have any immediate errors. It's important to test out all of the limits in your code. So how do we solve this problem? Take a few seconds to think about it. Yes, exactly. In here we do a minus one on the index. Now whatever we press, we will remove one from it and then it will be used to look through the available parts. I right click, run now, what do you want to add? Six, boom. Adding 63. Boom. Adding 33. Or four front wings. It zero. I got a stereo. And four front wings. We haven't tested out the DVD player 77750. There you go, ladies and gentlemen. We now have a very nice code. Look at how many lines of code we were able to save using our new found knowledge. There we go. Now there are still a few improvements to be made. We will definitely be coming back to this project to improve it even more. But for now, I hope you enjoyed. I know this was a long video, but I think it was full of very, very useful information. I recommend that you go through it again, Understand exactly what is happening in these three to four lines of code. And in the next video, we are going to be learning how to remove items from a list. So I hope you enjoyed and I'll see you in a few. 59. 10. Removing Items from a List: Welcome back my fellow Python programmers. In this video, we are going to be learning how we can remove instead of add items to our list. Now, how or what will be the context of our removal of items were well in our program, in here, as you can see, when we add seven, it tells us that it's adding seven. When we add another seven, it adds another seven. So what we're going to do is just simply when somebody adds seven and then removes seven or I mean, if they press seven and then press seven again, instead of adding two DVD players, we're going to be removing the DVD player. I know it's not the most fancy program ever. I'm going to give you a small homework that you can maybe do on the side to improve the program later on. But for now we just want to implement removing items from a list. So let's go ahead and get started to start off. First of all, right, here, after I get my chosen part, I check if chosen part is in the car parts. If it is, I'm going to get my car parts remove chosen part and that is it. L car parts append the chosen part. I could have actually moved this line, but it's okay. I'm just going to remove it. There we go. Now we can test it out and see if we're actually removing items. I'm going to right click and I'm going to run now the chosen part, let's say it's 123, and then I hit two again. Now if I hit zero, there we go. You can see that we first of all added wheels, great. We added lights, great. We added a front wing, great. But then we press two again, which removed or removed the lights, which means that we only have wheels and the front wing. But you can clearly see that there is an issue where it says we are adding 22 problems with this. First of all, we're saying that we're adding two even though we're moving to. The other problem is we're saying that we're adding two. We should be saying we're adding the chosen part. We're adding seats, we're adding front wings, we're adding wheels. So we want to actually print out what we're adding. And that's going to be a challenge for you. Your challenge is going to be to print out removing, adjust the code so that we print out removing. When we're removing an item, this should be sorry. And adding when we're adding an item with the item that we removed, of course with the actual name. Pass the video right now and go to the challenge. Okay, welcome back. So, how did you get on with that? It shouldn't be that hard of a challenge. I'm going to remove the print from here. Instead I'm going to print something else in here. This is where we are removing. I'm going to print out, open up the replacement field with the chosen part. I will duplicate this, hold down control shift and slide it down. And then I'll say adding, okay. Now as a rule of thumb, this is not very important right now, but it will be important when we start creating databases. It's better to actually print out after we've appended or removed items from a list or a database. It's more important than databases because let's say this line of code does not work and it errors out or it breaks or whatever happens. We don't want the user to see that we've actually removed the part. So it's better for the program to break on this line of code, not add the chosen part, and not have not having the program print out that we've removed the part. So the user like, oh great, we've removed the part but in actuality it didn't work. So it's better to print out that we've removed or added something after it was actually added. Just a small extra hint of knowledge in there for you. But that out of the way, we right click and we run your choice. 1233210, Boom. As you can see, adding wheels, adding lights, adding front wing, and then removing front wing. Removing lights, removing wheels, and all that we're left with is an empty list. So I hope you enjoy it, I hope you understood how from lists work. We're going to delve a bit deeper into removing from lists because it might not be as easy as you'd think. This is very simple concept, sometimes it's much harder removing items from a list. Now, as I told you, a small extra homework that you can do on your own, it's a very simple one. Instead of just removing an item if it's in the car parts. A good rule of thumb would be, or a good program practice would be to actually ask the user the question, would you like to remove this part or would you like to add more of this part? If the chosen part is already in our car parts, you could, for example say that, hey, would you like to add this? You already have this chosen part in your car parts. Would you like to add more or would you like to remove it? This will be a challenge for you. It's pretty simple. I think you can figure it out. There will be no solutions for this. But I do recommend that you always try to dabble and improve the code, Copy it, paste it somewhere else, the good version, and then try to change up. So I hope you enjoy it, I hope you understood everything. And I will see you in the next video where we will be talking about sorting lists. So very exciting stuff. 60. 11. Sorting Lists: Welcome back my fellow Python programmers. In this video, we are going to start learning how we can sort lists without any further ado. Let's go ahead and get started. First thing we'll do as we always do, we're going to create a new Python file and we'll call it underscore lists. There we go. So first thing we do is we have random num one. And it's equal to 124,269.81 I will then duplicate this line and I will have random number two where I'm going to have the following numbers, 314, 2,067.92, Now that we have those two random numbers lists, and keep in mind these are integers, what I'm going to do is I'm going to combine them together to make one big list. To do that, I'm going to have random number one extend random number two. Now if I print out random number one, think for a second what the output would be like or will look like when I write click and I run. This is what I get. As you can see we have list number one which ends at 81 and then list number two starts after it. We've basically extended random number one list with random number two. But as you can see, all of the numbers are still scrambled. What we want to do is we want to sort them out. So in here I'm going to do the following. I'm going to do random number one sort, I'm going to print out random number one. If I write Click and I run, there we go, Look at that. Now instead of the numbers being all scrambled around, they are sorted from the smallest to the highest. If we hover over the sort, we should see that we get the documentation. I recommend that you do this for every single new function or method, or anything that we use. You can also go to Python.org If you click on this, it will actually take you to the website where we have the sort, you can understand the keys. You can, for example, using the reverse, something that we will use in just a bit, you can read up on how all of those things work. This method sorts the list in place. As you can see, it actually sorts out the list, random number one. So let's try to use the reverse. As you can see, this is called a keyword. We will delve deeper into keywords later on. We will be using keywords from time to time, but we will not really delve into them until later on in the course. But for now, we can set reverse to be true. Now, instead of sorting them from the smallest to the biggest, we will sort them from the biggest to the smallest. That's basically how the sort works. Keep in mind that this does not create a copy of a list. It simply rearranges the items in the list that we already have. This could be very useful and lifesaving, okay? Not to that extent, but very useful when you have a list that could be several gigabytes. So imagine if you have a list that's several gigabytes and you have to create an entirely new one that is sorted. It's going to take you some time. This is a much more efficient way. I hope you understood there's nothing too much in here. Again, I do recommend that you go through the documentation, but for now I have a challenge for you. Your challenge is going to get another number. You'll need to create another numb and set it as the random number four. Before it is sorted you'll need to print it out as well. And then print it out after we've sorted random number one, is there any changes? And what does that mean again, another number. It should create another number, variable it before random number one is sorted right here. Then I want you to print out another number again and tell me what the output looks like. Pass the video right now and go to the challenge. Okay, welcome back. How did you get on with that? So the first thing that I'm going to do is I'm going to set random number one. I think we can set it right here, another number to random number one. Underscore numb will be equal to random number one. I'm also going to print out another number. When I write click and I run, we should see that we have another number which is equal to the random number one. Not too many things to talk about here. Now I will add a print just so we can distinguish between the two lines. And I'm going to print out another number Again, I hope you always think of what the output is going to be like before you actually run. Let's see what's going to happen here. When I right click and look at that number was also sorted. Oh, my magic, isn't it? Well, if you've been following the past a few lessons, you will know that lists are mutable. Another list or another number points to random number one when random number one was sorted. Because it is mutable, it means that the object actually changes, which means that everything pointing to that object also changed, which means another number also was sorted. So I hope you enjoyed, I hope you understood how this works and why another number was also sorted. In the next video, we are going to look at sorting things, meaning that instead of sorting a list, we're going to just be sorting things that are inside of it. I'll see you in a few seconds. 61. 12. Sorting Things: Welcome back my fellow Python programmers to a brand new video. And in this one we are going to start learning how we can be sorting things as always. First thing we do is we go into file, create a new Python file and call it underscore things. Now I'm going to create a message that a lot of Hobbits are familiar with. It's going to be, one does not simply walk into mordor. There we go. If you didn't understand that mean or that sentence, then congratulations, You've probably had much more social encounters that I have. But anyways, what I'm going to do now is I'm going to say that letters is equal to sorted. And I'm going to send the message as a parameter, and then I'm going to print out letters. Notice again, just came to my mind, we always keep an empty space below in here. If I write click, I run, look at what I get. Let me just log this right here. Look at what I get. I get some weird stuff in here. Weird, okay. But then I have M cool and then I have A D, D, E, E, I, I, K, L, L, M, N Op. All right. There we go. I'm not going to say every single letter, but as you can see, there are a few things in here. First of all, the most important thing that you need to know about what happened here is that we've created a list. You can understand that this is a list because of the square brackets that are around this collection of items. Next inside, we have each individual character that was in the message sorted out from the smallest to the biggest. The spaces are considered the smallest. Then we have the upper case letters. Only then afterwards do we have the lower case letters, the sorted. What does it do? If we hover over it again, you'll see that it returns a new list containing all the items from the interbal in ascending order. Again, we can always open the documentation in here as well. You can see it also has its own reverse key. You can go and see how it works. Again, I recommend that you spend a little bit of time in the Python documentation and get acquainted with it. You will definitely see it in the future. If this is the career path that you are going down to, as you can see, sort creates a list and sets everything in ascending order. But it doesn't need to only be on a specific message, It can also be on a list of numbers. If we have a list of numbers, and we have 2.34 0.58 0.73 0.19 point 2.1 0.6 Here I'm going to say that underscore numbers is equal to numbers If I print out sort numbers and if I print out numbers, now you might be thinking, why are we printing out numbers? Again, this will be important in just a bit because if I write the click and I run the first thing, I notice that the sorted number that I printed out is that number was a list. And we used sorted on the numbers and sort numbers is still a list that we have, number not sorted out. And it's important to realize this. Why? Because in the previous lesson where we had sorting lists and we used the sort, notice that another number actually changed. It was actually sorted, but when we're using the sorted method, here we are setting it in a new variable. We're creating a new list. And we're setting it there. Numbers in itself is not being sorted. We are sorting numbers. And we're setting it, or putting it into the sorted numbers variable, we're creating a completely new list. And this is a very central point and that's the main difference between the dot sort and the sorted. For example, if I do the following, if I do numbers sort, what do you think the output is going to be of the last line? When I write click and I run. Look at that, you'll see that numbers was also sorted. That is the main difference. Sorted actually creates a new list and leaves the original one untacked. It assigns it to a new variable, or to be more specific, we assign it to a new variable, and that is the main difference. A new copy is created with the sorted. I hope you understood, I hope it wasn't too complicated. Now what I'm going to do is I'm going to give you a bit of a challenge. Your challenge is going to be to do the wrong thing. You need to create a variable and set it as number sorted. Create a variable, pretty simple, and say that it's equal to number sort, print out the numbers, print out the actual numbers, and print out the variable that we created at 0.1 Pass the video right now and go do the challenge. Okay, How did you get on with that pretty simple challenge? Nothing too much in here. I'm simply going to say another numbers is equal to numbers. Sort look, even before we try to do anything, I'm also going to say that I want to print out another number even before we try to do anything or run the program. We immediately have a small warning in here. Now, sometimes these warnings can cause errors or cause a problem with the project or program, but sometimes they don't. In this case, they won't cause any problem. But there is going to be some weird unexpected output which is just none. If we hover over this error, it will tell us that function sort doesn't return anything that is true. And sorting in here, sorting lists, if we hover over the sort, it sorts the list in ascending order and returns none. And when we say returns none, it means we don't return anything. We will delve deeper into functions that return functions that don't return, what's none, et cetera, later on. But for now we need to know that sort doesn't return anything because it actually sorts out the list it's being used on. So that is the gist of it. We cannot set another sorted number equal to numbers sort because just doesn't return anything. It just sorts out the list and that's it. All right, before leaving, I want to show you something really cool. We're going to create the missing underscore letters. And I'll say that it's equal to sorted. And inside I will type in the following, the quick brown fox jumps over. Lazy I will print out the missing letters. I'll also just have a print in here. If I read Click and I run, look at what I get. I get the empty spaces being set at the beginning, pretty typical. Then I'm going to have A, B, C, D, E, F G H I J K L M and O P Q R S T U V W X Y N Z. So what have you noticed about the output that we got? Well, what you should notice is that we have all of the letters in the alphabet, and the quick brown fox jumps over. The lazy dog is a sentence that is called a pangram sentence. Which means it contains all the letters from the alphabet at least once before we move on. I know I've said it before, but one small little thing in here that we also need to keep in mind is that if we call our variable just sorted, regardless of this error in here we have a warning which is called shadows built in name sorted, whatever. This is something in Python that you need to know. It's not very friendly to create variables with names of things or functions that are built in in Python. Meaning we already have a function called sorted, so you wouldn't really want to create a function. Later on we'll learn how to create functions. You wouldn't want to create a function, you wouldn't want to create a variable that is called sorted. It calls shadow built in name sorted. Just a small lesson for the future ladies and gentlemen. I hope you enjoy it. I hope you're having fun. In the next video, we are going to learn how we can do case sensitive sorting. Because notice in here, the T is not in its correct place. It should be next to this right here. So we're going to learn how we can do this without any case sensitivity. Thanks so much for watching. I hope you enjoy it, and I'll see you in a few seconds. 62. 13. Case-Insensitive Sorting: Welcome back my fellow Python programmers to another video. In this one, we are going to be creating case sensitive sorting. Let's go ahead and get started. First thing I'm going to do is I'm going to make sure that when I sort out the letters in here, that I have the T in the proper position. It's very simple to do that simply in here. On the sorted function, I will add a, and I'm going to add a keyword which is key equal str case fold. But keep in mind that in here, look, we immediately have an error or a warning, unexpected type SDR SDR. The thing that you need to know in here is that you need to remove the parentheses. Why are we removing the parentheses? Well, because you've seen that case fold is actually called. It's a function that gets called. But in here we don't want to call this function, we just want to use it as it is, as a keyword. When you remove the parentheses, it means that the function is not called, which is what we want. Now if we write Click and we run, you'll see that we have all of these empty spaces. And on the, there we go, you can see that the capital gets placed before the small. It's not because of its order, I think it's just because of its order in here. Where's the capital T? Oh, yes, it's because of where the T is actually placed. The big T is the first, that's why its order is that way. The next thing that we're going to do is we are going to try and sort out a list of names. I'm going to create the list of names in here. First of all, I will add a empty print and I'm going to say that names are equal to, we'll have John, Ned Brand. Come on Robert, and hold. If you don't, you don't. These are the names that we want to sort out. I'm going to issue you a challenge to actually sort these names out, you need to The names, print out the sorted list. Now, inside of the parentheses on the send in the case key. Pass the video right now and do the challenge. Okay. Welcome back. So I'm going to get the names sort. I will print out the names when I write. Click and I run. There we go. You can see that now. Aria is in the beginning then John, Ned, Robert. But the issue in here is that brand and holdor are at the end, even though brand starts with a B, which means it should be here behind J and hold as well. For that reason, we use the key STR in here. I'm going to add key equals SDR case fold. When I write Click and I look at that. Now brand and hold are in their respective position. Using the R case fold is very helpful unless we obviously these are names. Brand should have an upper case holder, should have an upper case H, but some situations will have this problem. Sometimes when you're working with databases. This could be an issue where someone hasn't capitalized their name or you didn't create the proper methods and uses for it. So using the case fold would be helpful. It's good to know these kinds of things. So thanks so much for watching. I hope you enjoyed. And in the next video we are going to look at creating lists. You might be thinking, wait, we've been creating lists for a very long time, but we're going to delve a little bit deeper and see what's happening under the hook. So I'll see you in a few seconds. 63. 14. Creating Lists: Welcome back my fellow Python programmers to another video. And in this one we are going to be learning how we can create lists in different ways. Let's go ahead and get started. First thing I'll do is I will create a new Python file and call it creating underscore lists. Hit Enter and close this down. For now, I will create the first list which is going to be equal, which is going to be called e equal to 2468. I will duplicate this and call this odd and have 1,357.9 and add three spaces. As you can see, we have two lists of the even and odd numbers. Nothing too special in here. Next I'm going to get numbers, and I'll say that it's equal to even plus odd. Then I'm going to say that print numbers. If I write click and I run, I should get the following. As you can see, 24681357. This is the first way that we can create a list by simply concatenating or adding a plus between two different lists. Meaning we create a third one. Okay? So that is the first way of creating a list. Nothing too special. We're just going to go over a few methods of creating lists. The second way is using the sorted, because remember, when we use the sorted method, it returns a list as well. Meaning it creates a list. I'm going to call this the underscore numbers, and I'll say that it's equal to sorted. And inside we'll send in numbers and I will print out sorted numbers. Again, if we have our over the sorted method, it returns a new list containing all the items. This is another way of creating lists. When I write click and I run, this is the output that I get, a completely different and new list. Let's also test it out on a string and see what happens if we use it in here. I'm going to say that I have digits and the digits are equal to sorted inside of the sorted. I will send in 12 or actually 15 978-632-1324 I mean, these are all nine numbers. If I print out digits, what do you think the output is going to look like? Think about it for a little bit before running, okay? So if I write Click and I run, this is the output. You can see that this string was converted into a list, but it was a list of strings. Meaning that when we create a list from another object, the content of that list will be of the same pipe. For example, using the, when we created the sorted numbers out of the numbers, it was already a list of integers. The list that was created was a list of integers as well. But in here we had strings, so it was a list of strings. Okay? Now what we can also do is the following. I'm going to duplicate this and comment it out, and instead of sorted, I'm just going to use list in here. Now, this is not a method per se. It is a method, but it's also a constructor. We're going to look more into constructors when we start learning about classes. But for now, all that you need to know that you can consider this a normal method. When I write Click and I look at that, it creates a list that is not sorted, but it's still a list of strings. Because what we're trying to create a list out of our strings. Finally, to look at and make sure that the list is actually creating a different list, I'm going to say that more numbers is equal to a list of numbers, and I will print out more numbers. Let me also just have an empty print in here, more numbers. And I will print out the ID of numbers first and then more numbers. Let's see if they match. If I write Click and I run, there we go. Look at that, we have two completely different ID's. As you can see, it means that we have two completely different lists, which means that list actually creates a new list. So with all of that out of the way, this is a very simple lesson. I don't think we need more explanation than that. I'm going to issue you a bit of a challenge. And your challenge is going to be, is this the same number? So you'll need to print out the bullion value of the following two statements. Number is the same as more numbers. Numbers is equal to more numbers. Now, a lot of students get confused on what is the same and is equal. This is something for you to find out, but I'm going to give you an indication of what it means to print out the bull value because this is not something that we've specifically talked about. It means that if we want to print out the condition, so similar to how we were checking if let's say some kind of variable is equal to another variable, and we would use it in the if statement, we want to use it and put it instead inside of the print arguments in here. Post the video right now and go do the challenge. Okay, welcome back in here, I'll keep this empty print and then I will print out numbers is more numbers. This was the first part of the challenge that checks if these are actually the same object or not. When we say numbers is more numbers, we're checking if they are the same or to be more specific, we are comparing their ID's. I will duplicate this and check if they are equal two equal signs, if numbers is equal to more numbers. When I write click and I run, I can see that they are not the same because the output is false, but they are equal to each other. They are equal in terms of content, in terms of items, but they are not the same. They are two completely different lists. Before we move on, I still have a few sticky ways of creating lists. The first way is to use a slice in. Wait, let me actually comment this out. Duplicate it. And comment it out, I don't need to print, We'll just work on the more numbers. Keep the last line in here, in here. I'm going to, let me move this up, control shift to move up. Instead, I'm going to say that more numbers is equal to numbers. Open up the two square brackets and simply add a column inside. When I write, click and I run, you'll see that I create a completely new list. Do you remember what this is exactly? For some of you, this is called the slice. And when I don't present with the beginning or the end point of the slice, it just slices from the beginning until the end. When you slice, you actually create a new list. The last method that I want to show you will be the following. If we say more underscore numbers equal to numbers, copy, and this basically creates a copy. This is the easiest one, there's nothing too much to it. There we go, you write the click you run, you create more numbers, and they have completely different IDs. And you can see that they are not the same, but they are equal to each other. So these are the basic ways of creating lists. It's important to know these ways. If you ever encounter some of them, you can immediately pick on them. So thanks so much for watching. I hope you enjoyed and I will see you in the next video where we will learn how we can start replacing slices from our lists. See you in a few seconds. 64. 15. Replacing a slice: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to learn how we can start replacing slices as always. We're going to create a new Python file and we're going to call it replacing slices here. I'm going to create the following list of car underscore parts, and I'm going to say that it's equal to wheels, lights, or front wing seats. Come on Windows and stereo. There we go. Now what I will do later on is I'm going to drag the output and put it in here and make it slightly bigger. As you can see, it obscures our view of the list. Instead of writing it like this, I'm going to hit Enter to separate each one on its own line. There we go. Also something to keep in mind, and I love this about Python, is that you can add a coma at the end. Most programming languages will not allow you to do this. It will start telling you like, no, that's it, you finished the stereo. You cannot add another coma unless you have another object. But Python is very helpful. It considers you as an adult. It thinks that, all right, this guy or this Gal knows what they're doing. So they can just or not a complete freedom I, because I've spent years programming in different languages and not having the ability to add. So now that I can I always add a. Anyways, that's beside the point. Now that we have our list of car parts, I'm going to print out the car parts. If we write, click and we run, this is what we get. A list of car parts. We can see that it's a list because of the square brackets that we have on each side. Obviously it's a list of strings because of the single quotation mark that we have. Again, obviously we could have used the double quotation marks for any of these. If I write, Click and I run, you can see the output stays the same. Single quotation marks, it doesn't matter. Use whatever you want. Just like we were able to access specific characters in a string using the square brackets, we can do the same to access specific items in a list. What I mean by that is if I want to print out car parts at position number three, what do you think the output is going to be? Think about it when I write, click and I run. I get seats because wheels is at position 0,012.3 I get seats. If I try to print out four, think about it again before boom. There we go. Windows. All right. Now that we have that out of the way, I will print out cars again, normally. Now what I want to do is I want to replace one of my car parts with a different car part. Meaning that I'm going to say car part or car parts at position three is now equal to rents. And I'm going to print out the car parts. I right click and I run. Boom, there we go. You can see that now instead of the seats, I have rims. Excellent. Nothing too much here. We're simply replacing a single item. Let's continue on, and let's look at replacing an entire slice. I'm going to comment this line out and I'm going to say that car parts at position three until the end is equal to rims. If I right click and I run, look at what I get, I get wheels, lights, front wing, and then I get R I MS. So what is the problem in here? The problem is that, well, first of all, let's look at the obvious. We don't have any stereo windows or seats. If you don't remember how slicing works, I recommend that you go back to section number two. I think where we learn all about slices. But basically what we do is we go from three, from number three, which is seeds, until the end, and we replace it with whatever the output is. The issue in here is that string is a sequence, which means that Python interprets it as, let's say in between quotation marks. Kind of a list with R IS being individual items in it. So when you say car parts from three until the end is equal to rims. Now it just thinks that R is an item that we need to add, is an item that we need to add. M is an item that we need to add and is an item that we need to add four separate items, replace the three items that we had in here. This is an issue, obviously, this is not something that we want. We want to just add or replace seats, windows, and stereo with single item which is brims. But it's going to be a challenge for you. And your challenge is going to be to replace a slice. Replace an entire slice with another car component or part. Use a string, strictly a string. Same way as we did with the individual items. Print out the resulting list. Now, instead of replacing it with a string, replace it with an entire item and then check the result. Now you might be thinking, wait, wait, wait. What does it mean to have an entire item replace a specific slice? I'm going to keep this as a guess for you to think about. You can also go look for it online or something. It's going to be very fun. Try it out, do your best, and I'll see you in just a bit. Okay, welcome back. So how did you get on with that? I'm going to stick with rims. I'm not going to use another component in here. What I'm going to do to make sure that this is interpreted as an item to a list is simply add square brackets around the rims. Now this is an item that contains a or an item of type string which contains rims or is of value rims. If I write click Run, look at the output, now it's completely different. Instead of having individual characters being part or individual characters items, now we have the entire item which is rims. I hope you enjoyed, I hope you understood how this works. In the next video, we are going to learn how we can start deleting items from a list. Even though we've seen removing items from a list, we'll see that deleting is a completely different beast. I'll see you in a few seconds. 65. 16. Deleting Items from a List: Welcome back my fellow Python programmers to another video. And in this video, we are going to learn how we can start deleting items from a list. Now you might be thinking, wait, we've already removed items from a list, and this will be definitely different. Deleting items is going to have its own intricacies and we're going to see them. First things first, we need to create a new Python file that I'm going to call deleting underscore items, underscore from underscore lists. I'm going to create the inputs underscore, underscore in. And the inputs coming in are going to be 01, 234-567-8910, Wait 11, 12, 131-415-1617, There we go. So these are our inputs coming in. I take your time, write all of these out. You didn't think you would be doing math to day, right? That was bad. But anyways, now what we want to do is we want to delete some of the inputs that are coming in. So I'm going to hit delete. So then inputs I'm going to delete going 0-2 then I'm going to print out the inputs coming in. Now if I right click and I run as expected, we should see that the first three elements get, sorry, the first two items get deleted because remember when slicing the end is not included, we delete from zero until 10.1 are deleted. There we go. You can see this is our new formed list. So now I'm going to issue you a challenge. And this challenge is going to help you to see below the surface of what's happening. So your challenge is going to be to delete a slice, So similar to what we did now. So you'll need to delete everything from position 16 and up. Do this after the first deletion. Keep the current deletion that we did, which is 0-2 Keep that. And then afterwards delete everything from 16 and upwards, print out the inputs. What does the result mean? I'm pretty sure you're going to have some kind of weird result and maybe an unexpected result. Pass the video right now and go do the challenge. So how did you get on with that? Well, what I'm going to do is I'm going to select these two lines, copy them, paste them in here. And then I'm going to delete everything from 16 and up. Meaning I'm not going to provide with the end result. If I write the click and I run, huh? Interesting. I got the same exact result. Well you probably had the same thing happen to you. What does this result mean? What does it mean when we try to delete from number 16 and upwards and it's not provided to us? Well, let me show you what is happening below the surface. I try to print out the following. I'm going to create a forward Now you don't have to do this, I'm just showing you this to prove to you the point. If you want, you can write the code. I'm going to do four I in inputs coming in. I'm going to print out, or actually know what to make it even better. I'm going to have an enumerate over the inputs coming in and I'll have the in the value. I will print out index value. When I write a click and I run, there we go, you can see that I have zero at 01, at one to two until we get to 17. Pretty obvious, nothing too strange in here, but if I copy this and I put it right here, and I'm actually going to create a print inside of the print, I'll just create this multiplication symbol and multiply it by 20 so that we can have a clear difference between where the indexes are. Now if I run, look at that now because we've deleted the first two elements. Zero, or index zero has a value of two. Look at that. Index one has a value of 32435 and et cetera, et cetera. When you and I, when we tried to delete from position 16 and upwards, what happened is Python went into this inputs coming in. It looked for position 16 and it did not find anything. That is what you should start thinking about when you are deleting items from a list. The list actually shifts and changes, and empty spaces are filled with the values that are after the indexes. This is very important to understand. I recommend that you clearly look at the outputs that we got. Again, even though I said you shouldn't write the code, I do recommend that you write the code if you want. You can also go through this with AD Bugger. You can add a debugger here or anywhere you'd like and slowly go through the program to properly understand what is happening. As you can see, the list shifts, we've removed two items, two indexes were deleted, and all of the list shifted to the left. That's why when we try to delete from 16 and upwards, nothing happened. Let's see a more intricate example to understand this fully. I'm going to comment out everything in here. Never delete code, always comment the code out because you might want to get back to re, understand what happened in here. I'm going to create the in underscore valid and I'm going to say that it's equal to five and I'm going to have the max valid and I'm going to say that it's equal to 12. The minimum value that we can have will be five and the maximum valid value that we can have will be 12. I'm going to create a loop in here, four index value in enumerate inputs coming in. I'm going to check if the value is less than the minimum valid or the value is greater than the max valid. I'm going to delete the inputs coming in at the index. Finally, I will print out the inputs coming in. What is happening here? First of all, we're creating index and value. We're getting it from the enumerate. Same thing as we did in here. Same thing as we did in video number nine, if I'm not mistaken, which was called the enumerate function. You can go back to that video and rewatch it in here. We get the index, we get the value, and we value that. We're extracting the value at every single point in here. If the value that we're getting is less than the minimum valid or the value is greater than the max valid, I'm going to delete the inputs coming in at the index. So let's say we start at zero, We have index zero. Value zero we check is value less than the minimum valid it is. Then I'm going to delete the inputs coming in at index zero, which means I will delete zero. Then let's say we are at index 15 right here. Index 15. Value 15 is the value less than the max valid? No, it's not because 15 is not less than five or value is greater than the max valid. Yes, 15 is greater than 12. So we will delete the inputs coming in at the index number 15. So we delete this number. So we should have, in theory, the inputs coming in from five until 12. If we write click and re run, this is the output that we get. We have 130 and 2.4 were removed. I mean that's the start. I guess we have 1356, all the numbers are normal. Then we have 12, 14, 16, which means 1,315.17 were removed. Okay, what is happening here? Now use the information that you got from this old code and apply it to the code that we have in here. And think about what happened. If you're thinking that the list is shifting as we're deleting items, you are correct what is happening here. Now I recommend that you try on your own, adding a debugger here and going through the list to properly understand what's happening. After you've tried understanding and if you can't figure it out, amazing, congratulations. If you let me take you through the explanation. What is happening here? I need your full concentration. This is not an easy concept to wrap your head around, but once you do, you are golden. We have the inputs coming in, 0123 until 17, and we also have the indexes. Everything in red below these values is going to be the indexes. We have 0123 until six until 17. We are going to delete if it's less than five. Let's go ahead and create the four loop. You can see in here that we have at position zero, at the index on the loop zero, we have the following list. What we do is at zero, we check that we have value zero, correct? So we're going to delete zero. What happens to the list after we delete zero? This is what happens. Now the list is 123456. No one is at index 02, is at index 13, is at index two, et cetera, et cetera. The indexes don't accommodate the actual values. The indexes will always start at zero and go and increase one by one. But what does the four loop do? The four loop doesn't care what you're doing inside of the four loop. It will just add a plus one. And now we're working on index one and what's at index one? At index one we have two. We delete two, we skip the one. What happens to the list? Now we have 13.4 The loop doesn't care what we did, the loop increases by one. Now we're working on index two. What do we have on index two? We have four. We delete four, and now this is what we are left with. We are left with 1356 and this is what we got. And same thing happens on the other side. Sorry, I might have been a little bit fast. Take this in, go through this again step by step and understand what's happening. Once you do, let's move on to the other side. If you did figure out what happened on the left hand side, take the time to, again understand what happened on the right hand side, because once we get to index number ten, we have 13 at index number 1013 is greater than 12, we delete 13. What happens? All of the list shifts a little bit downwards. And by the way, the index in here ends at 14. Why it should be obvious? Because we've already removed three elements. 17 minus three equals 14, that's why 17 is at index 14. Remember we removed three elements in here. Again we remove 13. Now we have 14 at position 1015, at 11. Again, the four loop doesn't care. Plus one, we get 11. What happens? We delete 15. This is what our list now looks like, 14, 16, 17. The four loop doesn't care. We go to 12. What do we have at 12:17 We delete 17, and this is the list that we are left off. That is where we got our weird output Of the inputs coming in, we have 1,356,789.11 12, 14, 16, just like we got with our output in here. Some of you will be like, oh, this makes so much sense. Others might be looking at this and being, wow, what the hell just happened? Some of you might be okay. Maybe I need a little bit more time to understand this. All of these are valid. This is not an easy concept to wrap your head around, but it's important to understand what is happening. In the next video, we are going to learn how we can safely remove items from a list. And then we'll even learn a much better way of removing items of a roll when they're not even in a proper sequence. Because look, right now we have 0123. We know what's happening. Later on we will learn what happens when it's much harder than this. Thanks so much for watching. I hope you understood. I do recommend that you go back. Watch this again. Understand properly how the slides are working. I'm going to provide you with the slides so you will be able to go through the animations on your own and fully understand what is happening. Thank you so much. I'll see you in the next video. 66. 17. Safely removing values from a list: Welcome back to my favorite Python developers. In this video, we are going to learn how we can safely remove items from a list. As you saw, removing items from my list is a very dangerous occupation. So we need to find a way to remove these items in a more efficient and well overall, just remove them properly because we don't want to have all of the issues that we've had before. So let's go ahead and get started. First thing I'm going to do is I'm going to remove the code in here. Again, not remove, we will comment things out. We want to have the progression of what's happening. I even recommend that you start adding comments and say, this method we used, et cetera, et cetera, add some description for you to understand. We're going to keep the minimum valid and the max valid. We are going to keep using the same inputs coming in. But now we're going to start doing things a little bit differently because first of all, we're going to process the low values in the list. Let me add a space. We're going to start processing the low values. I'm going to say stop equal zero. This is a variable, I'm initializing it, I'm going to say four index value in enumerate over the inputs coming in. I'm going to check if the value is greater than or equal to the minimum valid. I'm going to set the stop to be equal to the index and I'm going to break out interesting. Then I'm going to print out the stop. This will be purely for debugging. For debugging, then I'm going to delete inputs coming in from the beginning until the stop. And I will print out the inputs coming in. So I'm going to run this, but before I do, I recommend that you go through the code. It's not very complicated. It's definitely less complicated than what we've done before. Try to understand what's happening. Obviously I'm going to explain to you what happened. And then we will continue. I'm going to write Click, and I'm going to run and look at our output. How nice is that we've deleted all the items from zero until five. What is happening in here? First of all, we initialize the stop at zero. Then we created an enumerate, we got the index and the value. And we're checking at each incrementation of the four loop, we're checking if the value is greater than or equal to the minimum valid, which is five. We're checking is it greater than or equal to five? No it's not. Then we will postpone, we will not set the stop and we will go back in the four loop. We start at zero, is greater than the minimum valid. No, it's not. The move to one, is it greater? No, we move to two, to three, to four and then we get to five. So once we got to five, we looked at it, is the value was five, is five greater than or equal to the minimum valid? Yes, it was. It was equal to. We entered into the code, we set the stop to be equal to the index. Now, stop is equal to what? Yes exactly to five. And then we broke out of our fore loop. We printed out the stop. We deleted everything from the beginning until the stop. And keep in mind the stop is not included. This was inputs coming in from the beginning or from zero until five. But five is not included. It's up to but not in, and we printed out the output. I hope you're not too confused. This is not a very complicated, it's definitely less complicated than what we've done before. If you're having a hard time again, go through it again, use the debugger. As always, it's very helpful. The important thing here is that we don't change or delete data of the list inside of a loop. Only when we finish the loop do we start changing the data. Okay, it's very important to not change the data inside of the loop. After we've done this, it's time to handle the high numbers. I'm going to add two spaces in here. I'm going to create another comment which is process the high values in the list. And I wrote high incorrectly. Very nice. I'm going to set the start equal to zero. This one will be slightly more complicated. I'm going to say four index range. The range is going to be the length of the inputs coming in minus one, minus one, minus one. And you're like, what is happening here? I'm going to check if the inputs coming in at the index is less than or equal to the max valid. And it's not allowing because it's less than or equal to, yep, sorry, the max valid. I'm going to set the start to be equal to the index and I will break out. Once I do, I will print out the start for debugging, delete inputs coming in, start until the end, and print out the inputs coming in. If I now right click and I run, this is the output that I get. As you can see, the index that start or that I start at is going to be equal to seven. And we delete everything from the start, which is seven until the end. So how did we come up with this? If we look, remember that the seven represents the index in this list that we have. The list where we've already deleted if you items. So we have five at zero, so 012345, 67a7, we start deleting and we delete everything upwards. Now you might be already thinking, wait 12 is the max valid. Of course, this is going to be an issue for you to solve later on, but before we can solve it, we need to understand what is happening in here. I'm pretty confident that you know what's happening in these three lines. There you go. If you were confused now you know. But we need to understand what's happening in these four lines. First of all, we know the break. That's good. We know the start equals index, that's good. Now, what's happening in these two lines? Inputs coming in at the index is less than the max value. We're just checking the inputs coming in at that index. Remember, the index is a variable. It's changing inputs coming in at the index. If it's less than or equal to the max valid, we'll set the start equal to the index and break out The more important and pressing thing that I think you might not be very familiar with is this range right here. This range. What is happening in this range? I'll just add a small comment in here, and I'll say we're using minus one because the last value isn't included. Actually, you know what? That's too long. I'm going to copy this. Cut this in here. What's happening? First of all, we need to understand how the range works. Just like we have the slices and the ranges, you can see right here, we have the starting point. The starting point is going to be the length of the inputs coming in minus one. Why are we doing this? Because we want to start at the last element. In this case it's 17, or to be more precise, in this case it's 17. We want to start at the end. How do we start at the end? First of all, we get the length of our entire inputs coming in. The length of the inputs coming in is going to be more or one more, than the indexes that we have. Because remember we start at 05, is at zero, the length is going to be 0123, 4567, 8910, 1112. There are 13 elements in here, It would have been easier for me to just say 17 minus 1234517, minus five is 12. We have 12 elements, the length is 12, but the index is going to end at 11. So we need to do length of the inputs minus one. And then the value that we want to get to is going to be minus one, because we want to go until the first index because we don't know where this ends. And finally we have the step which is going backwards. To better understand this, what I'm going to do is I'm going to set value underscore. We underscore our, underscore, please our at a. This is really unnecessary. I'm just going to say value equals to the inputs coming in at the index, I'll just print out the value. This is simply for debugging purposes. You don't need to do this. If you want, I will red click, I will debug. Actually step into value, print out the value. What do we get on the console? Let me drag this and put it in here, see better. All right, there we go. The first value was 17. We started at the end at 17, then we step into, again, we go back, we do minus one. Remember we're going backwards. Now we check what is the value. It's 161-514-1312 And now once it's 12, we set the start to be equal to the index, because remember what index are we at? We are at seven when we step into again, boom, we want to break out and we will print out the start, which is seven, and we will delete everything going from the start until the end. There we go again. I recommend you go through this one more time, a few more times to fully understand it and you'll even have the chance to understand it even more. I will comment these two lines out. These were purely for debugging because you have a challenge. Your challenge is going to be to not remove the start. Remember, we don't want to remove the 12, we want to keep the 12. Find a way for us not to remove the first item at the start. I will give you a hint. If you don't want the hint, go to the code and do the challenge. We need to add a plus one. We can do that in two places, find one of them. There is one place, or there are two places where we can add the plus one. We need to find one of them past the video right now and go do the challenge. Okay, welcome back. So how did you get on with that? There are two places where we can do this. Let me just close this one down. We can either add a plus one right here. Now when I write click Run, look at that. We start at 12, because remember we just add a plus one to the start. But I find it much better to put it in here. We increase the index by one. There's no real inherent difference between these two. Both of them are the same. But if you had to choose, if you had to choose, it's better to add it right here as a rule of thumb. It's not very friendly or user friendly, let's call it just not a very good programming habit of actually changing the start. It's better to change the way the start is used, if that makes sense to add the plus one here. Not change the value but how the value is used. Again, if you ever see anybody doing the plus one on the actual index, it is 100% correct. I'm just saying if you just wanted a small thing to tip the scales, this is what it would be. Ladies and gentlemen, these two lessons were very hard to understand. I know, but they are very crucial. I hope you understood. In the next video, we are going to look at removing items from a list going backwards. I'll see you in the next video. 67. 18. Removing Items from a List Backwards: Welcome back my favorite Python developers. In this video we are going to understand why iterating backwards over a list. To delete items from it is better long headline. But you'll get the point when we talk about it. When you iterate over a list forwards and delete items from it, the index of the remaining items shift down each time you delete said item. Just like we saw in the previous examples we had, whenever you delete an item in the beginning, all of the list shifts downwards. This can cause you to skip over some items or process the same item more than once. In this situation, we're deleting an item, but what if we were doing something like maybe getting passwords, maybe changing the location of passwords? This can cause a lot of trouble, a lot of confusion, and can sometimes destroy entire companies and databases. Maybe not that much. But you get the point, it's a dangerous thing to do. Iterating backwards over a list. Delete items avoids this issue. Because you are deleting items from the end of the list first, which means you don't affect the indexes of the remaining items just like we had the zero through 17. If you delete 1701234 are not going to get affected. You've just deleted from the end, the numbers in the middle and in the beginning are not affected at all. Their indexes have not changed. That's why deleting from the end is so much better. Finally, overall, iterating backwards over a list to delete items is considered a safer approach because it helps you avoid unexpected box in your code whenever you have something to do with changing the values of a list. Of course, to certain extent in this situation, it's when you're deleting. Obviously when you're changing values, it's also better to iterate backwards. Let's see one final example, just to hone down all of this information you've just seen the background into what's happening behind the scenes. I'll call it, maybe I should create a video of how all of this happens behind the scenes. Tell me if you're interested about that. Let's go ahead and create a new Python file that I'm going to call backwards and maybe just add underscore between go backwards, hit Enter, and I'm going to have a set of data that will be 104-10-1410 5, 308-103-5107 100 3 061-061-2108 These are our values. And again, I didn't want to write them on a single long line of code so that we can always see what is happening. And the reason why I chose this seemingly random set of numbers is because up until now, the numbers that we were working on were in order. I don't want them to be in an order. I want to show you how we can do this when they're not properly ordered. I'm going to have the minimum valid equal to 100. I'm going to have the max underscore valid equal to 200. And I'm going to check four index in range length of the data minus one. This is to start at the last element at one oh eight minus one. That is, so that we get to the first element minus one is the step to actually be going backwards. Then I'll check if the data at the index is less than the minimum valid or the data at the index is greater than the max valid, I will print out the index. I will delete the data at the index. I will print out the data. Keep in mind, I'm printing out the data inside of the for loop so that I can see things changing at every step of the way. One more thing, before we actually run this right here, when we were doing the following right here on this if statement. As you can see, we said value minium, valid and value or value greater than the max valid. And I used the parentheses in here, while in the go backwards I did not use parentheses. The reason why I used parentheses here is just for the sake of explanation. They were not needed. I just wanted you to understand that these are two completely different set of bullions. One does not depend on the other. They are both independent, but they are used to set the proper definition on this statement. It's less than or if it's greater than, when it comes to comparing the data to the minimum and the maximum. With that out of the way, let me right click and run. And there we go. So this is what happens. We start from the end, correct. So we check the minimum valid is 100, the maximum valid is 200. So we shouldn't have any values that are less than 100 or greater than 201. Oh eight is good. One oh two is good. What is the first value that should be removed? 36. So right here, 123. All right. There we go. So you can see 36 was removed, and if we go through this, so we go 1-234-567-8910, sorry, 012-345-6789 I apologize. There we go. You can see that we get 36. The next value would be five. So on this line, we shouldn't see five. We do see a five, but it's the other five. Keep that in mind, I should probably change the example. But yes, in this case, we shouldn't see one of the five. So we have 0123456, and there we go at index six, we've removed five. The next number is 38. It was removed five was removed and the rest are valid. So I've taken you through the process of safely deleting and removing items from a list. I hope you enjoyed. I hope you understood why iterating over a list going backwards and removing items is so much better than going forwards. Thanks so much for watching. I hope you enjoyed. This will be the last video. I know it was a hard path to go through, but you got to the end. Congratulations. And the next video, we're going to learn about nested lists. It means when we have lists inside of lists. So I will see you in a few seconds. 68. 19. Nested Lists: Welcome back my fellow Python developers. In this video, we are going to be learning about nested loops. Let's go ahead and get started. First thing as always, we will want to create a new Python file. I'm going to go into file new, create a new Python file and call it the nested underscore lists in here. First thing I'm going to do is number one is equal to, I'm going to have 23, 416-098-2201 We'll just start a new one. Number number two, we're going to have 20, 131,575.94 These are two distinct lists of integer. Now I'm going to create a third list which is going to be called numbers. And I'm going to say that numbers is equal to the following list, number one. Come on, number two and I'm going to print out the numbers. Now again, I want you to take a deep breath before you run this program and tell me, tell me, just tell yourself what you expect the output is going to be in here. If you notice that we have number one and number two as individual items inside of the list numbers, which means we should have two items inside of numbers which are lists. This is a list of lists, just like we have items inside of this list which are integers, which makes this a list of integers. This is a list that has its items as other lists, which means this is a list of lists. If you figure that out, tell me if you can figure this one out. What if I do the following and I say number underscore list in numbers and I print out numbers list? What do you think the output is going to be? Well, if you guessed individual numbers, you're wrong. If you guessed that it will be just two separate lists, then you are correct. Because remember, when we loop over a list, we get each individual item. We put it in the numbers list variable or whatever variable we've created. When we print, we simply print out that item in here. This list is consisting of two items, and these two items are the following. And you can double check that if you do the following, if I wanted to print out the length of my numbers, what would the output be? If you guess two, you are correct because we only have two items inside of numbers. Numbers is made up of two list. Oh yes. It is made up of two lists and it's made up of two items. All right. If we wanted to get indiumbers, individual items from inside, what would we need to do in here? I'm going to, if you want, you can take a second to try and guess. Okay. So I'm going to create a four individual underscore numbers in numbers list. And I will print out individual numbers if you were able to guess this, congratulations you are on the way of crushing Python development. If not, no worries, start paying more attention. I'm going to right click and I'm going to run and look at the output that we get. So we get individual numbers out of our lists. There we go. Now with that information done, if you're still not sure how this works, again I recommend that you add a breakpoint in here. And you slowly debug this four loop, which has a four loop inside of it, so that you can see how each item is being extracted from there. With that, out of the way I'm going to add, I think I'm, I will comment all of these out. Now let's comment everything out. Okay, And I'm going to create a new list of lists. So I'm going to create a list underscore core lists, and I'm going to say that it's equal to the following. I'll have 268, and here I'm going to 10, 181-316-1819 Again, I'm going to have 2618, 8065 0450 2808 and again 2065. 0280 4909, 1115, 1877. 1516, 1960 2203. And I think I should speed up this part because it's useless. Mr. Editor please speed up the process. 63 18 skin 8450, 2181, 8511, 8808, 74.51 All right. There we go. We're done. And as always, I'd like to add the come up because I can. This is a list of lists. As you can see, we have individual lists all being added into one enormous list. Let's go ahead and print out the list on the lists that don't have 18 in them. I'm going to create this for loop for list, list of lists. I'm going to say if the 18 not in numb list, why doesn't it like numb list? Because in word to, to numb list we'll just start and underscore between list. If 18 not in numb list, I will print out list. If I write click and I run, this is what I get. We only have two lists that don't contain 18 in them. As you can see, all other ones contain 18 somewhere. Now let's also print out the lists with 18 and how many times they occurred. We are checking if 18 we are going to print out the list. Else we are going to print out, I'm going to have my replacement field in here and I'm going to print out the numb list, has 18 appearing replacement field, numb list count 18. We've already seen the dot count and how it works and we've already seen the use of this kind of replacement field with an F on the other side when I write, click and run, there we go. This is our output. We have this list that does not have any 18 in it. We have this list that has 18 appearing twice. 18, 18. This list that has 18 appearing on this one, having 18 appear on this one having no 18, and the last one having 18 appear entire times. I hope you understood. If you're still not sure how this code works, again, I recommend you go through it. You can use the debug, you can find everything that's happening. Because once you do, you have a challenge of removing 18. You need to create a new loop where you loop over the list of lists inside. You need to create a loop going backwards over the range of lists you are in. If the item on the list is 18, delete it from the list and print out the list of lists at the end. Not an easy challenge. Hard, You need to combine a lot of things that we've learned before, but I believe in you pause the video right now and go to the challenge. Okay, welcome back in here. First thing I'm going to do is I'm going to create a for loop with the numb list in list of lists. Actually I'm going to comment this in here or actually you know what, I'll also hold control and shift and move this up, it's at the top. I'm going to say four index in range and the range is going to be the length of the numb list. Minus one, because I want to start at the last one or at the last item. And remember what we're doing in here. We're going forward using our lists. So we're looking at each individual list one by one because it doesn't matter if we start at the last list or at the first list. The items that we're deleting are not the actual lists. They are items inside the lists that are inside list. Get what I mean. For example, it doesn't matter if we start with the last list or with the first list, but when we get to the last list, it's important that we start at the end of it. That is why we have a normal four loop. And then on the second four loop, we start at the end. We want to get to minus one. We want to go until the first element and our index is minus one. In here, I'm going to say if num list at index is equal to 18, then I'm going to delete the numb list at the index. Print out numb list. I'm also going to print out numb list. Not on the if, but in this situation, every single time I finish with a list, I'm going to print it out. Mind the indentation when I write click and I run, this is what I get. First of all, we have 268. It stays the same because obviously there is no 18 there. Next thing I'm going to do is on this following list, I had 218. Now I have zero. In this list I had 118. Now I have zero. And this one I had 118. Now I have 000 in here. We had 418, if you remember correctly, and now we have none of them. I hope you understood how this works. I hope you are beginning to feel how important it is to go backwards in a list. We did not disturb any of the other elements because we were going backwards. Before we finish off, I'm just going to show you another way of doing this. I'm actually going to comment this out in here. I'm going to say four number or four list of lists for number. Numb list. If number is different than 18, I will print out the number and we'll just have a print in here and I write Click and I look at that, I'm printing out all of the numbers and I've removed or I did not print out the numbers that are equal to 18. I mean, it's what you can do is you can start appending your lists in this case, but this is just another cheeky way of not having the 18. It's not a different way of handling this sort of thing, but you can actually then add these numbers into a list if you want. Append different lists. I hope you enjoyed. I hope you are not overwhelmed with all of the information. The next video will be the last video on lists. You will become a master of all of these. We will learn how to use the join and the split methods, and afterwards, we will get into topples. I hope you enjoyed. See you in the next video. 69. 20. Join and Split method: Welcome back my fellow Python programmers. In this video, we are going to be learning about the join and the split method. Let's go ahead and get started. First of all, I'm going to go file new, create a new Python file as always, and call it underscore. Underscore method. I'm going to start by creating my car parts. I'm going to say that car parts is equal to the following. First of all, we have the hood, the wheels, the mirrors, then we have seats, then we have motor, then we have stereo. And at the end, oh my God. Here, first thing I'm going to do is create a variable called the separator. Separator is equal to just a separator, and I'm going to add a space on each side. Next, I'm going to say that the output is equal to the separator join and I'm going to join over the car parts and I'm going to print out the car parts. Or print out, sorry, I apologize, I meant print out the output. If you hover over the join, we'll see that it cactinates any number of strings. And the strings whose method is called is inserted in between each given string. The result is returned in a new string, the join we provided with the. And it should return a concatenation of all of the items that are inside with the separators. In between when I write click and I run, this is the output that I get. We get the hood, wheels, mirrors, seats, motor and stereo with these slashes in between them. We specify the string that we want as a separator inside of the join, and then we use the join to create all of this. Nothing too weird in here. Nothing too complicated. I think it's a very minor method. Let's move on to the split. I'm going to go into file, a new Python file and call this score split core method. Boom, In here I'm going to have a message. The message is going to be, learn Python is easier than you think, but apparently not grammar learning Python is easier than you think I'm going to say. Words are equal to message split, then I will print out the words. If you think I'm moving too fast, Positive video way to write all the code and then look at it again, I'm not doing anything special in here. Let's hover over the split and see what it's all about. If we hover over the split, it says that it returns a list. Uh huh. Before the joint would return a string. Now we're returning a list of the words in the string using sepp as the meaning right here, this variable. And we're going to learn in the upcoming section what these arguments are and how to use them, which is the separator as the delimter can see right here, the limiter according to which we split the string, none. The default value means split according to any white space that you see. And discard empty strings from the result. This is the documentation. If you want to go even further into the documentation, you can click on this link. It will take you to Python's documentation, which is very, very complicated but definitely very useful. Another resource that you can use is W, three schools. In here, I could type in the following. Let's say I want the split method in Python, three schools. The split function, you open three schools and boom, look at that, you find all of the resources that you need. I've obviously covered this before, but this is a great example just to remind you of what you can go through, because obviously I cannot teach you every single small detail in Python. It's impossible. The course would be thousands of hours, so some gaps you need to fill on your own, like the split for example. Nothing too much. The split is very simple. If we go back into our code in here, when I write, click and I run, you'll see that now I have a list of strings, which was each individual item in here separated or split over the empty space. So every single word is a item on its own. The next thing I'm going to do is I'm going to have the message equal to the following. I'm going to have apple, banana. By the way, this is an example that you might see on W three schools, cherry and orange. I will print out the message, split over the hashtag. What do you expect is going to happen? Pause the video, think about it before you run. There we go. We can see that we've split our message over the hashtag. Now, if you would have added a space in here, for example, what would the output be? Come on, think about it. There you go. You'll see that these spaces will be added to our item strings as well, or to our string items as well. I think it's pretty self explanatory. There's nothing too much in here. I'm going to continue on. Let's now work with a join and a list together. First thing I will do is I'll simply add a print in here. And then I'm going to have a number list. And I'm going to say that the number list is equal to the following in here. I think is a great moment for a speed up. Okay, welcome back. After you've typed in this list. As you can see, these are individual items. I've just separated them with extra lines. The difference between this and this is not, you could have just written it like this, but I wanted to write them in this situation. And you'll understand why in just a bit. In here I'm going to do the following. I'm going to create values equal to. I'll have join the numbers list. The number list, I'm going to print out the values. What do you think the output is going to be? While you're thinking of the output, I'm going to do the following. I'm going to have sttocosco values equal to values split. Then I'm going to print out list of values who think about what's going to happen based on what we learned about the join method. By the way, what we said about the method in here, or by searching for the split, you can do the same for the join, by the way. So keep that in mind. Think about what would the output look like if I right click and I run? This is what I get. I get one space, seven space, 843 space, et cetera, et cetera. This is when I used the join. I joined over this space in here, similar to what we did right here. We use the separator which is just, I think it's called the pipeline character, if I'm not mistaken. We use a space, we use the space, pipeline space, and then we use the separator that join the car parts in here. We did the same, We have one, then the space which is right here. Then we had 007 and then a space, and then 843 space in between each character. We just had a space in between each character. That's why we have a space in here. And then we got this output, and then we split this output over its empty spaces, so we created a list of numbers. Now what would happen if I had a space in here? Think about it and tell me. I will write the click, I will run, and this is the output. So you can see we get one, then we have a space, and then we have a space, and then we have a space. What is happening in here? Well, first of all, in between each character, we also have a space. But when we get to an actual space, we have to add a space on the left hand side and on the right hand side. That's why you see these big gaps in here. It's very important that you understand what is happening. I will take this back before we move on. Before we go into the topples, I'm going to issue you a bit of a challenge. You'll need to convert to integers. I want you to convert the list of values we have into integers. Should I give you a small hint? If you need the hint, wait for it. If you don't, and you think you can do this on your own, what we basically want is to convert this into a list. This needs to be converted into a list of integers with these numbers instead of being strings, because notice they are strings. They need to be integers. If you need the hint, I'm going to give it to you in 321. Go through the list and at each index convert the value into an integer. That's basically it. Then put back every single value into a list. This is how you could do it. I know it's on the nose, but pass the video right now and go do each challenge. Okay, welcome back in here. I'm going to do the following. I'm going to say that four in the range is going to be the length of the values, or actually, sorry, I apologize. The list of values, I'm going to go over all of the list of values at each index. The list of values at each index is equal to integer. List of values at the index. There we go. And that's basically it. There's nothing more than that. Finally, we will print out the list of values. And what is it nagging me about? Index. If we hover over it, unexpected, let's run it and see what happens. Okay, it works. But what is the matter with this unexpected type or types? It's waiting for an integer and we've provided you with an integer. So what is the matter in here? It's not complaining in here, it's coming. All chalk it off to a hiccup in the system. As you can see, we have this properly working now. You might have done it in another way. We could have said value underscore list of integers, j is equal to an empty list. I'm going to say four values in list of values. I'm going to take the value list in integers, pend with the integer, all values, print out the value, list integers. So instead of converting the actual list of values, we will create a separate list and put all of the integers inside. Now I right click and I run. There we go. You can see, let me get the same output, ladies and gentlemen. I hope you enjoyed this video. I hope you enjoyed Lists. It was a long, arduous journey, but you got to the end of it and now you have a of more knowledge. When it comes to list, you basically have everything, all the knowledge regarding lists, you probably now know more than 99.9% I don't think so. No, no, I do think that you know more than 99% of the world's population enlists. Congratulations, It's an amazing accomplishment. And the next video, we will move on to topples. And I'll see you then. Take care. 70. 21. Tuples: Welcome back my fellow Python developers. In this video, we are going to start learning about topples. What the heck are topples? They are used to store multiple items in a single variable. Not too many changes from our original lists. It's a collection which is ordered and unchangeable. Mm hmm. Unchangeable, Those are the two key words. First of all, ordered, meaning that they have indexes, they are in an order and unchangeable. Unlike lists where we can change the items in couples we can't. Which means that they are mutable. Correct. So couples are written with round brackets. Couple items are indexed starting with zero. You can create a tuple with only one item inside. Tuple is one of the four built in data types and Python used to store collection of data. The others are lists, sets, and dictionaries. We've already looked extensively at lists. We are going to see sets and dictionaries in upcoming sections, but that is the basics of it. Let's go ahead and start using tuples back in our code. In here, I'm going to create a new Python file, and I'm going to call it tuples underscore Intro here. I'm going to say t equal to a, a. And I will print out, if I right click and I run, this is what I get. Look at that. I have a, B, C, and I have round brackets around them, which indicates to me that this is Apple. But this is not the most correct way of creating Apple. And by the way, we need an extra line, we need to add parentheses around these to properly indicate that we have Apple. And I'll tell you why Python allows us to do something like this where we don't have the two parentheses in here. Again, if I right click, we get the same output. Simply add parentheses around them and you will get the output as a couple. That means whenever you want to pass a literal of a couple into any function, it must always be in parentheses. We'll see what I mean by that sentence later on, what it means to actually send a couple into a function. Let's go ahead and continue on, and let's create some fruits. So I'm going to have fruits and I'm going to say that they are equal to the following. Oh my God. We're going to have, oh my God, why can't I write apple, banana, cherry? Something went wrong with my fingers. What else do we have? Another apple? Yeah, sure. Why not? Apple, ma, and another cherry. Why the hell not? Go ahead. Very creative fruit names. And I will print out the fruits and I will print out fruits at position two, what do you think the output is going to be? There we go, pretty simple. We have a couple of our fruits, and if we print out fruits at position number two, we get cherry. Because just like lists, we start at 01.2 we get cherry. Also, tuples are immutables, as I've told you. Meaning that they cannot change. And I'm now remembering, maybe I said mutable, I hope I did not. But in any case, in here, we know that couples are unchangeable, which means that they are immutable. Which means if I try to do the following cheeky thing in here, fruits, and then I say that fruits at position zero is equal to pineapple. Look at that. Even before doing anything, even before I tried to run this, it immediately gives me a huge highlight. And if I hover over this highlight, it tells me that couples don't support item assignment, meaning you cannot assign anything to it if I try to now print out fruits. When I write click and look at that, I get an error because it's a type error. Topple object does not support item assignment, you cannot do these. I should comment this out. I'll also comment this one out because I don't really need it. We can also convert topples into lists. For example, I can say fruits. Two is equal to a list of my fruits. Let's print out fruit. Click and run. And look at what we get in here. What did we get? I was so confused, like what the hell? We converted it into a list and it doesn't seem like a list, but we were printing out the fruits, fruits to when I write click and at that I get fruits, fruits two is a list. Now we can also convert this back into a topple, so I can say that fruits three now is equal to fruits two. Excuse me, fruits two. Apparently, the heck cup is not just in my fingers, it's also in my brain or my eyes. I will print out fruits three, right click and run and look at that, we've converted it back into a topple. So that's the basics of topple. They are immutable, they have round brackets. And we'll see more uses to our topples in the next videos. But before we go, you need to deal the impossible in your challenge. You need to change the unchangeable. You'll need to destroy the undestroyable. Find a way to change an item inside of the immutable topple that we've created. That is an impossible challenge, I know, but there is a way when there's a will, Should I give you a hint, or would you like to do it on your own? 321, Convert the topple into a list, change an item in that list, and then convert it back into a couple. Obviously, this is something that we will never need to use in real life, but you never know when you might need to change a value in a couple. Pass the video right now and go do the challenge. Okay, welcome back in here, what we want to do is the following. When we change fruits into a list, I will also say in here, print out changing, changing apple to pine apple. In here I will say fruits, fruits two. At position zero is equal to pineapple. And then I converted back into a topple. And now we should have the following, boom, there we go. So we've actually changed our congratulations. Obviously, this is a very cheeky way. We would never want to do such a thing. But it is, everything is possible with Python if you really believe so. An example of the use of couple would be, let's say, date related events. You wouldn't want to have a list that indicates when the event is happening because somebody might come and change these dates and ruin your whole event medicine that somebody should take should be definitely a couple. What else may be money in a bank account for example? Oh no, The money and back and cap actually would change. What wouldn't change would be the transactions that you made. So you wouldn't want to change the amount that you made in a certain transaction. So after a few years, you just have a list and you go in, you remove things, you continue on. These are a few examples I hope you enjoyed. I hope you understood. In the next video, we are going to be looking at unpacking topples and what it even means to unpack. Thanks so much for watching. See you in the next video. 71. 22. Unpacking a Tuple: Welcome back my favorite Python developers. In this video, we are going to be learning all about unpacking topples. Let's delve into it first things first, File new. And we should find the Python file and call it unpacking. Let's just call it unpacking topples so we know what the heck we're even talking about. I'm going to have x, y, and z, and they are equal to 12.3 If I try to print out x, y, and Z, right click and run, and there we go, we get 12.3 Basically what happened in here is called unpacking because as you can see, we have 123 that are a topple. It's the same thing that we did in here when we had ADC, just without the parentheses around them. Xyz are three different variables that were each assigned a value from that topple, meaning that we unpacked the topple, okay? That's basically it. We simply unpacked the topple. If you want to make sure that this was indeed a topple that was unpacked, you can do the following, and the output is the same. We can also unpack any sequence that we would like. For example the following. If we have a data underscore list and it's equal to 123, we could say that we have P Q R equal to this data list and we can print out P Q and right click and run. There we go. The only problem with unpacking a mutable object is that if any changes happened, it could really damage our unpacking. If any changes happen to this data list and we try to unpack it later on into let's say the following variables, we could see that we do get an error. Or let's say for example, we try to unpack a data list that has, for example, like four elements in it, right click and one. You can see that we get an error. Or if we append the data list at any point. Let's now look at a more practical use of unpacking. I'm going to comment these lines out and I'm going to do the following. I'm going to say that we have the alphabet and it's equal to ABC D E F G H I, J K L M N O P Q R S T U, V, W, X, Y, and Z. There we go. We got them all. Now I'm going to say four in enumerate over the alphabet. Oh my God, you're telling me right now, whoa, whoa, Michael, you've clearly done mistake here. When we say enumerate, it returns two things. It returns the index, and it also returns the value. This is clearly not going to work, but what you might not have known, young grasshopper, is that what happens in here is that the enumerate actually returns apple, and that couple is unpacked into two variables. That is what was happening all the time if I just keep it as a single variable, that's why I call it. By the way, look at what we get. We get a topple. I don't know if you feel cheated or not, but this is what happens under the hood. That's why we always have to delve deeper and understand what's happening in Python. As you can see, this is apple. We can unpack it. Actually, you are going to be unpacking it. Your challenge is going to be to unpack the index inside the loop. Unpack the topple into two variables, the index and the character. Print both of them out at every iteration. Pass the video right now and go to the challenge. Okay, welcome back very easily, just like we've done for all of these years. Index character equal to t. Then in here we can say index character. That's basically it. In here we are unpacking the topple into the index and the character. And when we write click and we run, we get this output. Unpacking is very simple, very easy. There's nothing much to it. We will see a lot of examples of unpacking tupples down the line. Not specifically for unpacking, but in situations such as with the enumerate where we are unpacking tupples without actually knowing that we're unpacking tupples, I hope you enjoy it, and I'll see you in the next video, where we will learn about nested topples and lists. I will see you then. 72. 23. Nested Tuples and Lists: Welcome back my fellow Python programmers. In this video, we're going to learn about nested tupples and lists. Meaning that we are going to have lists inside of lists, or actually tupples inside of lists or tupples inside of topples. We're going to see what's going to happen, we're going to mesh everything up and see what comes out. I'm going to create a new Python file that I'm going to call movies Nested Couples. And I'm going to do the following. I'm going to have movies in here and it's going to be equal to the following and magic in 321. Boom. I'm not going to sit down and write everything, I don't want to make the video unnecessarily long, but as you can see, we have individual items inside of the list of movies. We have the name of the movie, for example, Sha Shank Redemption. Amazing movie by the way, the producer or director is Frank Drabont, and it was made in the year 1994, Silence of the Lambs, Seven, The Shining, and Deer Hunter. All of them amazing movies except for deer hunter. I don't know why, I just didn't like it that much. But anyway, if I try to print out the length of movies before you run, please think of what the answer is going to be. If you thought five, you'd be wrong. There are 15, because notice that there are no indications of a list or no indications of a topple in here. In order to fix this, we need to make all of these into okay, wait. Into a topple. There we go. And as we're creating or making these topples, why would we want the movies to be topples and not lists, if you said? Because the name of our movies are never going to change and the directors of our movies are never going to change and the year that the movie came out is never going to change, then you would be correct, because we will never change the name of the movie, never change the director, and never change the year it was made unless there is some unforeseen consequences. I don't know the name of the director turns out to be wrong or something. Regardless, we would always have the same year, same name, and same movie director. That is why having a topple is a good idea here. Now if I rightly, can I run look at that. I get five instead of 15. Now we want to dissect this. I'm going to create a four loop and say four movie in movies and I'm going to print out the following. I'm going to have a replacement field, first of all, I'll have name replacement field inside. I'm going to have movie at position zero, Mm Hmm. Then director to Dots movie at position one. And then year two, Dots placement field movie at position two. There we go. Now when I write Click and I run, this is the output that I get. Let me also jag it right here, we get the following. We get name Shashank Redemption director Frank Arrabon, year 94, name Silence of the Lamb director Jonathan Demi, the year 1991, et cetera, et cetera, et cetera. But as you can see, it's not very clear what the information is that we're trying to extract. What I mean by that is like what is movie zero? What is movie one? What the heck are we even doing in year? A better way of doing this is instead of having movie zero, I could have movie name underscore name instead of director. I could have underscore name instead of the year. I would like to have just hear all I meant. Instead of movie two, I would just like to have the year. But obviously, the keen eye the viewers of you would have noticed that we have an error in here. Yes, the three big huge lines under the variables probably gave that away. But as you can see, we cannot simply do that. We need to actually have the variables. And it's going to be a challenge for you because I'm feeling lazy today. You will need to fix the errors. First of all, you need to find a way to fix the error in the most efficient way possible, Unpack the pack. And there are two ways of doing this. Should I give you the ways? If you don't, you can just go right now and do the challenge if you want. This is sort of a hint, the two different ways are 321. Boom. Inside of the loops using variables or in the actual loops, similar to the enumerate, pass the video right now and go do the challenge. Okay, welcome back. So the first way is inside of our loop. So we simply say that we have the movie copy, copy, movie name. Come on, director name here equal to movie. And we simply unpack this, because remember this is a topple that can be unpacked. Now when we say name, movie name, we know that we are getting the movie's name. We're trying to print out the movie name. Not just movie at zero or movie at one. We know what is being printed out. When I write, click on, look at that, everything looks fine. But this is not the most efficient way. The most efficient way is doing it directly in here without having to go through the movie just right here. Four movie name, director name and hear. Similar to what we did with the enumerate, right click run, and there we go. So this is the basis of nested loops, I mean nested tupples lists, as you can see, we have movies, we have lists. This is the almost last video. In the last video, we are going to look deeper into nesting. I'm very excited to see you there, and I will see you in a few seconds. 73. 24. Deeper Into Nesting: Welcome back my fellow Python developers. In this video, we are going to start looking a little bit deeper into nesting. The first thing that we want to do is we want to upgrade our movies. How about that? We want to have also a list of actors before we start thinking of how to add them and whatever. We want to have a mini challenge, it's not written down, it's something for you to think about on your own. What would we use to hold the actors? Should it be a couple or should it be a list? Or could it be a list of couples or a couple of lists? I'm just going to tell you that what we'll do is we're going to have actors with a number next to them. We will have the name of the actor and next to them we'll have the number attached. This number is going to be the ranking of the actor based on his popularity in the movie. Think about it. Should be a list of couples, couples of lists. Just Apple, what do you think? Let's see. I'm going to go into file new and I'm going to create a new Python file that I will call Nested underscore data. Inside of this nested data, I'm going to do magic copy and paste. Oh wow, Where did all of this come from? I'm going to provide you with these. I'm not going to leave you hanging if you do that, do not find these right here and you don't want to write them down yourself, please contact me over any way that you can or you can go into discord. I think you'll have access to that discord, please. Whenever you need, whatever you want, let me know. So in here as you can see, we have the Shaw Shank Redemption, we have Frank Daramore, and we have 1994. And we also have a list of actors. And these actors are individual toupples. Now why is this a list of toupples? First of all, we would like to have them as stupples. Because as always, this is not ever going to change. Now you might be thinking, well, maybe the popularity of Morgan Freeman will wane against the popularity of Bob Gunton. But we're just going to assume that this is not going to change. You know Morgan Freeman is never. Do you even know who Clancy Brown is? I dare you, I double dare you. Anthony Hopkins will always be more popular than Jodie Foster, even though that's debatable. But definitely more popular than Brooksmith, Brad Pitt. I mean, come on, and then we have Jack Nikon. No debate there. But in any case, let's just imagine that these will always be the same. This should be a topple, And because we might want to add other actors to this list, that's why we've made it into a list and not Apple. That is the explanation of why we should have a list of topples. Next thing we want to do is we want to print all of this information out properly. I'm going to say four name direct year actors in movies. I am going to print out the following. I'm going to have name two dots, replacement field with name inside director to dots. Director, this is called a column, two dots, this is two dots. When you have two dots like this, maybe I should stop calling them at least vertical dots or vertical two dots. And finally, actors column. And we'll have the actors. We've basically unpacked the top, which is the movies, into the name director I might not have mentioned in here. Notice where the topple begins and ends. If you click on one of the parentheses, you'll see where its other brother is. Right here, the Shashank Redemption, Frank. More comma 1994, the list. And then we have the topple ending. We have the stopple closing down. Right here when I write Click and I run, this is what I get the name, Shashank Redemption director Frank Ramre Year and the actors. And you'll see that the actors are printed out in this way. Not a very nice way, but we get the pot. We can have multiple actors in here as well. We can access any particular movie and get the information from it. What I mean by that is, for example in here I'm going to print out and I'm going to say that we have a particular movie equal to movies at position number two and I will print out. The movies, I print out the movie. So when I write Click and I run, this is what I get at the bottom seven. David Fincher 1995 and then the list of actors. But what if we wanted to access individual actors? First of all, let's say I want to access the actors. I would do the following. I would say a equal to movie at position one. Keep in mind I have access to the movie which is a topple, and then I access actors. Or I say actors equal to that movie at position one, because I have, excuse me, it should be at three. Very nice. Move Michael in, here's 012. And then three, we access these elements. I flint out the actors, right click and run and boom. There we go, We have our actors. Now I want to access one of the actors. I would say actor equals actors. And then I would access number one. Now I will print out the actor right click and run. And there we go, we get Morgan Freeman. Or if you want, you can get Brad Pitt. You can even get Kevin Spacey. There we go, bit. Now I have a challenge for you that you've seen how we can unpack the topple slowly, and by the way, if you want, you can also print out the actual name. For example, in here, underscore name equal to A at position one, and we print out the actual actor name. Now we exactly have Brad Pitt without any parentheses or any columns. I hope you understood how this works, because now you have a very fun challenge, which is to find and print out the actors. Print out the following three names, Danny Lelloyd, Tim Robbins, and Scott Glenn. You'll need to use the same method that we've used right now to print out all of these actors. Post the video right now and go do the challenge. Okay, welcome back. So, let's go ahead and get started. First of all, we have Danny Le Lloyd. Le Lloyd. Is that how you write it? Yes. First things first, we need to find this man. Where is Danny? Danny? Danny, Danny, Danny, Leo. The man is in the Shining. Which means it should be movie equal to 012. How many movies do we have? Let me check, 0123. All right, movies at three. Next we want to get the acts, which means we need movie. Keep in mind movie movies, 012.3, There we go again. Three. Then we need the actual actor, which is actors. Then we need 012. All right, two. Finally the actor underscore name is equal to act at position, which one was that one, I think. Yes, one. The 321 print out. Ace. This works? Yes, there we go. We get Danny Lee Lloyd. Now we need to go to the next name, which was, what was the name? Tim Robbins. But before I do that, I want to show you a much easier way of doing this. I can say that I have Danny underscore Lee Lloyd equal to movies parentheses, three parentheses, three square brackets. I mean, square brackets, two square brackets, one. If I print out Danny Le Lloyd, right click, run, look at that. I can go and delve deeper into my list using these or multiple brackets, one after the other. Let's find Tim Robbins. Tim Robbins is Tim Robbins is in the Shawshank Redemption. It should be zero. Then we will have actors at three, always. Then we have Tim Robbins at one. And then 10311 in here, I'll say Tim underscore Robbins is equal to movies 080. Oh my God, please. 03. What did we say Tim Robbins was one and then one, and we'll print out Tim Robbins. Let's see if this works. Yep. There we go. Tim Robbins And the last name was Scott Glenn. Where are you squat? Scott Glenn. Scott Glenn is in the movie where Scott then do we even have a Scott? There we go. Here it is. In the Silence of the Lambs one, it's 13012344 is that correct? Yes, it is. Because these are number one. They start at one, which means this one is definitely 4,134.1 The last or these two numbers never change in here. I'll say Scott Glen equal to movies. What did we say? 1341. There we go. Scott Clam. Ladies and gentlemen, I hope you enjoyed. I hope you got to the last video. This has been an amazing journey. We have finally finished lists and topples. You are slowly but surely becoming an amazing Python programmer. I hope you're enjoying the scores. You're getting tons of information out of this. And I will see you in the next section where I believe we will start talking about functions. Very important section, very important lessons we're going to take. So I can't wait to see you in the next section. Pat yourself on the back. You are doing incredibly well. I will see you then. 74. Section 6 - Functions | 1. Defining a function: Welcome back my favorite Python programmers to a brand new section where we are going to start learning all about functions. So we're going to be defining functions, understanding parameters and arguments. We'll understand what calling functions is. Returning values, not returning values, handling invalid arguments, et cetera, et cetera. So without any further ordo, let's go ahead and get started. First of all, let's explain or let's define what a function actually is. So what the heck is it? A function is a block of code that performs a specific task. Just like we had blocks of code in our statements, just like we had blocks of code in our four statement. Now we have blocks of code inside of a function. You can pass data through, or known as parameters into set function. A function can return data as a result. A function only runs when it's actually called. Functions provide better modularity for your application and high degree of code re using. What do we mean by the following? First of all, we can pass data to it. So imagine a function being like when you try to sum a few things. When you want to sum two elements, let's say 2.5 you're providing data to a function that is sum. You provide it with a two and then you provide it with a five. And the function adds them together and the function can also return data as a result, meaning that you provided it with a two, you provided it with a five. It adds them up, it gets to 7567. Yes, that's right, and it returns that result, meaning that it gives you back data, which is seven. A function can only run when it's actually called. Meaning that let's say you have this some function. It will not be called on its own unless you tell it, unless you specify that you are actually trying to call this function. And finally, functions provide better modularity for your application and a high degree of re, using, meaning that first of all, modularity means it's a technique of splitting a larger program into tasks that are smaller, more separate, and easier to manage. Let's say instead of having to use plus every single time, you can just create a function that you can use whenever you need to. This will allow you to make one small change in order to fix all of the issues that you. We'll see where this becomes very helpful and you also can reduce it many times. We've already said that. Let's look at a functions structure. This is the typical way that we would create a function. We define it using the deaf. We have the function name, the argument, the function body, and a return value. Deaf is the keyword used to declare the function. Function name is the name of the function or the name given to that function. Usually, the function name should reflect what that function does. The arguments, it's any value that is passed to set function and the return which could be optional, which returns a value from that function after all of the code has been processed. As I said, you can sometimes return things. You can not return things if you don't want. And it's very important to also know that you need to leave some spaces. I'll tell you what, that with that small introduction into functions, let's actually get started. Last time we were in here, I'm going to create a new project. Now, I might have changed code updated course, I don't know. Some things might have changed. Don't worry. Go to project, make sure that it's Python. I'm going to call this one functions in Python and I'm going to select the appropriate file, so it should be in D Python course. In the code. In the code, I will create a new folder which is going to be functions in Python code it. Okay, let's finish up. Yes, this window, I'm going to create a new project. New project. And right here, make sure that it's a Python project. And I'm going to save it inside of Python course. Inside of code, I will create a new folder for this. Call it functions in Python. Copy this, okay. Okay, and also copy it in here. It's not changing for some weird reasons. Again, let me make sure that we've selected Python functions. Okay, finish up this window. There we go. We should have everything working properly. Let's go ahead and get started. First things first, we're going to create a new Python file. We click again in here. If it's not showing, let's click on this. Python file. We're going to call this intro underscore functions. Let's go ahead and create our first function. Our first function is going to be a very simple one. We're going to define addition in here. I'm going to have the result which is equal to 10.5 plus four and I am going to return the result. Then I'm going to close down the project so we have more space. And I will have the answer equal to just addition and print out answer. A few things to note. First of all, we have this squiggly line. If we hover over it, it tells us step 8305 expected two blank lines after a class or function definition found one. What they're talking about is this empty line. We always need two lines. When we hit enter, we have a space. There we go. Whenever you define a function or a class, we'll learn later on what a class is. You always need to have two spaces. Then we define the actual function. In here, we said the def keyword addition to round brackets. Result equals 10.5 plus four and we returned that result. Finally, we actually called this function. The function will not work on its own unless it's actually called. When I write click and I run, this is the output that I get, 14.5 Pretty simple. Nothing too much in here. Now what we want to do is we're going to issue you a bit of a challenge. Your challenge is going to be to do the following. Create your own personal function. Create a function with the multiplication. This function should multiply two numbers of your choice and return a result. And call it in your body. In the body of your code. When I say body of your code, it means anything that's outside of the definitions of functions that we have at the top. Print out the result. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? In here at the top, I will define multiplication. And I'm going to have the result equal to 10.5 multiplied by four. And I will return the result. And we also need to have two blank spaces between our functions as well. I'm going to change this from addition to multiplication. Now when I run, this is what I get, 42.0 You'll notice that even though it's 42, we also have the zero, meaning that whatever the result is, what it will return. The result is a float. It returns a float. That means the answer is a float. That means we print out a float. So I hope you understand how this works. As a small homework, I recommend that you add a breakpoint right here next to answer, so that you can see how the program actually functions. So answer calls multiplication, we go to the multiplication, We go through the result, and then when we return, we go back to this exact line. So this will be like a small homework that you can do to make sure you understand how Colin functions works. Functions are not that hard, as you've seen. There are a few things that we need to know about them, but everything will be fine, trust me, don't worry. So I hope you enjoy it. And I will see you in the next video where we will look at parameters and arguments and understand them fully. So I will see you in a few seconds. 75. 2. Parameters and arguments: Welcome back my fellow Python developers to a brand new video. And in this video we're going to learn all about parameters and arguments. Our current function isn't really useful since we can just avoid using the function. In this case, what we want is we want to actually start adding parameters and making it more useful. Not only that, we are just adding two numbers, ten point 5.4 or multiplying these two numbers, which is not really efficient. We want to be able to add, for example, two numbers that the user would provide us with. Let's go ahead and do that. To start changing this, we're going to go back to our function, which is the multiplication, and we're going to provide two parameters. The first parameter is going to be x. The second parameter is going to be y in here. Instead of multiplying 10.5 with four, I will be multiplying x by y. There we go. And then I will be returning the result. Now whatever values we provide will be used in this function, multiplied together and set to the result and then returned. Now notice as soon as we do this, this no longer works. If I write click and Iun I get an error because it tells me there's a type error multiplication missing two required positional arguments, x and y. So we have to provide it with these arguments. I'm going to provide it with ten point 5.4 So basically we haven't done anything but we did provide it with the numbers. And now there shouldn't be any error. And now we get 42.0 Now I can change this to let's say a 6.8 And I right click and I run, look at that, 27.2 I can change the four to 12, right click and run 81.6 So as you can see, we've croof created a really effective multiplication function using a few arguments and parameters. Obviously also what we're doing is we are providing this function with a float number, which gives us a float number in return. But if we provided with an integer number or in two integer numbers, we should see that we have an integer output. That's the basics of having two arguments. Nothing too much in here. I'm going to give you a challenge to help you better understand how this works. I'm going to show you in the slid, you have to create looping functions, create a four loop over a certain range. This should happen in the body of your code. Again, concentrate body of your code. Use the value in the loop as an argument. In the multiplication function, you have the value that's increasing or decreasing or whatever you want inside of your range. The value that is changing needs to be used as an argument in the multiplication function, Print out the resulting answer every iteration, and that's basically it. Pass the video right now and go do the challenge. Welcome back. How did you get on with that in here? First of all, I need to create a four loop. So I will say four valve, meaning value in range. And the range will be 1010, we are going to go from zero until nine because remember it's always up to, but not including. And I'm going to say table underscore value is going to be equal to multiplication to valve. Then I will print out the following two things. I'm going to say two x which stands for multiply with the replacement field of val will be equal to replacement field table of value. So what we should see is we should see two multiplied by zero equals zero multiplied by one equals to multiply, blah, blah, blah, blah. Right click run, and there we go. It works two multiplied by 02 multiplied by 12 multiplied by two until two multiplied by nine. As you can see, providing parameters is very helpful. A function that does not have parameter can still have its own place in existence, but it's not that efficient. Before we move on, let's go ahead and create some debugging. Let's do some debugging for our values. So I'm going to first of all, add a debugger in here, or maybe I should add it right here. It doesn't matter. I'm going to write the click and I'm going to run, sorry, I'm going to write the click and I'm going to debug. Boom, This is where we start out on the multiplication. On the answer. Now if I step into, look at what happens, I go to the top, into the multiplication. Pretty obvious, if you've done the homework, the small homework that I gave you before, you should be familiar with this. So let's see what happens when we step in again. Oh, sorry. Before we step in again, look at what happens in here. We have x six and y 12. So they go to their respective positions. So the first argument is going to go to x, the second argument is going to go to y. We step into again, there we go. The result is 72, and then we go back to the multiplication to set the result to the answer. If I step into again, look at that, answer becomes 72. But notice something very important that happened when we actually went out of the multiplication function x and y disappeared. Why is that? Well, because in this case, X and Y are just temporary variables. They're not set to anything, they've not been properly created or defined. They are temporary. Once the function is done, they are deleted. And what I mean by that, and it's very important to know this distinction, because now if I try to, for example, print out x, look at that, there's nothing, there's an error. Because x does not exist in the body of my code. It is only defined inside of the multiplication. It only exists in this boundary and does not exist on the outside, okay? So very important thing to note. You cannot use your variables, your parameters outside of the actual function. To whom, who, or I don't know where it belongs. Okay? So I hope you understood parameters and arguments. It's not that hard, it's kind of easy. I recommend that you also, as a small homework, you can use the debugger right here on this for loop. Go through it, make sure you understand what's happening, how these values are changing, and how they are also disappearing and cannot be used outside the bounds of the. I hope you enjoy it. I'll see you in the next video where we will be creating a word reverser. That should be fun. So I'll see you in a few seconds. 76. 3. Word Reverser: Welcome back my fellow Python developers. In this video, we are going to be creating another function that will demonstrate how we can actually, we use functions in a more meaningful way. Because currently the multiplication that we've created and the addition are functions that already exist in Python. So we want to create one that's unique. The first thing we're going to do is we're going to go into file new and create a new Python file that we'll call word underscore reverser. Reverse sir. First thing I'm going to do is I'm going to define the reverser. I'm going to provide it with an argument. It's going to be the string underscore two, underscore reverse. Then I'm going to say that the reverse underscore string is equal to the string to reverse. And we are going to slice it the following way. And then I will return the reversed strength, and that's basically it. Can you tell me what this does right here? I want you to take a few moments and remember how slicing works and this exact slice does. After passing the video and thinking about it, you've probably concluded that what we're doing in here is we are starting at the beginning, going until the end, but we're doing a step of minus one. We're going back through the string that we would like to reverse. When we have a step of minus one, it means that this is the end and this is the beginning. Basically what we're saying is that the reversed string is equal to a slice of the string that we want to reverse, but when it's going from end to the beginning, and that's basically it. But because we don't know the size of our current string or the string that we want to reverse, we do not specify what the end and the beginning or we just tell it that we want to go from the end until the beginning. And then we return the reversed string. With that out of the way, I want to show you one thing that we could do in here to make this more efficient. Instead of setting the string to reverse with its slice in a variable, what I can do is I can comment this out. Remember I can comment out a line with the control forward slash. I think I've already mentioned that before, but no worries. And I can simply return the reversed string directly. This doesn't change anything. The function will work the same way it did before, but it will definitely provide a easier to read and more efficient function. Now that we have that, let's go ahead and create word, which is going to be equal to an input. That input is going to tell us. Please enter a word you'd like to reverse. The word that we would like to reverse will be added and finally we will print out your word was two dots replacement field with the word when reversed, it is two dots replacement field. The reverser provided with the word. There we go. We obviously should add an extra space. If we write click and we run, Please enter the word that you would like to reverse. I would like to reverse. There we go. Looks like it doesn't work because, look, your word was rotator and when reversed, it's rotator. Well, actually I made a mistake, but I deliberately chose a word that actually is the same, going forwards and backwards. A small joke in here. No worries. It's April fools. I'm kidding when I'm recording this. So let's try any other word. Let's Michael, there we go. Look at what we get. A I don't know. So as you can see, the word reverse or works properly, the only problem with it is if I try to enter the following word rotator. But with a upper case R, you'll see that I get an upper case R at the end, which doesn't really make sense. It just doesn't look good. To fix this, I will issue you a challenge, which is going to be to mind your case. Reverse the word without having to worry about the case meaning, Make sure the returning value is independent of the case of the characters. Pass the video right now and go do the challenge. Welcome back my fellow game developers. So how did you get on with this challenge? This is a very important challenge because some of you might have done the following. You might have used case fold in this situation so that you can lower the case on the input directly, which would work. You might have used the fold right here, which would have taken the reversed word and lowered the case, which would also be good. But the best place to put the case fold is if you haven't put it in the correct place. Thank a little bit, it's actually here. What we want to do is we want to reverse the word and then apply the case fold to it. Now you might be asking yourself, why isn't it good here? Why isn't it good here? Well, because later on we might use the reverser again. Do you think we should apply the case fold again to when we're printing out the reversed word? I mean, we can, but what if we're calling the reverser 1,000 times? Well, now we'll have to make sure that we type in case fold every single time. And those 100 times, 100 or 1,000 times, this is where the power of functions come into play. This is what we meant when we said reusability and modularity. Instead of having to call the case fold every single time you try to print out a reversed word, you can now simply use it one time inside of the function and it will always work. I will copy the rotator, Run paste the rotator. Hit Enter, and look at that. Rotator is printed out with the lower case R. Now let's just make sure that it works also for Michael, for example. There we go. You can see that no big M, which makes sense. So I hope you enjoyed. The most important part in all of this video is for you to understand the importance of using a function and how easy it is to modify code that you might use repeatedly throughout your program. I hope you enjoy it. I will see you in the next video where we will learn about functions. Calling functions, you can call it functions inception if you want. All right, I'll stop here and I will see you in a few seconds. 77. 4. Functions Calling Functions: Welcome back my fellow Python programmers to a brand new video. In this video, we are going to see how functions can call other functions. Let's go ahead and get started. First thing we're going to do is we're going to go into file, new file. I'm going to call this underscore calling functions here. I'm going to define multiply. The multiplication is going to be between x and y, and it will simply return x times y. Pretty simple. Nothing too much in here. Now the other function that I'm going to create is going to be define get underscore power. Underscore two. We're also going to have x and y. Remember, these two, x and y, are independent of each other. The get power is the best example of a function being called inside of another function. Because when you try to get the power two of something, you multiply it by itself by the time that you've provided it with. That came out completely wrong. Let's say you have two to the power three. You would multiply two by two by two. Usually the symbol of the power two would be this means that it's equal to, actually let me comment this out. It's two multiplied by two multiplied by two. What is happening in here? The multiplication function is being called three times. First of all, it was two multiplied by one. To make it more obvious on how this is going to work, one multiplied by two, then two multiplied by two, then two multiplied, or the entire answer multiplied by two. Again, the get power is a very important or a very good example of using a function or calling a function inside of another function. First thing we're going to do is we're going to create the result which is equal to one. This is just to set things up. Then I'm going to say four in range, and the range is going to be y, so it's going to be x to the power y. We're going to multiply x by the results that we are getting, y times four in range y. The result is equal to multiply result x. I will print out the result. This is purely for debugging purposes, purposes that purposes yes, it is. Finally, outside of the for loop, I will return the result. Now in here, after two lines of code, I'm going to print out the following. I will say five to the power three is replacement field and then get power 53. If I write Click and I run, there we go. Five power three is 125. And that's true because five times three is 25. Then multiplied by three again, multiplied by five again, I almost lost it. There is 125. I want you to look closely at this, get power, and truly understand how it's working. Basically what we're doing, as we said, if we put back our example of five power 35 to the power three is equal to one times five times five times five. The result is one. We take one, we multiply it by five. We say that the result now is equal to multiply result is one axis five. We go to the multiply, This is where we're calling the multiplier function. From another function, we get five. Now the result is equal to five. We go back through the loop, we check is less than y, which is three. Y is three. And remember, the range is up to, but not including. We started at I equals zero. At I equals one, no, it's still less than y. We have the result equals five. We say that result, the new one is equal to multiply result which is five to the power three, the power five. Now we have this. We set it back in the result, now the result is 25. Now we go back and we do the same thing and we have a function calling another function. It's pretty simple. Nothing too much in here. You might be thinking, how is this simple? I didn't understand anything. Once you understanding understand it through the next challenge, you'll tell yourself, wow, this was indeed easy. Because your challenge is going to be to use the debugger and understand this. Use the debugger to go through the code and see how the logic is working. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? Pretty simple. Nothing too much in here. I will add a break point right here, exactly on the print. And I will debug the code. And let's look at how everything is working in here. I will step into, there we go, we go to the top. As you can see, x is equal to five, y is equal to three. We step into again, the result is one for I in range is equal to zero. Look at what's going to happen when we execute this following line. I will jump into the multiply and look what we have in here. Return x multiplied by y, something that we might not have seen before or you might not have realized when you're debugging your code when working with a function is that we don't hang up on the function, we immediately go inside of it. Something that might be obvious to you, but something very important to realize. Just like when we skip over the ls, we don't execute the ls, we go inside of it and execute the code that's inside, return x times y. Notice when we come back, we don't come back a line to the front. We don't go back to the print, we stay on the result. And this is something that you've probably seen as your debugging your code in the previous sin or two videos before. Y equals three, x equals five. Now we have the result equal to five we printed out in the debug. Now y is one, result is five, or result is equal to multiply. Now what do we have the result as? Boom, there we go. This is five multiplied by five. We come back, it's 25. Now when we go back to the top, there we go, x is 25 multiplied by five is the return of 125. We print out the result and we go back. We increase I. We see that it's no longer exactly less than Y or less than the range, and we print it out. I hope you enjoyed it. If you're still not sure what's happening, go back through the code debuckt again, understand everything that's happening. And I will see you in the next video where we will look deeper into returning values. So I will see you in a few seconds. 78. 5. Returning Values: Welcome back my favorite Python programmers to a brand new video. In this video, we are going back in time. We're going back in time to this following program, the old Nicholas Flamel. The problem with this is that if we use a string in here, we would get an error. Don't believe me. If I write click and I run what is flames H, I could type in a number that I already know. But if I type in, for example, high and hit Enter, look at that, I get an error. What is this error all about? Well, the problem is that we are trying to convert whatever the input is into an integer. But if you provide it with a string, as you can see, you get an error. Because how do you convert high into an integer doesn't make any sense. In this video, we're going to learn how we can create a function that can help us a lot because we're going to create a new Python file. This new Python file is going to be called, what shall we call it, Nicholas? Underscore flamel. Underscore underscore function. Or why am I calling it just underscore function it in here. The first thing that I want to do is I want to define a new function. I will define the get underscore integer. This integer will ensure that what the user is providing is indeed a number. In here, I'm going to add an argument, which will be the prompt. The prompt, The prompt is the following, right here. When you say, let's say in here, I want to get input. Provide me with a gas, for example. This is called the prompt. We are providing the get integer with a prompt. You should answer me by the time we're done. Why we're providing the prompt to the get integer next we have a while true. We're going to keep on with this while. We're going to have Tamp, which is a temporary variable Tamp input prompt. We're going to have the input with the prompt inside of it and we're going to check if stamp dot is numeric. Do you remember this function? Very, very old function. I told you we're going back in time in this video. Return in and then temp. Look at this and tell me what is happening in this function. Take your time. Now the only thing that might be weird about this is there's no break in here. This is a wild true, It will keep going forever. What's going to make this wild loop stop? Well, it's going to be the return, because remember when we return a variable, we jump out of the function, which means we will effectively jump out of our wire loop. So this is a great way of avoiding the use of a brake. We can simply use the return. Now that we have that down, I'm going to get this code and I hope you can find it somewhere in your project. I honestly, I can't name which section it was in right now. You'll have to try your best to find it. I apologize. It should be somewhere in here in the project. Go to file open recent and find the project that you're looking for. What I'm going to do is I'm going to copy all of this right here. But to be fair, do we really need all of this? Yes, we do. Let's go. No worries. So I will add all of this in here. The import, what is it, level Import at the top of the file. All right, so there we go. Import should be at the top and then have two spaces and then only have two spaces. Okay, eight. I've given you anything. I've subjected myself to your wills to all of your needs. I in your highest 101 actual age one, and the highest guess, none. Okay. Everything should be true except for this right here, where we say that the guess is no longer equal to the input is going to be equal to get integer. The prompt should be just the following, because remember we're printing out what is Flamels age, Mr. Weasley right here. Now we could do it inside in here, but I just want to keep the code as it is so that we just make the little changes that are needed. If I write click and I run. Let me just duck this right here. What is Flam Mel's age? If I type in, let's say 20, it tells me, please guess higher if I type in high, Look at that, There's no error, but it does not work. Michael Python. Can I please play? Nope. It will wait for another number which is 53. I think it's 53. As you can see now we have a functioning program, or at least we have a error free program. The question that I asked you, why do we have a prompt in here? Well, because of the last lesson, you should know by now that we are going to be using the get integer in a lot of places, not just in this situation right here, because we're going to be using it in a lot of places. We're going to have different prompts. Let's say for example, we use it right here just for this forward slash. But what if we change our mind, and now we want to print this instead inside. This completely changes everything, right? But what if we use the get integer in another place? Providing the get integer with a prompt is a good idea because now we can use it dynamically wherever we want in our code. Before we leave, there's one more thing we need to do in here, or at least you need to do in here. And that is tell the user, because you'll need to add a message to the function that tells the user the input is invalid and what he should be doing, he or she test it out and make sure that it works properly. Basically, as you've noticed when we try to add Hi or Michael or can I please play, the user just doesn't know why the game keeps kicking him out. Help the user. This challenge is very important to know where you should be Adding this in your code, Pass the video right now and go do the challenge. Okay, welcome back in here. If we have the under the Ls we are going to print out. Please enter a value. There we go. What is the matter with this expected two dots. Did I seriously forget a colon in here? When I write click and I run, What is age? It's Michael. Please enter a numeric value, Hi to. All right, there we go. So my game works. Thanks so much for watching. I hope you enjoyed the video. I hope you understood the importance of using the prompt in here and you are beginning to really feel how important functions are to us. In the next video, we are going to look at returning none or returning nothing. Thanks so much for watching. See you in a few seconds. 79. 6. Returning None: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to learn what it is that is returning none. All the functions that we've seen so far have always been returning a value. Like right here we have a return, right here we have a return like the word reversal. We're always returning something. But what would happen if we don't and would it really help us with anything? Let's create a new Python file in here and call it non underscore. Returning underscore functions. By the way, you can call these Python files whatever you want as long as they are in line with what's going to happen inside of this. Let's define again the multiply. The multiplier is going to have x and y. The multiplier will get x times y. And we will actually, let's turn the x times y. There we go. Everything is good in here. Life is amazing. And I will simply print out, or first of all, I'll say answer equals to multiply four by 16. And then I will print out the answer, Life is good, everything is good. When I run, there we go, we get 64. Hopefully, that is the answer. Now, what would happen if I decide to comment this out? Well, first of all, I'm going to have an error because you can't just leave a function empty. We have to provide it with something. So I'm just going to say that the result is equal to x times y. Okay, There we go. Now, no more problems. What do we have in here? Multiply doesn't return anything. Uh huh? The multiply does not return anything. Setting this, nothing that's being returned to a variable is not really smart, is it? We need to figure out a way to make this a little bit better. How? Well, what would be the use of a function that does not return anything? First of all, we would probably not want to set any variable to it. Second of all, I will probably remove the print in here. But what would we do in this situation? What is the multiply good for? Well, I'm going to tell you that the multiply in this situation is not completely useless because you can use them to perform certain actions like you're going to learn this challenge could transition, I don't know, no result. Still get something. Since we're not returning anything, we still need to get something displayed. Which means what should we do? Should I give you a hint? If you don't want the hint and you want to try to solve this on your own, it's a bit of a weird challenge, but you can go and solve this on your own. Simply print something out directly into the function, and that's basically it. If the function does not return, we want to print something out of this function, pause the video right now and go do the. Okay, welcome back. How did you get on with that? I think this is very simple. I can simply say the result of the multiplication is replacement field result. And that's it. Now when the multiply is called, it will multiply these two numbers and then print out the result directly. So not returning anything has its uses sometime. I hope you enjoyed this was a very short video. In the next one, we will be handling invalid arguments. Meaning what if I provide high, high, high, theoretically. Can I run well in this case, there we go. Look at what we got. But what would happen if we didn't want to get this if we don't want a string? We'll see that in the next video. See you in a few seconds. 80. 7. Handling Invalid Arguments: Welcome back my fellow Python programmers to a brand new video. And in this one we are going to look at handling invalid arguments. I've already told you about what happens if we provide this with a string. We get an unexpected output. But this is not as bad as if we have the following. If I provided with this, if I provided with two strings. Now when I write clicking on look at this, I get an error. This is not good at all. We don't want something like this to happen. We're going to look at how this is fixable. The first thing I want to do is I want to uncomment returning x and y and comment out the print. Then in here I'm going to print out, give me or give us two numbers to multiply. In here, I'm going to say that a is equal to an input and then a two dots and B is also an input. Before I continue, I'll just make them into an integer. Now I know we've learned that this is not the most optimal way because the user can still provide a string. But for the purposes of this video, we'll just assume that the user knows he should be providing a numeric number. So now instead of number, if we try a string, we get an error. Obviously, this is because of the integer that we are providing this with. But what if we wanted to create our own kind of error? For example, let's say we can only multiply everything. Or we can multiply only if x is less than ten. Let's say this is what we want out of our program or out of our function. This is exactly what you are going to do in the challenge of creating your own type error. In the multiplication function. Multiplication function, make sure that the numbers meet a certain condition. Example x or y are greater than 100. Use the raise value error if they are. Otherwise, calculate the result and return it. Google it and understand how to actually use it so you can type in value error W three schools to really see how you can use the raise value error. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? Let's say we want to only multiply x and y if they are less than 100. What I'm going to do, and I hope that you looked up the raise value error in here, I'm going to say if x is greater than 100 or y is greater than 100, I'm going to raise value error and I'm going to say one or both of the numbers. Let's just make it a legit error. Numbers one or the both are greater than the max size 100. And there we go, that is what we need. And then finally in here we'll have an L and we'll just tab everything. So now we have our own error. Ladies and gentlemen, if I right click and I run and I provided with 506, I don't get anything for some reason. What is the issue in here? Uh huh. Well, the issue in here, ladies and gentlemen, is that my tired head has forgotten to do multiply a B. Very nice work. Very excellent work. Again, we try to run. We provide 506, and there we go, one or both of the numbers are greater than the max size. If I write click and I run and I try 6.10 there we go, we get 60. If I try, for example, 103 or not, let's try 10.110 or 1010. There we go, One of these or both have an error. 200, 500, we also get an error. So as you can see, we have a way of handling invalid arguments. I'm also going to show you the following link. So you should open it up. You should have access to it somewhere somehow. It's called the built in exceptions. You can go through these to clearly understand all of the exceptions that we can create. For example, the base ones or the Args. There are exceptions. Exceptions. We will be looking deeper into exceptions when we get to the SQL part. Right now, you just need to know the surface level. Let me try and look for value error, let's see if I can find it. No error Summary. There we go. We have type error, we have value error in here. There we go. Exception raised when an operation or function receives an argument that has the right type but an inappropriate value. There we go. X and y are integers. That's good, but they have an inappropriate value. I hope you enjoy it. I hope you understood this is the link If you want to go through it or you can search built in except Python documentation. And I will see you in the next video where we are going to be talking about default parameters. So what if somebody doesn't provide a parameter at all? What would we do? We'll see in the next video. See you soon. 81. 8. Default Parameter Values: Welcome back my fellow Python programmers. In this video, we're going to be exploring default parameter values. Let's go ahead and get started. First of all, why would we need a default argument? It's an argument that assumes a default value. If a value is not provided in the function that requires an actual argument. For example, in here with the multiply x and y, as you can see, we need two arguments in here, the x, y, let's say we don't provide this. Let's say we just provide the notice that we get an error if I hover over the small highlight in here. Well, not an error, but just a big, big warning sign In here, you can see performing Cod Inan. One weak warning found and then one huge warning found when I hover over it. Parameter unfilled. If I right click and I run here. If I type in 42, 40 had entered. There we go. We get an error because missing one required positional argument y. The problem with this is that we've required the y and we just provided it with the x. In this situation, it took the x as the first argument. How do we avoid this problem? How do we avoid having errors such as these? Well, we provided it with default arguments. For example, let's say in here we have x and y. In some situations where y is not provided, I can say that y is equal to one. And notice that in here I did not add spaces. As you can see, again, we follow the P eight rules. It says 251 unexpected spaces around keyword parameter, whatever. These are called keyword parameters. We will look deeper into them later on. But for now, as you can see, y equals one, we have no errors in here at all. Now, if I provide 42.10 the answer is ten. Why is that? Well, because we've provided correct only B. We did not provide anything else which means is set to X. There is an order to this, as you can see, because Y was not provided. We set Y to one and we just multiplied by one. We can change this to two just so you can make sure that this is actually working. 40 12, boom, there we go. 24 12 was multiplied by two. We can also present default values for the x as well. In here I can say x is equal to three. Now when I write click and I run, oh wait, in here I can now provide nothing at all. So now when I write click and I run, I can type in whatever I want, 42, and then 50. And the answer will be just six because we simply multiplied three by two. Whatever you type in in here, whatever the number is, I can type, of course not that kind of number like this one. Boom, there we go. The answer will always be six. So as you can see, having default arguments is very important. Later on, we will always be having default arguments because we want to avoid these kinds of errors. But before we move on, there is a slight thing that we need to learn. And notice when we hover over multiply, what we get in here, this is called the doc strings. And we will learn more about doc strings later on. How we can display our own thing in here. The clerk equals three equals to whatever. One more thing in here. What if for some reason I wanted to have x be set as the default value? Or or having x use the default value. For example, if I provide a, I want a or Y to be set to a. How would I do that? Well, this is going to be a bit of a challenge for you. Set only the y currently. When we provide only one argument, it's being set to x and y is using the default value. Find a way to make sure that when we provide one argument, the y is the one being set and x is the one that uses the default. I recommend that you go search, you go try and find this answer yourself. But if you don't, you can have this hint in 321 specify which argument you are setting when calling the function, say y equals to the thing that you want to set, the value that you are sending. Pass the video right now and go do the challenge. Okay, welcome back. I hope you did the challenge in here. Let's see, multiply a. If I right click and I run the problem in here, that we're always going to consider that x is equal to a. So we're always going to multiply a in here by two. As you can see, we get 84. What if I wanted to multiply a by three? Meaning I wanted y to be set to a. I could simply say y equals a. And there we go. As you can see, parameter y is going to be set to a. Now, whatever a is, it will be multiplied by three because x is not provided, I'll multiply 30 by 310. Boom, there we go, we get 90. We can specify which argument we will be setting the value of. Thanks so much for watching. I hope you enjoyed. In the next video, we will be actually creating a Fibonacci function, which is a very interesting thing. We will also be learning about Fibonacci numbers. I recommend that you look them up. Thanks so much for watching, and I'll see you in a few seconds. 82. 9. Writing a Fibonacci function: Welcome back my fellow Python developers. In this video, we are going to be writing a Fibonacci function. Before actually we start writing our Fibonacci function, we need to understand what a Fibonacci function is. I'm going to follow the following link, H. Interesting choice of words. And by the way, you can simply type in Fibonacci sequence into Google and just look up Fibonacci. This is a mathematical sequence that is very popular in most mathematical fields. Or you will see the sequence almost everywhere, you might have seen it before in this form. The spiral that you see like where everybody on Instagram pretends like, wow, look at this picture. Oh my god, it follows the spiral. Yes, that is indeed the Fibonacci Nerdy sequence. The Fibonacci sequence is actually very easy. Basically what it's all about is summing up two numbers and then setting it as the third number and doing it forwards. For example, we start off with a 0.1 These are two arbitrary numbers. We just start off with 01, and then we have zero plus one equals 11, plus one equals 22, plus one equals 33, plus two equals 55 plus 38851313 A 2,121.13 34.1 and so forth. Very simple sequence. Again I recommend you can find math is fun.com. Numbers Fibonacci sequence. You can follow this link. I will make it available somewhere, but also make sure that you do some research yourself. You understand what is happening. Now you can see right here, we have the rules or the equation which this Fibonacci Sequence follows. It's very important that you go through it as well. You check out what is happening and how this works. For example, right here, let's say we want to get x at n. Let's say we want to get the number, or the Fibonacci number. And our function will be a function where we presented with the n, let's say we want the number at 11. We presented with 11, the function will return 89. How does this work? Right here, the rule is, let's say for example, you want x8xn is equal to x minus one, x seven plus x N minus two, which is x six. And that is the rule that our function is going to follow. We're going to have a small four loop inside. And we're going to be replacing things because look at what happens. First of all, we start off with 0.1 then we have the result, which is one. But then we have a change up in here, meaning that n minus two right here, n minus two becomes n minus one. The values are changing, and so on and so forth. So that is what we are going to try and implement in our program. Once we create the program, I will have a slide where we explain this further and we will see how it properly works without any further ado. Let's go back into Intellig. I will create a new Python file that I will call the fibo Naci. We'll just count Fibonacci. Fibonacci has two C's, that's why it's pronounced she. I'm not Italian, but that's what I think they would call it as in here. I'm going to define the fibo naci. Fibonacci is going to take in the end that we want to produce the number at which we want to produce the number of the Fibonacci. First of all, we need to make sure that if the end that the user is trying to provide us with is either one or zero, we want to just return the n, because right here, look at n equals zero, we have zero. At n equals one we have one. Only when we get to n equals two do we get a one. If the user inputs one or zero, we will simply return back the making our lives much simpler. We have zero less than or equal to n less than or equal to one. This basically makes sure that n is in 0-1 And keep in mind that the user will not be inputting any floats. Meaning that it's like saying if n is equal to zero or n equal to one. But it's easier to write it like this. We will return and now we need to have an else in here as well. With that out of the way, now we need to start creating the n minus one and the N minus two. I'm going to say that we have underscore minus one. Underscore minus two equal to 10. We are packing apple in here. If you're not sure what we're doing, we have the couple 1.0 and unpacking it into n minus one and n minus two. Now we're going to create a four loop. Four in range, And the range is going to be N minus one. I will tell you what this range is about, you'll try to figure it out on your own once we write the block of covets inside of this four loop, I'm going to say result is equal to n minus one or N minus two, to be more precise, plus n minus one. Then I will say n minus two is equal to n minus one. N minus one is equal to the result. Finally, we return the result that we get after going through. Let's test it out, make sure that it actually works. And then we will explain the code in here. I will print out Fibonacci at, let's say seven in here. As you can see, the result has a small warning. Glo may be referenced before assignment, okay, so it's just worried that we might not go into the fore loop or we might just return and here, don't worry. I believe that this will not cause any error at seven. Right click and run the output is 13. Let's check this number at seven. Yes, we do get 13. Let's try 13 back in the code. If I try 13, right click, run, it's 233, which is correct. What is happening in our coding here? First of all, we've said the n minus one and n minus two. These are already established. When I say n minus one, I am referencing to this number right here at N minus one. So we set it as 0.1 N minus two is zero. N minus one is one. Then we have a four range, N minus one. Now why do we have this weird range? Well, because we've already done the first two numbers, which means we don't want to go through them again. We want to continue on from there. You might be thinking, well, why is it not range N minus two? Well, because as always it's up to, but not including the last number has already been taken out, which means we only need to have a range of N minus one. And we won't even get to n minus one. We will get to n minus two. We need a range of n minus one because the first two numbers have already been dealt with with. Then what we have is result is equal to n minus two plus n minus one. Similar to what we have in here, just the numbers are in a different order, x n minus two x N minus one and x n is the result. And then what we have is n minus two is equal to n minus one. And then n minus one is equal to result. Because remember what we have in here. Let's say we're trying to get three, correct? We have n minus two, which is one. To be more precise, we have right here, we have one. N minus one is one. And the result is two, because we have one plus one. Now when we try to get n four, the result should be three. What we have is n minus two becomes n minus one. And then n minus one becomes the result that we got previously confused. I know, let's move on to the slides. How does our function work? Let's take an example and try to calculate Fibonacci at number seven. We have n minus two is equal to zero and minus one is equal to one. Right? This is how we start off. I want your full concentration right now. The result is equal to n minus two plus n minus one. We start off we have n minus 20 minus 11. This is at two, because remember we already dealt with the first two ones, that's why we dealt with zero, Dealt with one where f equals two. So right here, n minus two, N minus one, what do we have? We have the result being set as N minus one and n minus two being set as n minus one. We continue on from there, we have a three, now we have n minus two as one, N minus one as one. The result is two. We set n minus one as two, N minus two as one as n minus one, not just one as n minus one. We continue on from there, now we have the result equals to three. N minus one is set to three, N minus two is set to two, which was previously n minus 10. This is four. At five, we have the result equal to five because remember we had 3.22 plus three equals five. Again, n minus one is set as the result and minus two is set as n minus one, which is three. We do the same in here. Now we have 5.33 plus five equals eight, the result, n minus one is set to the result, and minus two is set to n minus one. Finally, Okay, this should have been six, I apologize for that. But you get the point. We have 567 and we get the result which is 13. Okay? So I know it's a bit confusing. I recommend that you go through it again. I even recommend that you try and add a breakpoint in here somewhere, maybe on the print, go through it slowly, understand how everything is working correctly. With that out of the way, I'm going to issue you a bit of a challenge. Your challenge is going to be to bring me the Fibonacci, You need to print out the first 36 Fibonacci numbers. Use only two lines of code. If you want to get a hint, you can wait for the hint. Or if you want, you can pass the video right now and go to the challenge. Use a four loop over a range and call the function with the parameter. Simply create a four loop in the body of our code. Meaning outside of our function, this four loop should go over a range of 36. At every iteration, you should print out the index that you're currently at, and use the Fibonacci with the index that is looping over. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here I will just add a print, and I will say four in range, and the range is 36. Then I will print out a Fibonacci I. That's it, because remember our function, basically what it does, you send it, it gives you the number you send it, it gives you a number. What we're doing in here is we're just sending all of the numbers from zero through to 25. Because remember 26 is not included. Right click and run, and this is the output that we get. Let me dock it to the right. So 0, 0, 1, 1, 2, 1, 3, 2, 4, 3, 5, 5, 6, 8 is are these number correct? Let me just double check. 55. Yes, it is. Eight until look at that. At 35, we have 9,227,465 So this is not easy to get on your first try. If you understood it, congratulations, that's great. I love it if you haven't, again, I recommend that you look closely at the function that we have in here. Look closely at how our function works. I recommend that you go back through the video and watch again each and every step and how it's happening. I think the explanation is pretty clear, except for this mistake that I did right here. And you can also use the debugger. This is like a homework for you. Use the debugger, rewatch the video, Understand how the Fibonacci function works, because once you get how this works, you intermediate plus level when it comes to Python. Okay. Also make sure you understand what the range is all about in here. Thank you so much for watching. I hope you enjoyed. And in the next video, we are going to be looking at function annotations and type hints. Because currently, for example, the user can, I don't know, provide us with 13.5 What would we get? We would just get an error because while object float object cannot be interpreted as an integer. We'll see how we can provide a hint to the user that please use the integer here. Don't use a float. Thanks so much for watching. See you in the next video. 83. 10. Function annotations and type hints: Welcome back to my favorite Python programmers. In this video, we are going to be looking at function annotations and type hints a subject much easier than the Fibonacci. And I know, again, I reiterate this if you're still not sure how it works, leave a comment or leaving a question anywhere that you can. And I will try to answer it as best as possible. So with that out of the way, let's now look at annotation. And tyto to annotate means to indicate to the programmer what is the type of parameter that is needed to this function. And also we can tell that programmer what is the return value of the function that we're calling. For example, in here, as I showed you when we use 13.5 and then we are using that same thing right here in the range. It just creates an error, but the user has no idea for example, or the programmer that's using your function. Because later on you'll find that it's not only you that's using functions like the Fibonacci. You can provide functions much more complicated, obviously, than the Fibonacci to other programmers to use. Just like we use, for example, the print right here. We don't know how the print is written, but we just use it. Maybe you have your own function later on in a company and then you provided to one of your colleagues. You need to indicate to the user of your function what should be provided. If you have over the Fibonacci in here, you have the end that you need to provide. So you can see that the documentation is not really clear in here on how to use the Fibonacci. What I'm going to do is I'm going to annotate to indicate that this should be an integer. And the way I do this is by adding a column and typing in. Now when the user is typing in the Fibonacci, look at that. Can you see the indication right here if I hover unfilled and you can see that the n should be an integer. Now sometimes IntellJ does this by default after you run the program several times, or if IntellJ recognizes what's happening inside of the code, it sees the N being used in a range. It immediately knows that a way, there we go, this needs to be a, an integer. But as you can see, we can unnotate like this. We can also indicate what the return type is going to be if I do the following, boom, there we go. It also indicates what the return type is going to be. As I said, this was already present before because Intelligent recognized that the return type is going to be a integer. Either way, it just flat out for us, but we can enforce it. Maybe we want some different type, who knows. But now we can know that when we're typing the code, the user is like, oh, it needs an integer. Okay, I will not use a float and I'll just strike 14. All right. Click run. Problem solved. Of course, this does not stop the user from actually typing in a float. He can do it. But as you can see, immediately they get a warning even before they run. It's expected type integer got a float instead because we specified that we want an integer not a float. It does not stop the user from actually, or your fellow programmer from actually using a float instead of an integer. But at least he will have a warning and he will use the float at his own risk. There we go. Pretty simple, nothing too much to it. For example, we can look at any function like this. If I hold down control and go to print, maybe no, this is not a good example. Let's see if we can find some function, some function where we use it. I'll think of a function in the meantime, I recommend that you check, maybe also not a good example. End also not a good example. In the meantime, I have a challenge for you to annotate. Go back to the multiplication function in one of our previous videos, in one of the older files, go to the multiplication function and annotate the two argument and tell them that it should be a float number. Indicate that the function should return a float as well. And now try to annotate the arguments and set a default value to them as well. Meaning that you need to annotate the function, set the function, or set the arguments to be flawed, but at the same time, you will need to set a default value to them. It's a small trick. You can Google it if you want. It's not that hard, but it's about the arrangement. Should you set the default value first or should you annotate the argument first? That will be the trick in here. Pause the video right now and go do the challenge. Hey, welcome back. How did you get on with that? I did actually find how you can do something like this. For example, in here, if you hover over the input and you hold down control and then Q, then Q, wait, sometimes it's not working. I hover over control, let's go. So it gives you the definition in here, and as you can see, it has the annotation that it does return a string. Now, I cannot seem to find it in here. It's not done. I don't know why. Later on, there are many examples of this. We will find one somewhere down the line. But let's go back to our multiplication in here. The multiplication in the introduction to the functions in here, we want to indicate that this should be a float, float, x y float, and the return type will be float. Now, in here, answer is equal to multiplication. If I'm typing in multiplication, what is it waiting for? However, over it, there we go, a float and float, okay? Even if I type in 2.6 for example. In here, there's no problem. When I write, click and I run, look at that, everything works fine. We get a 12, but it's just float. There we go. Now, what would we have to do in order to also set a default value? Now, some of you might have tried the following, but the ones that have actually tested things out or found it on the internet, there we go. We simply say this is how we set the default values. Now I can simply not provide anything actually, because these should be floats. We will have a 0.0 0.0 to indicate that this is a float. Now if I run multiplication, I should get an answer of two. This is how you can annotate. And at the same time, I think it's better if we just remove the spaces or does it not like that missing white space. Okay, sorry. I apologize. There we go. We do need the spaces. So ladies and gentlemen, this annotation is very important. I recommend that you always annotate, even if I don't get in the habit of annotating, because it's great habit to have in programming and your fellow programmers will love you for it. I hope you enjoyed. I'll see you in the next video where we will be printing in style. I will see you then. 84. 11. Printing with Style: Welcome back my fellow Python developers. In this video, we are going to be printing in style. So let's go ahead and get started. First of all, I'm going to provide you with a link. That link is actually a Google search and that Google search is NC color code, some called NSI or C. You can select whatever you want in here. If you go into the anti escape codes on the Github or on Wikipedia or I don't know, anywhere you want for that matter. You can see that we have certain sequences for specific colors that we can use right here. Let me scroll down until I find, for example, black foreground, color 30, bright black. You can see in here. It's takes a little bit of time to properly understand how these equal sign work. You can also go on Wikipedia and read all about how the NC codes work. But basically what we're going to do is we're going to be using them directly using the assembly that I found right here. Also we can find all the foreground colors in here, Black, white, and so on and so forth somewhere. I'm going to provide you with it. But first of all, we need to create a new Python file that we are going to call the color underscore print. These are our colors. Boom, There we go. You should find it somewhere below. Somewhere around. Basically, what we said is black is equal to this number, Red is equal to this number, and so on and so forth. We also have something other than just the colors. We can first of all, reset. We can set it to bold, we can underline, and we can reverse. How do we actually use these? Well, very simply, we print out yellow. And then I can say, hi there, Drake, how you doing red? Click and run, and look how cool that is. Now we can actually print out in yellow. That's super cool. But keep in mind that this is like dipping your pencil into a specific color. Because now if I try to print out, is this still yellow? If I try to print this out, you'll see that it stays yellow. That is because as I told you, it's like dipping your brush into the color, and then you always paint with the same color. But if we want to stop it, what can we do? Well, we can use the Reset, for example, in here I can say reset on boom, there we go. It's simply resets. Or even better, you can use the Reset immediately on here. Boom. Look at that. And now it just does this following line in yellow and it resets everything else. Let's try a few other things. We can also stack them on top of each other. For example, in here I can add bold. Now when I write Click and I run, it's yellow and it's bald. If I duplicate, are we still okay? In here I will also underline, look at that now, bald, underlined, and yellow. Finally, I can also print out reverse. This is getting out of hand book. Look at that. It's reversed, bold yellow, and underlined. I can, for example, change the color so I can change it back to. Maybe can. Okay, there we go. We've used a single quotation mark. We'll make it into a special character. Right click and run. And there we go. As you can see, this is how we use our colors. It's not very hard. I'm going to, for one last time, show you something that's interesting. First of all, I will print out and just reverse everything from here on out. We should have everything normal, let's just check right click and does not work like that. We need to actually apply the reverse. We should do the reset. Reset. Let's check. Okay, there we go. So the reset does work, and notice that it creates an empty space. That's why we also have a small space in here because we need to accommodate for the extra variable or the extra argument that we provided in here. For example, what I can do is the following. I can add a replacement field and then that format. And then I can provide it with manita for magnetat, how you call it, right click. And you can use a replacement field in here. In this situation, using the replacement field allows you to just have no spaces behind it. Obviously, we don't need to use the format, we can simply use magneta like this run and there we go, it works. I hope you enjoy it. I hope you understood how this works before we move on. A small function that you need to create in order to tie into the main theme that we're working in this section. Create a function called print with color. It should take two string arguments, the text and the effect that you would like to have, and use replacement fields to create a string with the color, then reset the color and print out the string. Basically, the goal of this function is to send in some text, send in the effect. And for that effect to only be applied to the sentence that we want to print out. Meaning that we don't want any other sentence to be affected, only this one. And I already showed you how you can do this. Pass the video right now and go to the challenge. Okay, welcome back. How did you get on with that? Right here at the top. I'm going to print or define my print with color. It will take two arguments. The first one is the text, which is going to be an SDR, stands for string, and the effect which is also going to be an SDR. And it will return non, meaning nothing in here. To do two dots again. The column, I'm going to have the output underscore string and it will be equal to the following. I'm going to first of all have replacement field for the effect, we start off with the effect. And then a replacement field for the text, and finally a replacement field with reset inside of it. And then we will print out the output string. So the whole challenge was in providing this reset, because we apply the effect we apply to the text and then we actually reset it. And then we print out the string because we don't really want anything printed out now in here, I can, for example, let's say I want to print with color. Hi there, Mr. Crowley. There we go. I don't know. Crowley. Crowley. Okay. Anyway, Mr. Poppin. I don't know. And then we had a comma, and then we want it to be bold, just an effect. And then in here, I will print out I still bold when I right click and I run look at that. Hi there, Mr. Poppin. I am still bold. And this is because we've actually let me add a reset in here, so we can clearly see what's happening. Boom, there we go. So it's only applied to poppins. Now, if you want, we could have gone even the extra mile of adding a reset right behind it. Now whatever we had previously will not be applied. So now we can remove the reset from here. And I'll right click and run. There we go. We can see that it only prints out with color with the exact effect that we want in here. I can change this to print with color. Maybe the function name is not really good because print with color seems like you can only print with color. But we can print, for example, with an underline right click run. And there we go. I hope you enjoy it. I think this is a fun program or a section or lesson in this section. I hope you enjoyed in the last video and probably the last one. Maybe we'll add more later on. But for now, the last one is going to be the star arcs. And we're going to learn all about that and how we can provide multiple arguments to a function or as many as we want. I will see you then. 85. 12. Star args: Welcome back to my favorite Python programmers, and in this video, we're going to be learning about the star Args. Let's see, first of all, what it does and realize that we've already used it a lot of times before. Even in this video right here in the color print, if you've noticed right here, we were using yellow. And then hi there, Drake. What you're doing? Bold. And is there anything yellow or whatever? We sometimes even added a reset in here and we could also even add, let's say red for example. As you can see, we can add many of these arguments. So now when I write click and I run, look at what happens. We reset and then we make it red and then there's an underline and so on and so forth. Print, just like the print with color is a function. But notice that the print with color can only be provided with two. If I try to add a comma and say red or reset or whatever, look at what happens. I get an error if I have not an error, just a very serious warning where I hover over it. It tells me that unexpected argument we're providing more than the arguments that we've said there should be. We just said we need the text and the effect. But in here, for some reason we have more than that and it's totally normal. How is this working? Well, if I hold down control and I go to the print function, you'll see that we have something very special in here called the star arcs. I will explain what the self is later on when we start learning about object oriented programming. As you can see, there is the star arcs. There is also the separator. I'm not sure if we've used before. I forget honestly the end and the file. And we'll see the file also in one of the upcoming sections where we have input outputs of files. But for now, the most important part is the Star Arcs. What is the stars? Let's go back into our slides and explain what are star orgs? So first of all, star orgs are a special parameter that allows you to pass a variable number of arguments to a function. Keep in mind a variable number of arguments, meaning one argument, 23172100. When you use the star arc, all of the arguments passed to the function are packed into a topple. We'll see what that means later on. But something to keep in mind, if they're packed into a topple, it means that we can unpack them if we want or we can iterate over them. You can access the arguments in the topple by iterating over the star or variable name. The star arc can be used to make your function more flexible and reusable, just like the print function where we can make it more flexible if we want to print out one word or ten words, or five sentences, or one sentence for that matter. Or maybe we want to add some effects and so on and so forth. The star arcs are very important. They are very useful. Let's look at a way of using them. I'm going to go back into my code in here and create a new Python file that's going to be called the car. Hit enter. Now in here I'm going to define fruit, underscore function. I'm going to have the, by the way, it doesn't have to be actually stars. We can call it star fruits, we can call it star, Michael. We can call it whatever we want, but it's the conventional name of calling it stars. And in here we're going to say four arg stands for argument. In args, I'm going to print out the arc. Then in here in the body of my code, the fruit function. I'm going to have apple, banana, cherry. Now if I write Click and I run look at that apple, banana, cherry, I could add a comment and say pineapple. There we go. We just prints out pineapple that easily. Again, as I said in here, we could have called this the fruits. Now in here we would fruits. This would be the fruit. There we go. It would work exactly the same, but it's better to call it or it's the conventional way and will help other developers read your code properly. Okay, if somebody sees star fruits, they're like, what are you doing? I can't you just use orgs like a normal person. In this situation, maybe it's better to have it as fruit, but I just called it be. You have the or, which are the arguments. And then you have the g, which is a argument if you want to extract information from it. Before we move on, this is just a very simple lesson just so you know the possibilities that we have. But I want to also print out the type of G. I also want to print out this is the Args. Then I will use a replacement field for the Args. Duplicate this, I'll say the or, whatever. This is the star. Star Args. When I write, click and I run, this is what we get. First of all, the Args in itself is just a topple right here. You can see that the type of is, if we try to print out as we've seen before, we know it's apple because of the parentheses that we have around it. But if we check the star args, you'll see that it's been unpacked. We have them printed out, unpacked. That's basically it. There's nothing too much in here. I recommend you go through this again if you need more information, more examples. But I honestly think that's enough. We will see real world examples of using the star args later on in our sections. But for now I have a bit of eight challenge for you. And your challenge is to sum up the squares. Create a function that takes any number of integers. The function should calculate and return the sum of the squares of all the arguments. As an example, let's say we have this function is called, or I call it the sum of squares. Then we provided with 1234. And the return value should be one to the power 22 to 23 to the power 24 to the power two equals 30, and we simply return 30. Pass the video right now and go do the challenge. Okay, welcome back. So in here I will create a new Python file. So going to file new and I'm going to call this the sum of squares. Enter in here I'm going to define the sum of squares, star args and then we will have the square underscore sum equal zero and then four R. I will go through, say, wait, I will say that the square underscore sum is plus equals to the arc times times two. This might be the part of the challenge that you forgot how to make it square, or to the power of any number for that matter. Then finally, when we go through everything, we will return the square sum in here. I'm going to say that the returned underscore sum is equal to sum of squares, and I will fight that. 1234 56k 54. And then we will print out the returned sum. I will also have another return sum which is equal to the sum of squares, and it will be 12.3 This is just to demonstrate that we can provide any number of arguments that we want. So that when we write Click and we run, this is what we get. I'm going to add maybe ten in here just for the fun of it. Look how dynamic and flexible our functions have become with the star arcs. I hope you enjoyed. I believe we are at the end of this section. As I said, maybe we will upgrade this. We are going to always be constantly updating the course, so you'll be always able to go back to it and check it out. But for now, I think this is the end of section number six. Congratulations on making it to the end. You now know more than 97% of the world's population in Python. And this is something to be proud of, definitely. The next section we are going to be looking at object oriented programming in Python, which will really expand the horizon of knowledge that, you know, I can't wait to see you there and I'll see you in there. Well, I don't know when you want to continue. I wanted to say like in a few seconds, but who knows? Maybe you want to continue on in a week. You want to take a break? You deserve it. I will see you. 86. Section 7 - Object Oriented Programing | 1. OOP 101: Welcome back my favorite Python developers to a brand new video and a brand new section where we are going to be learning the most exciting part of all of programming, not just Python, which is object oriented programming with classes. I'm very excited to teach you this because once you know object oriented programming, you have officially expanded your horizon of understanding. Once you understand and fully comprehend object oriented programming, there is no language in the world that you cannot learn in a matter of two weeks. It will just be a matter of understanding the syntaxes around certain languages, for example, Java or C plus plus or I don't know, whatever you go to learn. If you know object oriented programming, that's it. You are golden forever. So I want your full concentration, your full attention. I will try to explain everything as deeply as possible, but it also requires attention from you. So let's go ahead and get started. What is Oop? Oop stands for object oriented programming. It is a programming model that uses objects and their interactions to design applications. We will expand on that idea later on. It is a way to, of organizing and structuring code that focuses on the objects in the program rather than just the functions and procedures. So up until now, everything that we were working on were variables that we would apply to functions that we would use certain operations on. But now we have a more organized, more structured approach to the objects that we are going to be using. Almost everything is Python is an object with its properties and methods. Every single time we would create an integer, it would be an object every single time we create a list, a string, a topple. These were all objects that have been created, and you'll see what I mean when we start actually creating our own classes and objects in Python. Object oriented programming is supported by several features such as classes, objects, inheritance attributes, et cetera, et cetera. And we will see all of these. Let's now look at a class structure. A class is like a blueprint of how the objects should look like and what they can do, and the objects are instances of that set class. If you've ever been building a building, that sounded, if you ever construct a building, if you ever have a certain project that you need to create, you need to create a blueprint of that project that then you give to the engineer, and the engineer follows that blueprint, and then he can add and change and maybe expand on it. There is a certain blueprint that the engineer needs to follow. The same thing holds true with the class. The class is a blueprint of what the object should look like. You don't have to use every single thing an object has to offer. You don't have to use every single thing that the class has to offer. But you need to adhere to certain rules that this class or blueprint provides you with. Every object that you create from that class is called an instance of a class. This is the class structure that we would see. First of all, we have the keyword. This keyword is used to define a new class. Just like we have the DEF de, when we start creating a function, class is used to create a new class. Then we have the class name. The name of the class. And this starts with an upper case letter. You've seen that when we're creating variables, we need a lower case letter. When we're creating functions, we start with the lower case. When we're creating final names, we start with a lower case. Only when creating a class do we start with an upper case. This is what differentiates a class from everything else, and I recommend that you follow these eight rules. Next we have the class object that we created at the bottom, which is equal to the class name with parentheses. And we'll see later on how we can assign certain variables that will be assigned to attributes inside of the class. Obviously inside of the class, we have the constructor, we have attributes, we have methods, we have a lot of things. Without any further ado, let's go back into Intelligent and start working on our classes. File new and new project. Once we hit New project. Yes, Python, We're going to call this object oriented programming. And I will copy this. It's in the Python course. Object oriented programming. Yes, finish and this window. Okay, there we go. Now we have a new project. I hope you have it up and running. As I always say, your UI might be different based on the new intelligent that comes out, but 99% of the things should be the same. Let's go ahead and create a new Python file. Let's click on this right here, a new Python file. And I will call this, oop, oop, Underscore Intro Okay, we're back from the freeze. I will close down the project and I will start creating my class. The class is we'll start off with the keyword. I will call it new class. And the new class will have simply x equals 23. And with spaces around, just like with functions, we need to leave out two spaces between the class and the main code of our body, or the main body of our code, I think. Okay, the main body of our code. In here, I'm going to say we have the object new class and it's equal to the new class. There we go, I will simply print out object, new class x. Notice in here we did not provide the object new class with an x. We did not set it as anything. We just said that object, new class is equal to a new class. This is the instance of the new class and it's an object. Notice now if I write click and I run, I get 23 because the new class inside of it has this property or attribute. Later on we will see the names of these small detailed things, has x equals 23. When we create an instance of that class, it immediately receives that property right here. Object of a class has something inside of it that's called, that we can actually check out and see. This is the structure that we were talking about. This is the model, this is the blueprint upon which we will start building everything going for. But obviously, this is not a real practical example, like having a class that has x equals 23 only is not really something that's, as I said, viable or practical. We're going to look at a deeper example. But before we do that, we need to learn something called the constructor. Which is the underscore, underscore in it, underscore, underscore, and then self inside. This is a constructor method which allows us to construct objects. For example, right now with our new class, we were forced to have x equals 23. But what if we wanted to have x be different for every single object that we create? We would use a constructor. It's a special method that is automatically called when an object of the class is created. When you create a new class, the underscore, underscore in it. When you create an object of a class or an instance of a class, what I mean by that is when you actually say object, new class equal to a new class, you're creating a object. When you create an object, this method is automatically called. It is used to initialize the objects attributes. And we'll see what those are in just a few. But for example, x equals 23 is an attribute. The self parameter is a reference to the object being created. So the self references the actual object that we have. And additional arguments can be added as needed, depending on the attributes that the class should have. So we'll see if we have two attributes, we will need two arguments. That's not necessarily the rule here. We'll see that there are different scenarios for this case. But yes arguments are sent to certain attributes that we have. Finally, it's a convenient way to ensure that all objects of a class have a consistent initial state. And I will tell you what that means in just a bit. But just know that this is the constructor. It's very important. And the other very important lesson is that the self references the object that was created. Let's go look at an example of that here, I'm going to comment all of this out. Hey, welcome back. So don't you just love when you have a very well working program and then it insists that you update it, and then when you update it, it keeps freezing every couple of minutes. Uh, uh, about that. I love it. That's why I never like to update anything. That's why I still use Python 3.9 even though there are updates, just like I found a stable Python that works, that's it. I don't want to upgrade to anything. As long as obviously what I'm teaching you right now holds true. In the future, I'm going to create a new class. And I commented everything out by selecting all of it and hitting control forward in here. I'm going to have class person in here. I'm going to define the int. I always recommend that you use the autocomplete the tab to autocomplete all of that. Just like we said before, this is a method we need to use the def t in here. I'm going to add and we'll have ph now. I'm going to have self name. Equal to name and self h equal to h as you can see in here, The self, as I told you before, self is the parameter that references the object itself. Which means that when I say, for example, in here, underscore Michael, and this should be underscore, not stands for person, underscore Michael equals person. Open up the parentheses and send in Michael with the age of 27. When in here, self means underscore Michael, and we've provided it with the name, which is Michael and age which is 27. Now you might be thinking, where's the self? Shouldn't it be right here? Well, the self is taken from the underscore Michael that now when we mention underscore Michael, we know that its name is name and its age is that we've sent before. That's basically it. This is the constructor. It allows us to construct a method just to show you that it's called automatically. When an object is created, I will print out a new person just created. When I write click and I run, look at that. A new person was created in here as well. I'm going to print out, print out underscore Michael. Do name underscore Michael. Right click and run And look at that Michael And 27. I hope you understood what is happening in here. I know at first sight it's like whoa. Oh, everything is new. Everything is weird. But don't worry about it as we take more example, as we do challenges, as we progress throughout the course, it will become easier and easier. So with that out of the way now your challenge is going to be to create a new object. So create a new object from the class person. That person should have a name and an age. Of course, make it different than the one that you currently have. Print both out on separate lines, the name and the H. And that's basically it. Now, once you do the challenge, you will fully appreciate the power of having classes. So pose a video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here, underscore someone will be equal to person and that person will be someone with the age of 42. So if I print out underscore Michael name, sorry, underscore someone, name, duplicate this age. When I write, Click and I run, look at that, another new person was created. Look at that, the constructor was called and then we have someone. And 42, I will comment this out for now. And I will just have it like this because now that we've established that this works, it will work. As you can see, classes are very important. It's a blueprint, a structure of a object, and how it should work. Every object has its own name, has its own age, has they share the same attributes? But each object has different values for those attributes. So I hope you enjoy it. I hope you're not too confused. In the next video, we will look, or we will take a deeper look, into classes, instances, and so on and so forth. So thanks so much for watching, and I'll see you in a few seconds. 87. 2. Deeper Into Class: Welcome back my favorite Python programmers to a brand new video. And in this one, we are going to be delving a little bit deeper into classes. Understanding instances, constructors, the self, and more in Python. As I told you before, every type is a class. This is something that you need to keep in mind as we go forward. Back in the person in here, I'm going to create another method that I'm going to call deaf. My underscore height. The height as you can see, as soon as I type in the left hand bracket, you'll see that the self gets autocompleted. I'm going to provide it with another argument which is going to be of type. I'm going to print out the following. I'm going to say replacement field, I'm going to have name is replacement field self height. Or we can actually we have to use height directly. And I'll tell you why just a bit centimeters all unless you are in the Imperial System. Again, we need more place in here now. I'll just keep person for now in here, what I'm going to do is I will add a print and then I will say underscore Michael height, height. Now I can provide it with 172. I'm not sure if that's my height, honestly. Maybe it's more, they tell me it's definitely more Pero, I've never measured it. Anyways, right now, we can call a method on an instance. Python provides the self automatically, but you can provide it yourself if you want. For example, we can do the following, person height and then provide someone. And then 188, for example. When we say underscore Michael might, just like with the constructor, the self is the underscore Michael and 172 is set to my height. Now if I write, click and I run, Boom. There we go. Michael is 172, centimeter stall, someone is 188. You can see clearly how myself or my Let me talk this right here so we can see everything fully. You can see how someone is self and set the 188 centimeter. Pretty simple. Nothing too much in here. Now I'm going to issue you a bit of a challenge to add another method. Create a method inside of our class that prints out the person's weight. It should have an integer argument, that is the weight. And add the way to one of our person objects and display it properly. Pause the video right now and go do the challenge. Welcome back. I hope you tried your best. It's pretty simple. Just like we had my height, we're going to have underscore weight. Oh my God, I cannot weight. Is that how we write weight? I don't know, weight, self weight. And I will print out, boom, what's the problem in here? Method? My weight may be static. Okay, we'll see what they want Later on in here, I will have a replacement field and self name is replacement field weight, 100 kilograms KG. Okay. So down here again, I'm going to add underscore Michael my weight and I'm also not sure. I think it's 72 as well. Okay. And I will just add a print so that we can separate Michael from someone. Right click, run, and there we go. Michael is 72 K's Now let's go back right here to my weight and my height. You'll notice that when I tried to use an attribute which is right here, this is one of our attributes on the name, as the dot name. And by the way, I didn't need to name it name. I could have named it name of person, you know, I could have called it whatever I wanted. But it's a convenient way of calling the attributes the same as the arguments that are being sent. So this is the attribute name, and this is the argument that's setting, or that's the value that's being given to the attribute. And we usually name the attributes the same as the arguments that are being given to us. You'll see it a lot in examples of creating classes later on. But you can name it whatever you want. Now notice in here we were able to use self dot name, for example, when we said underscore Michael height. I called my height but the self was Michael. Self name. It looked for the name attribute of the self. Wasp underscore Michael, it found the name was Michael. That's how we were able to print out Michael here. That's why we were able to print out someone here is height. Now notice on the height, we don't have the self dot height. That is because we have height not as an art attribute but just as an argument inside of my height function. It's not an attribute. Everything that's in here is an attribute. Everything that's self dot is an attribute. We will look deeper into attributes in the next video, but you have to know the following rules. Before we finish off, I want to show you another way that we can set my weight. I'm going to scroll down in here and I'm going to say underscore someone weight. You'll see that I can add a weight. I'll just add 42. Now that's too low. 142, someone is getting out of shape. Right click and run. And there we go, 142 kilograms. But now look at what I can do in here. I can say underscore someone weight is equal to 100. What is happening in here? If I print out, I can say a placement field in here. I'm going to say someone name has a change of weight. Now the mouth now they are replacement field, someone weight. Interesting. Where did that come from? How are we able to access weight even though we don't have anything in here? When I write, Click and I run, look at that. Someone has a change of weight now. They are 100 weird. Let's try this on Michael. Let's see if I try to print out underscore Michael weight. I get an error even though in here someone does have weight. Right click and run. Person object has no attribute. We wait, wait, wait. But someone has weight. How is that possible? Well, as you can see, if we try to force an attribute onto an instance of a certain class, an attribute gets created, but only for that said instance. For example, for the underscore Michael weight, there is no attribute weight. We haven't created one. There's no weight in the actual class. But for P someone, when we said underscore someone, that weight a weight was actually created. This shows the flexibility of Python that allows you to actually create an attribute from inside the body of your code. I know this might be a little bit confusing, but later on you will see how it's just like everything that we learned in Python. It might be confusing at first, it might be like this doesn't make sense. But later on with more and more examples, it will be more. So I hope you enjoyed it. I hope you understood what is happening in here, even though it's a bit confusing. In the next video, we are going to look deeper into class attributes and maybe get a better idea of what's happening. Thanks so much for watching CUNFU. 88. 3. Deeper into class attribute: Welcome back my fellow Python developers. In this video, we are going to take a deeper look into class. Attributes are classes, or I mean what are attributes really? Attributes are variables that hold the state or data of an object, just like we have the name and the age. Those are states and data about the objects that we're creating. They are also known as fields or properties, and they are defined within a class. If you ever see somebody refer to attributes as fields or properties, don't get scared, just know that they can be used. They can have different names. An attribute can be any type of variable, even another object of a different class as we've seen. We can have strings, integers like the name and the H, but the type of the attribute could also be from a different class entirely. When Python attributes are defined within the constructor method, which is the in it, and attributes can be accessed and modified directly using the notation, just like we saw when we were modifying the weight of the person. And we'll delve deeper into that later on. But back to the line where we printed out the weight in here where we had print Michael weight. It shows the dynamic nature of Python that allows you having two instances of the same class, but that end up having different attributes. So let's go ahead and now create a different type of attribute that we haven't seen yet, which is a class level attribute at the top right here, just under person, I'm going to create a variable which is the number. Let me just make the smaller I feel clustrophobic. The number underscore of limbs and I will set it as four. This is called a class level attribute. Class level attribute number of limbs. Four, right? We have four limbs, two legs, two hands, whatever. Every single person has these four limbs. Let's go ahead and print all of that out. I'm going to comment this for now. I will just have an empty print in here. I'm going to print out the following replacement field. I will have persons name. Okay, has replacement field. What's the problem in here? Has replacement field and then person number of limps. I will duplicate this to change right here, underscore Michael, Michael. Duplicate this. Someone, someone, Okay. If I right click and I run look at the output that I get. First of all, at the bottom in here I have some weird thing because I did not say name on Michael and someone, and this should be better. There we go. So as you can see, a class attribute means that all the instances and even the class has that attribute. So person underscore, underscore name returns the actual name of the class. You can even go to the documentations to make sure that that is exactly what it does. Because remember, person as a class doesn't have a name, doesn't have the attribute name. It's given to the instances through the constructor. Michael has the name, someone has the name, and all of them have the number of limbs. Because it's a class level attribute, it's not specific to any instance, it's to the class level attribute. But we can also change the class attribute in here. I'm going to do the following. I'm going to just have a simple print. And then we will print out changing into, when we change into an octopus, I will say person number of limbs is now equal to eight. I will copy the code and I will paste it in here. Now if I write Click and I run, look at what I get. I'm changing into an octopus access per number of limbs. And I change it to eight. As you can see when play and go around with the class level attribute, I actually can change it for everyone. What if I changed this person number of limbs? What if I changed the class level attribute? Not directly on the class notes. Right here, I accessed person number of limbs. What if I did it to a specific instance or object of that class? Well, you're going to find out in just a bit because you have a challenge to change the class level. So you'll need to change the number of limbs, but this time only to one of our instances, either to Michael or to someone. Afterwards. Print out the number of limbs for the other persons. Print it out, just like we've done always for person class, for Michael and for someone. Are there any changes? And what does that mean? Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? I'm going to copy these lines. Put them in here from octopus, changing into an insect. And we're going to have in here six. And I'm going to actually say changing Michael into an insect. And underscore Michael has the number of limbs changed. We haven't changed it for the actual class, we simply changed it for an instance. What do you think is going to happen if you haven't weren't able to do the challenge for some reason? What do you think is going to happen now? Will the number of limbs change for everyone or will it just change for P? Underscore Michael, If I write Click and I run changing into an octopus, we changed it on the person everyone changed. But now when I'm changing it on Michael, underscore Michael number of limbs, you'll see that person stays eight. Someone says stays eight, but Michael has six limbs. Now, as you can see, when we change a class level attribute for a specific instance, only that instance is affected, the other instances, and even the class stays the same. When we change it on a class, it changes for everyone. Again, we're delving deeper and deeper into things. In the next video, there is something that we will have to watch out for, that I will tell you about. But for now, I hope you're understanding what's happening. I hope you're enjoying. If you have any questions, leave them wherever you can. Ask me wherever I'm available or the instructor, that's you and I will see you in the next video where again, I told you we're going to see something that we need to watch out for. Thanks so much for watching See you and a few. 89. 4. Something To Watch Out For (__dict__): Welcome back my fellow Python programmers. In this video, we're going to look at something we need to watch out for when developing our classes and working with attributes. Also looking at that thing that we need to watch out for with the underscore. Underscore, underscore, underscore. What is the underscore, underscore, dict? Underscore, underscore. Okay, I'm going to stop. Attribute is a dictionary that holds the attributes of an object. Now, we have not yet looked into dictionaries, but we will definitely be looking at them later on. But for now, it just is a key value pair. The dictionary is a key value pair. And I'm going to explain more when you actually see the output. So it allows you to access and manipulate an object's attributes as if they were items in a dictionary. Again, don't be freaked out by the words dictionary. We are going to be looking extensively at dictionaries, but it's very important that we look at the underscore, underscore dict right now before we move on. Because we need to understand what's happening under the hood of our workings. It's created automatically when an object is created and it contains a key value pair for each attribute of the object. Where the key is the attribute name and the value is the attribute value. All that you need to know for now about the dictionary is that it's a key value pair list, sort of, Okay, let's see it in action. And I will tell you what the keys are, what the values are, and what the dictionary is. If we go back into our code in here, I'm going to actually comment all of this out for now, boom. And then right here, where it, where is it? Where I have name. And then two, let's see, where we add weight. We have someone weight. Okay. I think in here it's a good place to, for example, print it out. I'm going to print out underscore Michael, underscore underscore dict. And I will duplicate this line and use someone underscore underscore dict. If I right click and I run, let's look at the output that we get. As you can see, as I promised you, these are key value pairs. It's a list of key value pairs. The key is this right here on the left hand side of the column. And it's the key which is the name of our attribute, the name. Then we have the value of that attribute, which is Michael. Then we have another key pair, which is the H. This is the key, this is the value. Again, don't worry too much about what's going on in here. Once we learn dictionaries, it will become much, much easier. The only thing that you do need to worry about is look at what we have in here. On Michael, we have the name and age, correct? Pretty simple, pretty self explanatory. Nothing too much in here, but if you look on someone, you have name, age, and then wait. Hmm. Where did that weight come from? Well, if you remember, when we were working with Michael and someone on someone, we had this line of code on line 34 where we actually added weight equals 100. And what happened when we did that? We were able to access the attribute, but when we tried to print it out for Michael, look at that, there was an error. Remember that is because of the flexibility of Python. We've already talked about it. When we had someone weight equals 100, the attribute was actually created. And you can look at all of the attributes using the underscore underscore dict. Again, I recommend that you open up the documentation right here. There we go. Python standard library. Everything is available there. You can look for the documentation of control. Underscore underscore ****. And for some reason it's not available. Let's try **** mapping type, Let's click on there. Okay. No, it's just talking about the dictionaries. You can type in underscore, underscore, underscore, Underscore. In Python, you can find all resources delving much, much deeper. But basically, it represents a dictionary or any mapping object that is used to store attributes in an object. There we go. That's everything that you need to know about the dictionary. It shows you all of the attributes that you've created so far for your objects. Thank you so much for watching. I hope you enjoyed this was just to show you how we can create attributes out of thin air and very, very flexibly. In the next video, we are going to be delving deeper into methods on our classes. So I'm excited to see you there. See you in a few. 90. 5. Deeper Into Methods: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be delving deeper into methods. But before that I want to tell you about something very important. That is the doc strings, for example, in the print. If I hover over the print, I don't know if it will give me too much information. But there we go, You can see it gives me the values that I have to give it. It gives me the various types that should be given to it and it's return type. But right here you'll see that we have this description of the actual method. So it prints the values to a stream or to the system, dot out whatever. By default, optional keyword arguments ya. So it gives you information about what this actually does. What if we wanted to have the same thing for the person in here? Just calls the base class of the class when called exceptional arguments, whatever. So it's not really descriptive of what the person is or what we need to provide it with. Instead, we can create something called a dog string. Basically the dog string are what's called three quotation marks right here and we start typing in this is the person class, provide it with a name, a H. And you can use two methods, underscore height and my underscore weight. That's a very basic doc string. Obviously, later on I'm going to show you, oh my god, how many mistakes that I make. Anyway, I'm going to show you a more extensive way of creating doc strings with better looking attributes display and better method display. But for now, if I hover over the person, look at what it gives me. This is a Person class provided with a name and age and you can use two methods, my height and my weight. We've actually added a bit of description to what this. I can also add description to methods. For example, in actually strings for example in here prints out the name and the height provided actually doesn't actually set the attribute height. For example, now if I hover over my height, there we go, prints out the name of the height provided doesn't actually get attribute height. Okay, so that is the dock string. From now on, I'm going to try to use it as much as possible. So the doc string is a string that appears at the top of the class, or a function, or a method. And it's used to provide documentation or information about the code that you are going to be using or any other programmer that takes over your code is going to be using. But for now, let's go deeper into method and the first thing that I'm going to do is create a new Python file and call it the Bitcoin underscore wallet. Once we have that, I'm going to create a class, call it the Bitcoin wallets. And I will add a dog string in here and it will be wallet to hold your Bitcoin in. There we go. Then I'm going to define the in it. It will have a seed. Oh my God. It will have a seed. Underscore name and the balance. Then in here I'm going to do name equal self balance equals balance. I'm going to create a method that will allow us to deposit. Define the deposit. Open this up and we're going to have the amount underscore two, underscore add. Then we're going to very important, we're going to the to add is greater than zero, then we're going to self balance plus equal the amount to add. Then we'll define the withdraw. The amount to subtract. Subtract, Is it written incorrectly? Subtract. Oh my god. Subtract the amount and withdraw. What's the matter with you? Withdraw may be static. Okay, this warning always up. It will be resolved once we actually finish typing everything. We want to make sure that the attract greater than zero but still less than the self balance because we need to make sure that the amount that we want to subtract is actually available. And here we need to add the column, and then we're going to say self balance minus equals the amount to subtract. Last but not least, we're going to have the show balance. This will not take any argument and simply print total amount of BDC replacement field self balance. There we go. If you're still not with me on the same level in here, take your time, pause the video, write everything out, make sure you understand what is happening. These are very simple methods. In a very simple class, we simply have the name that are two attributes, the name and the balance. We have three methods. The first method where we deposit and we provide the amount to add. We make sure that the amount to add is greater than zero and plus equals to the attribute balance withdraw is the same, the amount to subtract. And then we make sure that the amount to subtract is less than the total balance, but greater than zero and minus equals the amount to subtract. And the final one is simply a definition that allows us to show the balance. Let's go ahead and create here. I'm going to create wallet underscore Michael. As always, you don't have to create Michael. You can create your own wallet, whatever your name is on the other side. Create the wallet in your name, it's just going to be called Michael. Now some of you that know a lot about Bitcoin know that the seed name or seed phrase shouldn't be that small. But just for the purposes of this example, we're going to have 100 Bitcoin. Some of you are like yes, 100 Bitcoins. And obviously we don't have a cap on the 100 million. Let's not worry about that for now. Let's just work on using, I just thought it would be a good example to have a wallet. All the examples that you find on the Internet are always like bank account and balance and whatever. Let's do something more fun. Let's not be centralized now that we've created our Bitcoin wallet with the seed named Michael NA balance or initial balance of 100. I'm going to get Michael wallet and show the balance when I write Click and I run, there we go, Total amount of BTC is 100. Now I'm going to do something else. I'm going to get the wallet of Michael deposit and I will deposit 122. Then I am going to duplicate this line again. Hold down Shift Alt and move it below. Now when I write, click and run, there we go. Look at that. They were added to each other. Let me copy these past them in here. Add an extra space and withdraw instead of add and withdraw 30. Now when I write, click on, boom, there we go. 192 for example. If I try to withdraw -130 look at that, it doesn't work. We simply print out the show balance. As you can see, everything works exactly as we need it. Though there is a slight problem. Obviously there are still a lot of problems in here. But the main one that we want to fix right now is that every single time we make a change, we actually have to call the show balance every time. I mean, it's very cumbersome. Let's say we make like hundreds of deposits and hundreds of transactions. We just have to make sure that we always show the balance very good, not very efficient use of our time. So a better use of our time is giving you a challenge. And your challenge, Oh my God. And your challenge is going to be all about transparency. So print out the balance every time we make a withdrawal or we add money to our wallet, and that's basically it. So you need to find a way to show your balance every single time you make a withdrawal or you add money. So pass the video right now and go do the challenge. Okay, welcome back. This is something new. We've never actually use the self to call a method that is within the class, but it's very simple right here on the deposit, after we add some money, we're going to say self show balance. We are obviously going to do the same in here. We will only show balance when we actually do make a withdrawal or when we do actually make a deposit. In here, I no longer require these lines. There we go. Every single time we make a deposit or a withdrawal, we should get this printed out to us. For example, in here, if I add or I remove 32, I should get 190 at the end. Everything works fine. Everything works good. As you can see, we can call methods within other methods that are in our class. I hope you enjoy it. In the next video, we're going to be looking at the warnings that we keep getting, telling us that we might have a static method. Well, in the next video, we are going to be looking at static methods and create our own deliberately, so can't wait to see you there. I see you, I will see you in a few seconds. 91. 6. Static Methods: Welcome back my favorite Python developers to a brand new video. In this one, we're going to be learning about static methods. What we want our static methods to do is we want them to keep track of all the transactions happening. We will need a way to keep track of the times and the dates that we want. I'm going to go back to the slide later on. For now, let's go back into our code and let's set things up. First of all, in order to use the time and the date, we need to import two important libraries. We will need to import the date, time, and we'll need to import PY tz. Don't worry, you're going to see some freak code right now, but don't get too frustrated or anxious about it. The code will be explained and will be self evident once it's working. Now for some of you the YZ might not be very apparent. You need to right click. And in show context, you should see somewhere in here where it tells you to install or download or whatever. Just click on that. If it doesn't work immediately, close down intelligent, open it back up. You should be able to download or install PYTZ. No. The next thing we want to do is whenever we create a new Bitcoin wallet, we want to create a list of transactions. So self dot transaction transaction Z list. This will be a list of all of the transactions, whether they are depositing or removing or withdrawing, I mean a list of transactions. And notice we don't really need to give it any argument. We just can set it as an empty list just to initialize it. Now, the next thing is whenever we make a deposit, we need to provide it with the following information in the deposit. After we show the balance, we want to do the following or actually as a rule of thumb, it's better to do it in here before we actually show the balance. I'm going to do self transaction list append. I'm simply appending it and now look at what's going to happen. Again, I told you, don't freak out. I will open up the parentheses and write pytZuTc localize. Then open it up again. I'm still inside of the localized daytime daytime UTC. Now, scary. I know. Then come on the amount to add what is happening in here. Unexpected argument. All right? What is the issue? This one is closed, This one is closed as well. Okay. I think in here an extra one and then in here I have to. Okay. There we go. Okay. Okay. Okay. So this one is in here. So we're providing where appending our transaction lists with a couple, and that couple has two elements. The first element is going to be the time and the second element is going to be the date. Let's go ahead and test this one out. I'm going to create a method in here that's going to show all of our transactions. So I'm going to define show underscore transaction and then I'm going to say four date amount in self transaction list. The amount if it's greater than if amount is greater than zero. I'm going to set the trans underscore type to be equal to deposit else we're going to set the transaction type to be equal to withdraw. I'm going to do amount multiplied equal minus one. Again, this will make sense later on, but for now we just have to do it. You have to trust me. Then finally in here, I'm going to say that I want to print out a replacement field. Inside of the replacement field, I'm going to have amount and then another replacement field where I will have the transaction type, Then another replacement field or on another replacement field and that replacement field will be open up, these parentheses. Local time was replacement field date as time zone does not always give you the suggestions, but there we go. As you can see, we've created all of this. Let's go ahead and try and test it out. I'm going to duplicate these deposits and make like 2223565. Then, I'm going to do to underscore Michael. Oh, it's wallet. I forgot we're working with wallets now. In here I'll just print out line, show transactions, and add an extra line. As you can see, we've made these deposits. These deposits are being appended every single time we make a deposit. It appends to the transaction list with the following weird code. And the amount to add Apple that has these two items. Let's see what this looks and then we will break it down when I write Click and I run look at what we get. Actually, I'll just Doug it on the bottom. We've made all of the addition of the transactions and we made one withdrawal as well in here, 122, deposit on 2020, 3669, date at 01:22 48 plus this weird number plus 00. This is the Greenwich time. And then finally, we have the local time which was 42248. So, this is my local time time that I am currently in right now. Now, if this number is just too big for you, what you can do is you can do the following amount in here. We can add two dots and six when I right click and I run. There we go. It just adds a few spaces on here to the left hand side so that we, as you can see, first of all right here, the date time zone just gives you the date in my current time zone plus three. Then in here on the UTC. Now it simply provides the time that is right now, but we need to use P YZ module. We will delve deeper into all of these, but for now just know that it simply provides you with the time that the transaction was made of and the amount of money that was deposited. So we extract or we unpack the couple that's coming in of the date and the amount or into the date variable. Into the amount variable, and then we print all of that out. The next thing we want to do is we want to actually not have to write this entire thing in here every single time we want to make an append, because writing this is cumbersome, especially if you're trying to append it multiple times. A better thing to do is to actually have something called a static method that would handle this. What is a static method? A static method is a method that belongs to a class rather than an instance of the class. When we were working before in the person, for example, where we had my, my height was applied to the actual instances to underscore Michael to underscore someone. But now we have a method that is static that belongs to the actual class, not to individual instances. It can be called on the class itself rather than on an instance of the class. Even though we can call any method on the class, we have to provide it with the instance on which we want to make the transactions or the modifications of whatever. For example, when we did person my height inside, we had to provide the self on which we were working. But now with static methods we can actually simply apply it to, for example, the Bitcoin wallet. And we're going to see that in just a bit. A static method is defined by using the at static method decorator. I will show you what the decorator is in just a bit. It does not take the self, obviously, because it's applied to the actual class. Let's go ahead and create a static method that will return the current time back in our code. In here at the top, even before or at the top above the it. Because this is a static, we're going to do the following. I'm going to say at static. Static, okay, it will not show up right now. Wait. Let's first of all define underscore current. Underscore time, I will remove self from here and I should see static method being suggested to me. I will tell you about why we're using underscores later on in this section, but for now I'm going to say that UTC underscore time is equal to date time, date time UTC, exactly what we were using in here. And then I will return yz localize UTC time. There we go. Now we are actually returning this long line and we can remove it. Boom. There we go. And move this as well. In here I can simply type in Bitcoin wallet, do the current time. There we go. So we've made it much, much simpler. Look, we are actually calling the current time on the class. That's what makes this a static method. When I write click and I run, there we go, I get the same output but now with a slightly different time. I hope you understood the freak part. Is this right here, what's the UTC time date And oh my God, so confusing. Don't worry, these are standard things that are used. We will later delve deeper into them. But as always, these are things that we need to understand. On the surface, of course, if you are more interested into understanding these right now, you can always go to W three schools or just search for whatever you want on Google. But now with all of this out of the way, the next thing to do is obviously to also show the withdrawals, because currently we only have the deposits. Your challenge is going to be to append again. Whenever we withdraw from our wallet. We want to append the transaction list as well. Make sure to call the current time static method. Also provide the amount to st subtract, which should be sent negatively. Very important part of the challenge. Pause the video right now and go do the challenge. Okay, welcome back. So how did you get on with that once we do this challenge, this line of code right here which is the multiplied by minus one will make a lot more sense. First of all, on the withdrawal, just like we did before. We're going to append our transaction. We're going to have selfsactlistpend. We are going to have the Bitcoin wallet current time, the amount to subtract. And as I said, it's going to be minus, save that. Now if I scroll down and let's make a few withdrawals and move them in between the deposits and withdrawals. And actually, I will make something like this and I will remove 243. I think that's too much. 120? Yeah, I think we're removing too much in here. Let me deposit like 50. I don't know. And let's just remove five and then we will withdraw 200. Okay. So I think that's good if I right click and I run, let's see. All right, there we go. So let's see if they match what we've done. So 122 deposit, 50 deposit, withdraw is five, withdraw. 120 deposit, 235 deposit and withdraw. So everything matches up exactly as we did before. I think this is pretty self explanatory, there is not much to it, but what we finally need to explain is this amount multiplied by minus one. So we've created the show transaction that would handle transactions, whether they are withdrawals, whether they are deposits. If the amount that we have from the transaction list, let's say it's right here. Okay. On the deposit, if we get this item in the transaction list, we will check for the amount to add. If it's positive, it means it was a deposit. If it's negative, because notice the amount to subtract needs to be greater than zero. So we send in the negative one. It's an LS, which means the amount is negative, it will be a withdrawal. And we will multiply it by minus one in order to get a cleaner output. So instead of seeing in here -234 or -65 or whatever, I -120 and minus five doesn't really look neat. It doesn't look good and it also doesn't make any sense. -120 withdrawn. Mm, You know, 120 with drawn, there we go, makes a lot more sense. So that's why we have this amount multiplied by minus one and we display all of that out. So thanks so much for watching. I hope you enjoyed it. I hope it was not too confusing, especially with these lines of code right here. I know something new, something crazy. Everything that we're learning is new. But that's why I told you the section requires a lot of your concentration. Thanks so much for watching. I hope you enjoyed. In the next video, we're going to be looking at attribute accessibility and understanding why this static method has an underscore behind it. So I will see you in a few. 92. 7. Attribute Accessibility: Welcome back to my favorite Python developers. In this video, we're going to be learning about attribute accessibility. But before we do that, we need to look at a glaring problem that we have in our program that might have not been apparent before. I'm going to scroll down in my code in here and I'm going to remove all of these deposits and withdrawals. Or maybe I'll just comment them out just to keep them on the side. Let's just leave them. It's okay. We can add whatever we want later on. What I'm going to do is I'm going to say that wallet Michael deposit 100 and then I'm going to say wallet Michael withdraw 150. So why is this a big problem? Well, if I write Click and I run, look at what I get, the total amount of BTC is 50, sorry, is 200 and then the total amount of BTC is 50. But if you look at the transactions, you can see that all that we did was we deposited 100 on this date and then we withdrew 150 on this date. So the issue in here is if somebody looks at your bank statements or at your Bitcoin statements, at your deposits and withdrawals, they're going to see that you've deposited 100 and then you withdrew 150. So how is that possible? Something doesn't add up and obviously you're thinking right now, well, that's because we had an initial balance of 100. But it does not show right here. It does not show on our transactions. And it should show, we should be able to see what happened initially, what was the initial balance. So this is going to be a challenge for you to deposit the initial deposit. So make sure that as soon as we create a wallet, we have a transaction added to the transaction list. If you want to go and conquer this challenge on your own, it's not an easy challenge. You will have to think very creatively about what you should do, but try your best, test it out, see what works, see what doesn't. And then if you need the hint inside of the Inet constructor, transaction list should not be initialized as empty currently. If you go into the code, you'll see that the transactions list is initialized as two square brackets facing each other, meaning that there's nothing inside. It's an empty list, but we don't want it to be empty. We would rather have the current time, again using the static method that we created last time with the balance sent as the first element. The first element should be a couple, with the first item in that couple being the current time and the second item being the balance. Just like we did with any normal deposit positive video right now. And go do the challenge. Okay, welcome back. How did you get on with that? It's not an easy challenge for those of you that tried to do it without any hints. I congratulate you. It's very important to try without any hints. The ones that saw the hint and were able to do it. Also very good if you weren't able to do it. I want you to focus very correctly. So the whole idea is that we replicate what we are doing right here on the transaction list append. We want to start off with the transactions list not being empty, but with the Bitcoin walled current time and the amount to add. I will simply copy this and paste it here. But instead of the amount to add, I'm going to have the balance. This should make sense. If I write, Click and I run, look at that. 100 deposited on this date, 100 deposited on this date, and 150 withdrawn on this date. Now if somebody sees your Bitcoin statement or looks at the block chain to be more precise, they see, okay. So there was a 100 deposit. 100 deposit, and then you withdrew 150. All right. Then 50 is the remaining balance that this person has. So great, congratulations. But there is still a massive problem here that we have not addressed or we have not tried to break. If I do the following, I say, wallet underscore Michael balance is equal to 360, then wallet Michael show balance, look at what we get. Where is it? Where is it? Uh huh. Look at that right here. Just before we show the transactions, I actually have 360. And if I duplicate this code and try to run it after the transactions, it's even worse. Because look at that. I made a 100 deposit. Another 100 deposit, I withdrew 150 and somehow I came up with 360 Bitcoins At the end crazy, this is definitely not something that we would like to have. We don't want people to easily be able to access our balance and change it. The even worst part is that I can make this -360 which is like completely breaking everything that we know about money, about everything. So obviously we don't want this to happen. We need to make sure that nobody can access these attributes through any instance. And to do that, we need to make a small change. And that is adding an underscore behind the balance right here. Once that's done, obviously you can see that there are a lot of places that we need to make changes before I go and do the changes. For every single one, I will double click on the balance and hit Control. Or you'll see that now all of the balances everywhere are selected. Now I will simply copy this, paste it in here, and make an underscore. Now I can select, replace all, But there are a few of these that I want to exclude. Like this one and this one. This one for example. This one. This one. This one. That's it. There we go. Now I can replace all, boom, there we go. And all of them have an underscore. You might be thinking, well, how does this help us? Well, first of all, I'm going to remove these. We forgot to exclude these ones and well now let's say somebody is trying to access our balance and modify. He'll do like Michael, and then he will type in balance. He doesn't see that we have the underscore balance. Let's stride this again. He tries to do underscore balance. He thinks he's smart, but again, nothing shows up. Now obviously, if he does this, he does eventually break our code. This is not a perfect solution. There we go. So if I right click and I run, there we go. You can see that they still can access. But at least this underscore has the ability to hide our attributes. Now some of you might be laughing at this point. I've had students that make fun of this strategy of hiding because, yeah, this is not going to stop like some amazing hacker. Obviously, there are other checks and balances at this point that can be used by a developer to make sure that a person or a malicious person does not access the code. But this is a quick, easy fix that hides the functions or the attributes that you have. The sensitive attributes that you don't want other people accessing. Such as the underscore behind the current time. So I promised you I would tell you what this does, and there we go. You can see that current time we have the underscore. It has the same meaning as the one behind the balance. For example, you can start adding multiple underscores. Three underscores the person that's trying to access. How many underscores does this person have? Crazy? So there we go. I hope you enjoy it. I hope you understood the importance of having an underscore. From now on, we will probably have many of our sensitive attributes all having underscores behind them. Thanks so much for watching. I hope you enjoy it. And I will see you in the next video where we will be importing and manipulating data using getters and setters. Maybe I'm not sure still at this point I'm playing around with the course, checking what's good, checking what's not. Thanks so much for watching and I'll see you in the next video. 93. 8. Importing Manipulating Data: Welcome back my fellow Python programmers. In this video, we're going to be delving deeper and seeing the real power of object oriented programming by having multiple files communicate with each other. The first thing we need to do is we need to create a new project, which is going to be our game in the file, I'm going to go to new project, I'm going to go to next. And in here I'm going to call this the oop game. And make sure to select the proper file. And then hit Finish. Yes, this window. There we go. The first thing I'm going to do is create a new Python file. That's going to be the player. Hit Enter, there we go. Make sure to call this file Player with a small P because we're going to create a class inside that has a big P which is the player. But we're also going to make sure to type in object in here. Now if you don't type in object, it will not cause any errors, it will not cause any problems in your code. But we need to get used to seeing this. This is called inheritance. And we're going to look closer at inheritance in later videos but for now we just want to inherit player from object. But to tell you the truth, every single class that we've created so far inherits from the class object. This is not necessary, but I just wanted to show you how inheritance will look like and just start working with it. You can even check out the object class by holding down control and clicking on this class to go to the class object. And this is the base class of the class hierarchy. When called it except no argument, et cetera, et cetera. You can see functions such as the in it are inside of this class and other functions or other methods that we use. Let's close this down and let's go back to the player. In here, I'm going to create the constructor, define the It, and the player will simply have a name. Then we're going to have self name and it's going to be equal to the name lives equals to three. The player will have three lives. Self level is going to be equal to one, and self Xp will be equal to zero. There we go with that out of the way. Now that we have established this class player, I'm going to create another Python file that I'm going to call the main. And this will be the main body of our code. We're not going to write any classes in this file right here, but we are going to be importing the classes from outside. Let me show you what I mean by that. First of all, I'm going to import, I've imported the file player. That's why it was very important to make sure that the file name is with a small P or lower case P and the class name is with a big P. I'm importing the file here, then I'm going to say player, underscore Michael. And again, you can name your player whatever you want. You don't have to name him Michael. And we're going to say, I'm going to send in Michael. There we go. What we do in here from the file, I'm getting the class player and sending in Michael which is going to be the name which is required on the constructor in here. Then I'm going to say that I want to print out player name. To do then player Michael duplicate this player level. And this is not work unless I say, because I believe. Can you allow me to do this? Yes, player level. There we go. And I'm going to remove the art because level is an integer, it's a number. That's why we will need a replacement field. If I write click, there we go. Player name is Michael, Player level is one. We've established a few things. But we can also change the way that we're importing the file by typing in the following. Instead of importing just player, I can do the following. I can say from player import. Player. Now, I don't need to type this every single time, I want to create a new player. I can just say player Michael. Now what we can do is we can start creating massive classes in separate files, and then simply executing them in the main file, which will save us a lot of space. Next, we want to modify some of our attributes. In here, I'm going to print out the following. I'm going to have a star multiplied by 50. I'm going to print out player lives left to dots, replacement field, then player Michael lives. Then I'm going to say my player Michael lives minus equal one. And then I will duplicate this, line control D, shift Alt. Move it down so that we can see what is happening when I right click and boom, there we go. Players lives left is three, then players lives left is two. But the issue with this is that if I do this many times, so if I select these two lines or three lines and duplicate a few times, you probably know what's going to happen at this point. If I write, click and I run, boom, look at that, I get lives minus two. Obviously not something that we want, something that we would like to fix. Something that we could fix, for example, with an underscore behind lives, which will deter the person that's trying to access our lives. But there is a much better way of handling this, and that way is through using property. So in Python, unlike other languages, you have the ability to access attributes without getters or setters. In other languages, this is frowned upon. But in Python, you are considered to be a responsible adult. So they think, okay, even though the user has access to the lives, they will not go through it. But sometimes the user does go through it, he does use the attributes directly. They are not responsible adults, so we do have a way to mitigate this. That way is going to be through properties, and getters, and setters. First of all, let's understand what is a property. Properties are a way to define methods that are accessed like attributes. So similar to the way that we're accessing lives right now, we can create methods that can allow us to access them the way we access lives. They allow you to define a method that is invoked when an attribute is accessed and another method that is invoked when an attribute is set. When I say invoked, I mean called upon or you call a function but a method, but in this situation it's called invoke, called. We can have two methods, one to access the attribute and one to set the attribute. Attribute that is accessed is called a getter. And an attribute that is set is called a setter. Properties are defined using the built in property function. We're going to see how that works. And they are assigned to a class attribute using the ad property decorator, Similar to the static decorator that we've seen before. We also have the at property decorator for example, in our game. It would make sense for us to create a setter and a getter for our lives because we never want to add too many lives to our player, nor do we want to have negative lives. A setter in this case would allow us to set the values properly. So the first thing we need to make sure of is that our value for the setter and the cater, which is the lives, is slightly hidden back in our code on the player, the lives will have an underscore behind it, so it's slightly hidden. And again, as I told you, this is not a way of preventing someone from accessing the attribute. This merely hides it from appearing easily to the user or other programmers. The next thing we need to do is we need to create the setters. And the getters in here, I'm going to define underscore get underscore lives and it will just have the self and we will return self, underscore lives. Then we are also going to define the underscore set. Underscore lives in here. We're going to have the self and also the lives. Now I can say self dot underscore lives is equal. To lives. Now we need to create the property. After we've made these two definitions in here, I'm going to say that lives just lives, Not underscore. Lives. Just lives is equal to property. The property has this parentheses and we will get lives and set lives. Now you'll notice in here that we have a warning. And this is a serious warning because we don't want to have these parentheses, we need to remove them. Now, why do we sometimes have these parentheses and why do we sometimes don't? As a rule of thumb, whenever you have these parentheses, it means that you're actually calling the function. In this situation, we're not calling the function, we are setting the property. We're saying that whenever the user tries to use lives, they are actually using the get lives and the set lives if they're trying to receive the information they're using the get lives. If they are trying to set the information they are using the set lives, the setter and the getter. Let's go ahead and test it out. If we look back in our code, you'll see that we don't have an error, even though we change this from a lives to an underscore lives. And we've seen that when we do this, this should not work any longer. But it does in the main code, we still have everything working. If I write click and I run, look at that, everything works perfectly fine. But there are extra steps being taken in order to get to this point. And I'm going to prove it to you. First of all, I'm going to remove a few of these. I will just have these three lines in here. I'm going to say that I want to print out, hey, I'm in the getter. Hey I'm D setter. When I write click and I run, look at what I get in here. First of all, let's go line by line. When I said print player lives left, player Michael or player underscore Michael lives. First of all, when I arrived at this point and I said lives, we went into the player class, we scrolled down and we found that lives as a property and we're trying to get the information. So we called upon the get lives and that's how we got, hey, I'm getting I'm in the getter. We retrieved the information, we sent it back, and we were able to print out player lives left three. Then we had this player underscore Michael dot lives minus equal one. What happened here? Well, what happened is we have getter setter. And then we had the getter and placed the player lives left to this line of code belongs or has these two. But the dot lives needed these two lines. So it first needed the getter and then it needed the setter. Why is that? Well, because we first of all needed to get that information. When we set player underscore Michael Lives, we got the information, We went to the getter, we received the information. And then we did a minus equal one and we sent it to the setter right here. Okay. I know it's a bit confusing. This is not an easy concept to wrap your head around. I even remember having trouble with this myself years ago when I started learning about decors and the setters. I'm like, okay, this doesn't make sense. How does that work? When you do it once, twice, three times, you finally get used to it. It's very important to know how these things work. That's why I had these prints for debugging purposes, but for now I'm going to comment them out with a control forward slash. But keep in mind that this works perfectly fine if I try to duplicate these several times. As you can see, it all works perfectly fine. Now we do have a warning here, cannot be set. It's a bit confused, because even though our code is still the same, it's a bit confused. But no worries, everything works perfectly fine. But there's still the issue of having minus one and minus two lives and even zero. The player should be that. At this point, I have a challenge for you to set the setter. Make sure that the lives never goes below zero. Test it out in your main, that's basically it. Where should you make sure of this? You should make sure of this in the set lives, in the actual setter that we've created. Pause the video right now and go do the challenge. Okay, welcome back. As you can see in here, we have the definition of our setter. What I'm going to do is I'm going to, first of all, this one I'm going to move to the bottom. Actually, I'm just going to delete it. I don't want it anymore in here. I'm going to say if the lives that we're trying to set underscore lives, if lives is greater than zero, then I'm going to set the lives strictly greater than zero. I mean, you could say greater than or equal to because at zero you're actually dead. But we haven't accounted for that. But that's okay for now. We're just going to say greater than else, meaning that if we are definitely in the negative, I'm going to print out lives cannot be negative and self lives equal zero. There we go. Notice that I said self live. I'm referring to lives that is right here. I'm setting it. If you go back into our main and right click and we run, look at what we get. Lives cannot be negative, lives cannot be negative twice. When we tried to do minus one and minus two, this did not work and we received a printout that lives cannot go below zero. The last thing I want to do in here, even though this video is very long, thank you for bearing with me. And that is the underscore underscore SDR. So if we wanted to print out everything about our player in a cohesive way, like the name, and the lives, and the level, and everything with it, We can do something like this. You can create the underscore underscore SDR. Boom, in here we can return whatever we want. I'm going to return name to dots, replacement field. I'm going to show you something that's a little bit weird. I'm going to say zero name weird, isn't it? It's going to make sense. Then I'm going to say lives to dots, zero lives replacement field. Then I'm going to say level to dots replacement field zero level. And then P two dots replacement field zero Xp. And then at the end I'm going to say format and self. This is simply the replacement for the self. The self is replaced in here and then we're using the dot name. The zero represents the self in here every single time. This is just a small short cut, something that I wanted to show you. If we cover the SDR, we can go through the documentation. It's basically whenever you want to print something out. Now for example, instead of saying all of these things or instead of trying to print out the name and then the level on separate lines, I can simply do the following. Print out player Michael. Boom. And look at the output. Okay, what is the problem? Two lives, no attribute XP. What is it called? Xp, small p that I write in Big XP. I apologize. Let's run it again. Okay, no issues. So there you go. Name lives, level, and XP. Ladies and gentlemen, I hope you enjoyed, I hope this was not too confusing. Sorry for the long video, but these are very important stuff that we are delving into. I'm going to see you in the next video. Hopefully, if your brain hasn't exploded so far, where we will be looking at data management and structuring, which means we are going to delve deeper into properties and data attributes. I will see you in the next video. 94. 9. Data Management and Structure: Welcome back my favorite Python developers. In this video, we're going to be looking deeper into data management and structuring as you've seen before. Now we have a set lives and a get lives that will allow us to avoid certain problems. I'm going to remove these for now because we already know that everything works. But again, as we've said, this does not prevent somebody from doing the following. Doing underscore lives, for example, and setting it to -13 Then if we print out Michael, there we go, we'll see that lives is -13 Again, this is a problem, but only for someone looking to really break into your code. When you see an underscore while trying to get an attribute, you should realize that the developer put it there to protect it. And if used directly, could cause problems somewhere down the line in the code. But now let's look at creating more properties for our player to make the class more dynamic. And when I say let's create some properties, I mean you should start creating some properties by getting and setting the XP. Create a getter and a setter for the XP. For the setter of the XP, we want to increase the level every time XP goes to 100. Make sure to add them to the property and test it out in your main. Okay, pause the video right now and go do the challenge. Okay, welcome back. So how did you get on with that? So the first thing we need to do is back in the player, let me close this down. The XP should become underscore XP. We need to protect our experience. And then I'm going to scroll down, right here to the bottom, and define the underscore, underscore P and return self Xp. Then I'm going to define the underscore set. Underscore xp, it will only have the self, the xp, underscore two. Underscore, I'm going to have self xp plus equals to the xp two. Now if self dot underscore xp is greater than 100 than self self level set level plus equal one and the self x will be minus equal 100. Now why do we do the minus equal 100? Because obviously we want to remove 100 P. Then in here we're going to do the following. I'm going to say that X P, big X and Big are equal to property on the property. Underscore get X P. Underscore set P. There we go. We've created the getter and the setter for our XP. The first one simply returns the XP that we have. The second one takes in an argument, which is the XP to add, and adds it to the self underscore XP. Now you'll notice that these two setters are slightly different, whereas in here, we would simply set the underscore lives to be equal to the lives directly that's being sent. While in here, the self underscore XP is done with a plus equals to the XP. To add that is the two different ways that we can create a setter. For example, in here, player underscore Michael lives, we would have minus equal one. We would actually get the property and then remove minus one from it and then send it to the set lives, and it would set the underscore lives to that. But now we're going to do things a little bit differently. First of all, let me, I will comment these out, everything in here, I will comment it out and move it to the bottom. Then in here I'm going to start removing Xp. I'm going to say that Michael Xp. And actually know what having a big X is, a bit cumbersome in here, small x, let's just make it small Xp. I think it's better in here. We'll have Xp equal 20, then we will print out Michael. And then we'll have a print. If I click and notice in here I didn't say plus equals or minus equals, like I did with the lives. I said it's equal. Now this 20 will be sent to the XP. To add, it will be added to the underscore P, and then we are going to check if the underscore XP is greater than 100. So that we can level up. When I write click and I let me add this right here to the right hand side. There we go. We can see first of all, player underscore Michael x equals 20. I don't need to print this one out, I just want to make everything makes sense. There we go, p 20. Now if I duplicate this three times, maybe add a little bit more. So in here 32. We'll duplicate this again. In here I will add 88. If we write click and we run, look at what we get. As you can see, first of all, we added the 20. Here's the 20. We added another 20, so now we have 40. We added 32, we have 72. Then when we added 88, we had the following 72 plus 88, boom, 160, And then -100 we leveled up and we are left with 60. So everything seems to be working correctly for us. So there we go. Ladies and gentlemen, we've created the XP as well, and we've seen a different way of creating the setter. Let's now look at a different way of actually creating the getter and the setter. If I go back in here, I want to obviously make sure that the level is also protected with an underscore. And then I'm going to scroll down in here and I'm going to say at property, this is the property decorator that I told you before. I'm going to define the level self, which will return self underscore level in here. I'm going to say at level setter, I'm creating the setter. Define level level in here. I'm going to say self underscore level is equal to the level. The reason I'm seeing equal in here and not plus equals is because of the way we are increasing the level and here with a plus equals one, similar to how we did it with the lives as well. Okay, hope that makes sense. It is a little bit different in here. Now notice these are the same get which returns the and for the set are the same. Remember when we were trying to access a property like P, we would simply say player Michael, and automatically the program would know whether our Python would know whether we should be using the getter and the setter. The same principle holds true here. We have the same name for our setter and getter, but they do different things based on what is provided to them or how they are used. Now if we go back into the main code, right click and run, we should have the same output if we try to do the following. Michael level equal to six, for example, print out Michael, right click, run, and there we go. So we are actually setting it directly and we don't need the print here. There we go. Level is six. So we're actually setting it. We haven't increased it. We've actually set it. Ladies and gentlemen, I hope you enjoyed this video. Sorry if that clap was very loud. And in the next video, we are going to be looking at inheritance and how it works, and why it works, and why it's needed and why it's so important. And we are going to continue building the project that we have currently. And you'll see at the end that this project can really be expanded upon. We're just doing surface level things to understand everything properly, but you can always increase your knowledge, expand the projects, expand on everything. Thank you so much for watching and I will see you in the next video. 95. 10. Inheritance 101: Welcome back my fellow Python programmers. In this video, we're going to be looking at inheritance, which is a very important part of understanding object oriented programming. You're going to see inheritance all the time. Now in this video, we're not going to be creating inheritance, We're going to be understanding inheritance and setting everything up. And in the next video, we'll be creating the subclasses and so on. But for now, what is Inheritance? And Python? It's a mechanism that allows a class to inherit properties and methods from a parent class. If you create certain properties, certain methods, certain attributes in your initial class, you can then give them to a child or a subclass down the line. So you can inherit, see, that's where the word comes from. A child class is defined by inheriting from a parent class using the child class parent class syntax. Similar to the way we created the player. If you remember, we said in between two parentheses that we inherit from object class. The same holds true when working with any child class parent class relationship. The child class can also define a new properties and methods, or even override the ones that they inherited from the parent class. So let's say the child inherits from the, from the parent class. They inherit the family name, for example, but they can override the name, right? They can have another name. This is just a very simple example. They can inherit the money, but they can override or add methods on the way that they spend that money. That's just a broad example. We will see a lot more of this later on. Inheritance allows for code reuse and reduces the amount of code duplication. So let's say you have a class where, I don't know, maybe later on we'll see an example in just a bit. So let's say you have a class that is a mammal, for example, that a mammal gives birth. What the normal way that a mammal gives birth? Instead of having to create the method for cats to give birth, For example, you can make the cat a child of the mammal class and then inherit the birth. That example is so weird, but I will continue at this point to invested In this example, the cat inherits the birth method from the mammal class. And now instead of recreating the code, instead of duplicating the code for the cat, we can simply inherit from the main mammal class. And the parent class is also known as the superclass or base class. You'll see those two definitions for a parent class in a lot of places. And the child class is also known as the subclass or the derived class. With that out of the way, let's look at a common structure for inheritance. So for example, we start with an animal. That animal would have a name and a species, correct? The dog would still have a name and his species would be dog. The cat would have a name, a species and the breed. Now obviously dogs also have a breed. But just for the sake of this example, let's imagine that only cats in this case would have a breed and notice how they inherit from animal. Then we have horses and birds. They all have names and they all have species. But then the cat also has a breed. So now we can create a subclass of the cat. For example, the Siamese cat, which has a name, a species, its own breed. And the Ames has a special method in it that allows it to jump, which is different than all of the other ones. Again, for the sake of this example, I know horses can jump. Also, we have the Bengal cat, which can meow very strongly. Then you have the Sphinx that can attack. As you can see, this is a structure of inheritance where cats inherit from animals and CM is Bengal, and Sphinx inherit from the cat. And the horses would also have their own subclasses and so on and so forth. I hope you understood how this works. If you haven't, I recommend that you go through the slides again. Once you do you have a challenge in front of you. You'll need to create an enemy. First of all, create a new Python file, call it the enemy. Again, lower case inside. Create the enemy class with the following attributes They should have name, health, and lives. These are the attributes a method take Damage with an argument, damage taken, Remove the damage taken from the health. And if the health goes below zero, take a life away and print everything using a underscore underscore SDR. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? I'm going to go into new and create a new Python file that I'm going to call the enemy. Inside of the enemy, I'm going to define a class enemy. It's not going to inherit from anything. An enemy is not written like that. There we go. Is that how you read enemy? Yeah, I think so. Then we're going to define the in the in it is going to have name. We're just going to set a default value for the name just in case somebody doesn't provide us with it. The health equals zero. Let me remove this in here. The health equals zero and lives equal to one. Then I'm going to say self dot name equals to name. Self health equals to health. Self lives equal to lives. There we go. Next we're going to define underscore damage, and we're going to have the damage underscore taken. First of all, we're going to calculate the remaining health underscore health is equal to self health minus damage taken. And we're going to check if the remaining health is greater than or equal to zero, which means we're still alive. We're going to say that self health is equal to remaining health, and we'll simply print out a small thing in here. Damage two dots, replacement field, damage taken. Then we are going to say health remaining two dots, replacement field. And we're going to say self health. There we go. If you want, you can even add back in here. Maybe that would be nice to back, I don't know. We'll see how the output looks and we'll adjust accordingly. But then we need to also check if the health is less than zero, then self lives minus equal one. And I'm going to define an SDR where I will return the my name replacement field zero. Name, Come on, lives replacement field zero. Maybe I should have said the health first. I don't know health two dots, replacement field zero. Health format self. I'll just hit Tab or hit Enter. Hit Enter in here so that we can see everything. And hit two tabs or two enters. And there we go, we have the class enemy which has the constructor takes damage, takes away a life, and also has the STR back in our main right here at the top from enemy import enemy. What do we have in here? I will actually comment all of this out as well. I will comment up until this point. Boom. Just keep Michael in there just in case we need him. At some point, I'm going to create a enemy underscore monster and I'm going to say that it's equal to the enemy. The enemy will be just a generic monster for now. Of course you can have fun with this health, I believe. What is it on the constructor? Can I see? The health is going to be 12 and lives will just keep it at one. For now, I will print out the monster. Let's take a, there we go. We know what? Let's just take eight damage here. And a print would be nice when I right click and I run. Let's look at the output that I get. All right, does it look good? Health remaining. What's this enemy monster? Okay, I think we don't need this. Since we're printing, we can print it out at the end. So right click and run. Let's see what we get. Hm, take damage health remaining. Let me check again. What did I do in here? It seems like it's a little bit wanky. We haven't, we didn't go into a new line as well. Let's try this output right now. Health remaining zero, you can see right here, health zero. Maybe because we're exactly while it's greater than or equal to zero, okay, so maybe we should take nine lives in here. What happens? All right, there we go. So health zero or lives is zero. And we didn't even print out that the damage taking and the health remaining because we don't have it right here. I'm not sure about this output, honestly. You know what, I'm just going to remove these. I think it's not that good. Maybe add like a pipeline. There we go. Looks a lot better with the pipeline, in my opinion. As you can see, the enemy monster lives one. And we forgot to add the two dots. Small things that we need to adjust in here. And I'm just showing you the process of creating things. Sometimes you need to go back, just look at what's happened, what we can improve. Notice that we still have a problem in here where the health was not taken. Because when we removed it, we did not adjust it. We still have health, but we don't have any lives. Again, this is not a perfect program. What you can do, you can, for example, set the self health to be equal to zero. If you want that, maybe it makes more sense. But again, you have to also take into consideration that when you remove a life, do you want to take back the entire original health? Do you want to store that health? Maybe somewhere in some kind of variable on the enemy. So a lot of questions, a lot of small minute details that need to be handled before this is a actual working enemy class for an actual game. But for now, this is what we have and we'll stick with it. Thank you so much for watching. In the next video, we are going to be creating Orcs. We're going to be creating succo buses as subclasses to our enemy. And they are going to have their own methods and a change in the properties. Thanks so much for watching. I hope you enjoy it and I will see you in the next video. 96. 11. Creating Subclasses: Welcome back, my favorite Python programmers. In this video, we're going to be creating subclasses and overloading some functions. Let's go ahead and get started and understand what all of this is about. First of all, we're going to create a subclass of the enemy instead of just having generic enemies. We're actually going to be having an Orc in here. I'm going to go ahead and create a new class Orc. And it's going to inherit from enemy as you can see, just like we did previously I believe with player right here. So player inherits from object, the Orc inherits from the enemy. I'm simply going to add a pass in here. So the pass will allow us to not write any code because I don't want to define anything in the Orc just yet. I simply wanted to inherit from the enemy which will allow me now to go into the main and from enemy, import the enemy class and also import the Orc. Now I'm going to scroll down and right here where we're creating the enemy monster. I'm also going to create Orc. Or actually you know what, we'll create it here. Orc one is equal to Orc. The Orcs name is going to be Saga. There will be 16.2 You'll notice that we have health and lives. For the health and lives and then we'll print out or one. If I read click, I look at what I get. Right here, I have the enemy name which is Saga with lives two with health 16. But what is happening or the enemy you can see right here doesn't have anything in it. Even though there is nothing in the Or class, we are still able to create an object of the type Or and printed out with the format. Why? Because Orc inherits from enemy in here. When we say Or saga 162, basically what happens is we create the Or object and it takes all of that information and sends it to the in it. But what if Orc had a constructor of its own? That's going to be a challenge for you. You need to create another Orc in Maine, Create another Orc and call him Zc, and add a health of 22. And I don't know how many lives. Maybe you can just leave the lives open. Keep the live. There we go. Sometimes I need to review my challenges. Keep lives field empty to take the default value. Now create an in It or a constructor in the Orc class and keep it empty. Meaning simply pass, add a pass. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? The first element of the challenge was creating another Orc with a health of 22 in the main. In here I will create Orc two. And I'll say that Orc two is Orc 0.22 And then I will print out or two when I write click and I run there, name Azog lives one health 22. Now the not so useful thing here is that we could have made these Orcs just enemies and it would have been the same outcome. We obviously want to have more functionalities to the subclass that we just created. Let's go back into the enemy's file. And under the Or, I'm going to define underscore, underscore in it. And I will simply have a pass in here. And let's just have one attribute or one parameter and save that. Now notice immediately we have something weird with the It call to it for superclass is missed. Some things in here are a bit weird. But if you go back into the main and we run, so even before we run, you can obviously see that there are problems in here because of all of the warnings. But let's try to right click and run anyway and see what we get. There we go. We got an error. We were expecting that, kind of So you can see everything was working well until we got to creating the Orc right here. We can see that on line 18, we can even click in here. And. Line orc equal or in. It takes two positional arguments, but four were given. The it in here takes the self and the name, but we provided it with 44. First one will be the object, which would be the self, and then the name, the health and the lives immediate error there. What's the problem? This is because Python no longer finds the init method of the enemy class and can only use the one given to the Orc. Which if we go back in here, does not have enough attributes waiting, or enough arguments to be taken in order to pass it on to attributes. There are two ways of mitigating this problem. Or to be more precise in calling the constructor of the enemy that's at the top. The first one is doing the following. In here I will simply type an enemy.in. It hit Tab, and you'll see that in here I can pass in the Self. I can pass in the name and say that name is equal to name. And then I can say lives is equal to one. And these are just default values and health is equal to 20. And let me just make this slightly bigger. We can see now that everything will be passed to the top. But do we still have any warnings? Nope, this should be good. So back in the main when I write click and I run, I still have some errors in here, but when I write click and I run, oops, there we go. We still got an error in here. And the reason for that is we still have not provided the arguments right here on the, in it of the. To make this event even simpler, what I can do is I can say super in here. This is the more common way of using this instead of the self. We can just remove it. And now we can use it like this. If we go back into the main right click run, we still have an error. What we basically do in here is we need to remove these two and remove this one. And now when I write Click and I run, look at that. I've created Shaga and I've created Azoc. And they have a health of 20 and lives of one. And obviously, if you want to have real control over the amount of health and the amount of lives, you will need to add them right here on the arguments that are presented to the int. But that's basically how inheritance would work. How we call the superclass, always use super with parentheses. Using the enemy in here is not the most common way. Now let's go ahead and create a method that's only inside of the Or. In here, I will define a method. That's going to be the charge, define charge. It's going to simply take the self and we are going to print out in here replacement field. We're going to have self name charged, you charged. There we go back in Maine. Let's go ahead and print out a few stars in here multiplied by 50. And we're going to have Orc one and duplicate this and we'll Or two charge. When I write click and there we go, Sag. Very nice. Now for the last example, let's try something a little bit different. I'm going to create enemy one. Just a random enemy which is going to be off of the class enemy. We're not going to send in anything. Then I'm going to say enemy one charge. Look at that when I try to right click and run. Look at that trace back enemy charge. The attribute enemy has no attribute charge or method charge or anything regarding charge. Charge cannot be used by an enemy object. That is a very important distinction to make. We cannot go upwards. When it comes to the hierarchy, we can only go downwards. The enemy cannot use the charge, the Or can use the charge, and the Orc can take damage as well. In here, if I try to say Or one take damage, there we go, you can see that I can actually damage the Orc. And when I write Click, I still have this issue right here. I will comment these out. Boom, there we go. Damage, take health. And the health remaining is 18. Can use methods from the class that I've inherited, meaning like Orc inherited from enemy. Or can use methods that are in the enemy. But the enemy in the enemy cannot use methods from the class. Or thanks so much for watching. I hope you enjoy it. In the next video, we are going to look at dynamic method implementation where we will delve deeper into how all of this method using works. I will see you in the next one. 97. 12. Dynamic Method Implementation: Welcome back to my favorite Python developers. In this video, we are going to be looking at dynamic method implementation. And also meaning that we're going to be changing behaviors of certain methods. But before we get started, we're going to start off this video with a challenge where you will need to create a subclass of your own. Create a pycobus class which is going to obviously be inheriting from the enemy class, meaning that the sucobus is going to be a child of enemy. Add a constructor to it and call the superclass imported from the, meaning imported to the main. And create a saccopus object called astarroth. That's basically it. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? It shouldn't be too hard, basically. In here we're just creating a class which is going to be the succabus it's going to be inheriting from the enemy inside. We're going to define the in it. It's simply going to have a name. And then we're going to do inside of super, we can also do the following. We can say succobusaseelf in it. Then we will say name is equal to name lives is equal to three and health is equal to ten. There we go. Now that we have the succabus, let's go back into the main in here. I will print out just an empty line, and I will copy this, paste it in here. And then just have another empty line. And I will do the same. And this because I want to start differentiating between different sections of our code because the output is starting to get very long in here, I'm going to have the succobusecup. First of all, of course, we need to import it succobus. Then in here, I'm going to say that I have the succobus one equal to succobus. There we go. I said it's going to be astro. Is it asosaroth? Yes, exactly. I'm going to print out sacobuswe. Let's see what we get when I write. Click and I run. Boom. There we go. Enemy name Astaroth lives three health. Then in here I will get Saco one damage and we'll take damage of three and we will print out succopus one. Let me copy this and do it a few more times. There we go. And then we'll change three and we'll also have like I think nine and then nine and then maybe, I don't know, another nine. I guess If I right click and I run look at what I get, take damage three health remaining seven and then I go lives three, health seven, lives two, health zero, health zero, health zero. But this is because we had this protection right here where we said the health zero whenever the health remaining is not greater than or equal to seven. If we try to do this again, do I still have it in the copy in the base? There we go. I'll change this to another nine and another nine. When I write Click and I run, look at that, I am getting lives negative. Even lives at zero is not something good. This is a problem in our game. We need to modify a little bit in our class back in the enemy. I'm going to create an extra attribute in here that's going to be the self that is underscore. That is going to first of all be equal to false. This variable is going to change whenever we die to a true. Now in the take damage I'm going to add an extra thing in here inside the, elsewhere. I'm going to check if self lives is greater than zero, then I'm going to print out, okay. No, thank you. I'm going to print out the following. Self dot name is dead, else. I'm going to print out name. If lives is still greater than zero, we're going to print out self name, life. Then in here we're going to say that in here we'll say dead is equal to, there we go. Now in here when I write Click and I run, there we go. Astroth, last life, last life is dead. Is dead. But I'm still getting lives minus one. So that issue has not been fixed yet. So if we go back into the enemy under the take damage, what I'll say in here is I'm going to add an extra condition. If not underscore dead. Okay, we need the self is dead. If we're not dead, we will be taking all of the damage. And else in here, this level mind the indentation else, print out self dot name is already dead. There we go. So he's already dead. Don't continue like destroying him. You should know by this point that the enemy is already dead. And I ran the wrong file. So when I right click and I run in here, there we go. Lost a life, lost a life, lost a life, and then he is already dead. So the lives, we are no longer dying. And you'll notice that this was much easier than going into every single A class. Let's say changing individual ones. Now we can simply change one, take damage, and it's applied to everyone. For example, the succopus now prints out the name of the scecabus and says that it's that, look how efficient our code is. Instead of having a take damage on each and every single class, and then having to change that, making sure that all of it works. We can do it in the main class, in the upper class, in the parent class. Note also that we have these weird symbols, these discs and arrows pointing down, and this disc and an arrow pointing up. And we're going to talk about that in the next video when we talk about overriding subclass methods. I will see you in a few seconds. 98. 13. Overriding Subclass Methods: Welcome back to my favorite Python developers. In this video, we are going to be looking at overriding subclass methods and understanding what these weird rings with arrows are all about. First thing we want to do is we want to give our Orcs the ability to actually block an incoming attack. So if I scroll down right here to the Orcs, I'm going to define the method blocked. That's just going to have the self, I will import random module, so you should know what the random module is at this point. And I'm going to say if random rand 1-9 is greater than or equal to six, then I'm going to print out the following. I'm going to say self dot name has locked an attack. I'm also going to return true, just like we learned in the previous section where methods or functions we used to call them functions because they were outside of the class. But people use it interchangeably, so don't worry about that. You can call them classes, you can call them functions. But as a rule of thumb, when it's inside of a class, it's a method. When it's on the outside the window code, then it's a function. Just like functions, methods inside of classes can also return the value. This returns true. If we did actually block else, we will return false and add an extra space in here. Now that we have this blocked message, sorry, method, I'm going to go back into Maine and I'm going to comment everything out in here because we want to keep this clean and fresh with nothing inside. I want one thing in here. I just want one which is going to be, there we go, I will print out this Orc when I write, click and I run. There we go, Enemy Name Saga Lives One Health 20. Now what I'm going to do is I'm going to create the following. I'm going to say Or Do is dead, while the Or is not dead, I'm going to say Or Damage and the damage will be one. Now if I write, click and boom, there we go. We keep on taking damage until Saga is dead. But we don't want sage die. Well, at least we don't want him to die this quickly. We want him to use the new ability that we've provided, which is the block. And it's going to be a challenge for you. You will need to help out an Orc. Make sure that Snagaor Saga, or whatever you've called your Orc, to be honest with you, only takes damage when he has not blocked an attack. A small hint, even though I haven't written it. This should happen inside of the whileloop past the video right now and go do the challenge. Okay, welcome back. How did you get on with that? This is pretty simple. Inside of the Y loop, I'm going to say if not or blocked, boom. Or do take damage. Now if I write click and I run, I should see the following, boom, there we go. Damage taken on damage taken one, Then Saga has blocked, taken damage, damage take damage. And then we blocked, and then we took a bit of damage, and then we blocked until finally Saga is debt. As you can see, some of the attacks were blocked. Now this is all good, but we don't want this to be happening on the outside, meaning in the main. We want this behavior to be changing while we are still inside of our classes. In order to do that, we need to override the take damage method in the Orc and make it do something a little bit different back in our enemies right here, inside of the Or. I will scroll down and I'm going to create or define the underscore damage. And you'll see immediately I get suggestions at. I hit Tab and I will print out, or let's just make it capitals, this take damage is in the Orc, not. Enemy. Now we know that if we take damage that we're taking damage inside of the Orc. Notice when I define this take damage, I got this circle with an arrow pointing up. If I hover over it, it says that overrides method and enemy. If I go to the top on the take damage, you'll see that I also have this disc with a white arrow pointing down saying that is over ridden in the Orc. So basically what this means, overwritten means it was written or modified in a different way in a subclass. This is when we have an arrow pointing down right here, we can see that the in it is overridden in the Orc and the sacabuscae on the enemy. We have the in it, on the saccobus, we have an in it. So it was overridden in two places. And we can also see right here is a subclass by Orc and the succopus, it shows us a subclass, It shows us when something was over ridden, et cetera, et cetera. Now the question is why do we have a arrow with a red pointing upwards? Doesn't that mean that the underscore underscore STR was overridden? Yes, it overrides method in object. Remember, every single class that we create inherits from object. Hold down control. Click on underscore underscore STR and it's not taking me, no usage found. Okay, very nice. Let's try and find the object ourselves. Object, hold down control, go to object and scroll down until we find underscore underscore STR. Will it find it faster if I do this? No. In the built ins underscore underscore SDR. There we go. So as you can see now the SDR was overridden from the object, but we don't even have to say that enemy inherits from object, every single class will always inherit from object. All right, so I hope you understood what is going on and here I hope you understood why we have these discs. It's pretty simple. Nothing too complicated. Now if we go back into Maine and we right click and we run. Uh huh, Interesting look at that. So we seem to have created an infinite loop. So if I pause this and I go back to the top, you'll see that Haga has blocked. So Haga is blocking some of the attacks, but we keep taking damage without end. Why is that? Well, because now when we take damage, when we call the take damage, it's actually calling the take damage that's on the Orc because we're using it on an Orc object. So it's using the take damage on that Orc. And you'll see that take damage on the Orc simply prints this out and doesn't do anything else. We need to modify this in our take damage so that it actually cause take damage in the enemy. I'm going to say, if not what's called blocked, there we go. I'm going to say super. Open parentheses, Orca take damage, Excuse me, I apologize. Take damage because we're calling the super and we need to send in the damage taken. Damage taken equals damage taken. Now in the main, I don't need this line anymore. I can remove it, shift, and when I write click and I run, boom, there we go. You can see that we have all of these attacks, or some of these attacks being blocked. And it's happening all inside of the class, instead of having to do these on the outside. As you can see, some of the attacks are being blocked, which is great. Our game is really coming into play. But let's say at this point we want to change all of our attributes and make them protected or private. Well, what we can do is go into the enemy and have to change every single one. Or we can do this in a much better way. I can, for example, double click on name, hold down control R, and then change this to underscore name everywhere that it appears. And I can hit Replace, all but some of them you might not want to replace. So you can click on this one and exclude this one. And these should be changed. You can, What else do we have? I think this one you can exclude. And this one. And notice that I have the exclude being pressed right here. This one as well. This makes our life much easier. Now, hit the replace, all boom, there we go. Everything was replaced. You close it with the small x right here at the top. And look at that. Now, name is protected except for an unexpected argument. Oh, we should have excluded these ones as well. I apologize. Now you can see that it's much better. Let's try to run it and see if it works. Yes, it does. Now I'm going to give you a small challenge. It's not an official challenge, but make sure that everything in here is also protected from outside interference with a small underscore. Thanks so much for watching. I hope you enjoyed. In the next video, we are going to be looking at nested subclasses, meaning it's going to be subclasses inside of other subclasses. Wow, I will see you in a few seconds. 99. 14. Nested Subclass: Welcome back my fellow Python programmers. In this video, we're going to be learning about nested subclasses. Or to be more precise, we're going to learn about creating subclasses out of other subclasses. So let's go ahead and get started. First of all, we're going to create a subclass of the Or. In here we have the enemies, we have the scopus, but both of these Orcs and succobuses inherit from the enemy. Now we're going to create the Orc, we're going to create a class, which is the uruk. Hi, that's how it's written. I've Googled it. I'm going to send in the Orc inside of the, inside of the Or. I'm going to define the in it. And we're going to have a name, that name is going to be sent. I'm going to say super open up the parentheses in boom. And just say that name is equal to name. There we go. I'm also going to say that self health is equal to 140. What's the problem typo in the word k? All right. Nobody knows how to write properly. Chi, it's a made up name. One thing to keep in mind is that when you call the super, it's not the original it that is called, meaning the original in, in the enemy. It's the it in the Or class right here. This in it is being called when I do the super. And you can even double check by hovering over this in it and you'll see that it is overridden in Ork. There we go. This is where it's been overwritten. Next, we would like to override the take damage as well to make it not as bad for the Or In here I will define the take damage. I'm also going to make sure to call the super class and take damage. But the only difference is that I'm going to send in the damage taken divide divided by two. Meaning that, remember the divide did make sure to remove any thing after the floating point. The take damage is basically divided by two and then sent to the take damage. So with that out of the way, we can even trace, even look at that. Now this is interesting. Look now on the take damage on the Orc, we have two arrows, 1.1 pointing down. The down means that this stake damage was overwritten in the Ork, while the pointing up says that it overrides a method from the enemy. And if you're ever confused on where this stake damage is being overwritten, hold down control and click on Take Damage. Yes. Okay, that's not what I wanted. Let's see. Holding the control and clicking on the actual method. A wait. You can click on the disc. There we go. This is the take damage that's been overwritten inside of the Orc. Very nice. Now, where does this override the take damage on the enemy? And we can also use this going down and look because we have two overrides. However, over this, it's overridden in the Or and the Or there. Go to the Or, Or go to the Or. As you can see, we're overriding. Now, there is a challenge that you need to do, which is to help Sauron out. If you don't know what Lord Ring is, you're probably thinking what the hell is happening in these lessons. But Sauron is the evil man behind all of these shenanigans, the orchis and whatever, even though that's not Lord based. But anyway, anyways, in the main import the Orch class, create a new chi, call him blurts and print out the object. Apply some damage to him, but please don't kill him yet, because we need to print out the objects again. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In the main, I will add a and add the chi in here as well. I'm going to comment these lines out because I want to keep it clean. We're testing the chi. I will say one is equal to the. The name is going to be lets. I will print out the one, then K take damage, 12, print out. If I write click and I run, first of all, the enemy name alerts lives one health, 140. Remember it doesn't just take the health as it is normally in here. We actually want to have a health of 140. This is very important. Then in here we print out the orch, sorry, we've already done that. Then we take damage. So you can see that we've taken the damage damage taking six health remaining 134. And then we print out and this is the output that we get notice, even though the damage should have been 12, we only removed six. That is because as we said before, we take the damage, we divide divided by two and send it to the top. The damage taken, that's called on the archive, is divided by two sent to the damage taken. Boom, it's sent right here. We call whatever at the top. And notice that we also have the chance to block. This is another unofficial challenge for you to try and block, or try to do multiple attacks. Try to damage the alerts further more times, and see if he can actually block some of these attacks. That would be very interesting to know. There we go, He actually blocked it, and you can see that his health stayed the same. Thank you so much for watching. I hope you enjoyed. In the next video, we're going to be learning about polymorphism, moving away from the current game that we're creating. But polymorphism is very important, a little bit more complex. But it's definitely worth it. Thank you so much for watching. I hope you enjoy it. And I will see you in the next video. 100. 15. Polymorphism: Welcome back my fellow Python developers. In this video, we're going to be looking at polymorphism. What the heck is even polymorphism in Python? It's not just in Python. Other programming languages that have object oriented programming in them have polymorphism. Not all of them, but most of them. Polymorphism. Polymorphism is a concept in object oriented programming that allows objects of different classes to be treated as objects of a common parent class. It allows for a single interface to be used to represent objects of many different types. An example of polymorphism and Python is the use of the plus operator for addition, but it can only be used for catenation between strings. It's the same operator, it's the plus sign. It could be used to add two numbers, or it could be used to Kcateinate two strings. Or it can be used to create a single big list out of two lists. There you go. That's a great example of polymorphism. It allows for more flexible and extensive code. Let's go ahead and test out polymorphism back in my code. In here I'm going to open up one of our recent projects which was object oriented programming. In this window, if you remember, we were working with the Bitcoin wallet. I'm going to create a new Python file that I'm going to call the H or HP characters. Hp stands for Harry Potter. There we go. Enter. And as always, Intellij just freezes for some reason. I will use the magic of editing to see you later on when this works. Here we are. First of all, I'm going to create a class of wizard. I'm going to define the it and we're going to have just a name and we'll say self underscore name is equal to the name. Then we're going to define speak and we'll return Hello, my name is then. Plus self taught, underscore name, plus I am a wizard. Nice. Then we're going to define a class that is which, and we'll define a in it will also have name. And we'll say self underscore name is equal to name. And we'll define speak. We are going to return and I write hello with a W here. I will say, well met I am plus. Self underscore name plus and I am a which I made a little bit of an adjustment which will say well met. It depends on where you are in this world, you might not know. But this is a way to greet people. I think it's the British way of greeting people. I can do the accent, especially with my runny nose. That's why for the last couple of videos I might sound weird and I'm starting because I can't breathe through my nose. I can only breathe and talk through my mouth. So it's hard. But anyway, well met I am with the name and then the which just a little bit of a difference. So we know well the difference. Next we're going to create a function. This function is going to be outside both of our classes. And I will just remove the space in here. I'd like it to be more tight in here. I'm going to define the intro introduce. I will send in the character that we'd like to introduce and we will simply return character speak. There we go. Add a few extra lines in here. I'm going to say Harry is equal to a wizard, and he has the name Harry Potter. Harry Potter. Then we will print out introduce. Then we will send in Harry. Then I will select this and duplicate it or pasted in here as well. Another will have her mine out her ion knee and she will be a witch. Her name, some people thought her name was Hermione before the movies came out, which is funny in here. We'll have also and his name will be Ronald Weasley. We need to also print out Hermione and run Wesley apparently is written incorrectly. I mean Weekly Wiley. I don't know. I think this is how you write Wesley. But anyway, in here if I write Click and I run, look at that even though we're calling the same function. Let me jag this over to the side. It's not allowing me. There we go. Even though I think all right, seems good. Look at that. Even though we're calling the same function on our characters, we are getting different outputs. This is basically polymorphism where we are using the same function but getting different behaviors. We have the same method being called, which is the do speak, but getting different behaviors from this do speak. I just noticed changes to a small W. There we go. So as you can see, speak used on Harry, used on Hermine, but it has different outputs. And that's the basics of polymorphism. Nothing too complex, obviously, when you start using it in real world scenarios, it can get a little bit complicated, but as a concept, it's easy. Before we continue on, let me provide you with a bit of a challenge to add Muggles. Add another class which will be Muggle. It should have the in it with a name that you should provide it with and a method to speak. Then create a Muggle object and introduce the new Muggle. And add an extra method which would be cast spell to all of our classes. Pass the video right now and go do the challenge. Hey, welcome back my fellow Python programmers. In here we're going to create a new class which will be Mule. We'll define the in define the in it. We'll have the name and we'll say self underscore name is equal to name and we'll define the speak. I will just copy this. Wait, wait, copy this based in here. Too many spaces. Well met. I am and I am a muggle. Boom, there we go. He's just a muggle right here at the bottom. I'm going to create a new mugele, which will be Emma, and we'll say that she's equal to a muggle class, and she's Emma Watson. Go figure with a big upper case. I will print out introduce Ma. If I right click on it, should be obvious that, there we go, we get a different, oh, let me just change this. I have a hello. Okay, I will say Hi, my name is just. So we have a little bit of a different output, a different word. So we can easily distinguish between the classes using the speak method. There we go. That's polymorphism. Now we said there is also the part of the challenge where we need to add an extra method, which is cast spell for the wizard. I'm going to define cast underscore spell. It will just take in the self and we will return self name plus cast a spell when, I have no idea if that's how you write it, but I'm sure that it's, it's Laos. Anyway, we will copy this and give it to the witch as well. Actually, let's do something fun. And here we'll say two big S. Okay? And then we will copy this and give it also to the muggle. What should the muggle do with a casting of a spell? It will just say must cast spells. What's the right there we go back. Make it into a special character. We don't need the return. And what does it say in here? The spell may be static. All right, that's not an issue here. I'm going to have a print, I'm going to do the following. I will print out, and we need to define cast in here. Send in the character. Character cast. Character. Okay. What's the issue in here? Why is it not giving cast underscore spell? Okay. No suggestions. Not a problem. Maybe it's just not recognizing that character is one of these. That's okay. In here, I want to print out the following. I will print out cast Harry, her Ron. If I right click and I run Harry Potter cast Leviosa when Guardian Leviosa was cast by her mini ranger. And then Ron Weasley cast another Leviosa because he's a wizard, so he has no idea how to cast Leviosa. Then unfortunately, Emma tried to cast a spell as well, but she's a mule so she cannot do it. I hope you understand how polymorphism, or understood how polymorphism works. It's not too complicated. It's just a way of using or naming our methods the same in different classes. I mean, that's the surface level comprehension in here. But it's a very important concept to know when it comes to object oriented programming. Thanks so much for watching, I hope you enjoy. And in the next video, we are going to be looking at composition. So we're going to see the difference between a and has a relationship. We will see you in the next video. 101. 16. Composition: Welcome back my fellow Python developers to a brand new video where we are going to be talking about composition in Python. And composition is obviously also available in any other programming language that has object oriented programming. That's why I told you this is a very important section. Once you understand object oriented programming, you can then delve into any other language if you ever need to in the future. What is composition? First of all, composition in Python is a way to create complex objects by combining simpler objects. What do we mean by that? Basically, it's a class composed of other classes at its attributes. Meaning that an object of one class contains objects of another class. Read that again. Listen to that. Again, understand it properly. Because inheritance is a relationship. Meaning that the Orc is a enemy. But the composition has a relationship. That's why the class component of other class, a class has its attribute as another class. We're going to see what that is basically. Let's say or has an enemy or, or has a club. That would be a composition relationship. It or allows us to model real world relationships between classes and objects. And it also helps make the code easier and more dynamic. Let's go back to our wizarding example in here and look at what we can do to create this has a relationship. So we're going to add a bond class to our classes. Example, since we have a wizard and every wizard or which has a want, let's go down in here and I'm going to create a class in here. I'm going to say class wand. And did I seriously add parentheses? And I'm going to define the in it. And we're not going to have any names, we're not going to make this too complex, I'm just going to say that self dot underscore w is equal to Holly and then self underscore core is equal to Phoenix feather. In here I'm going to define underscore one actually just use because this is a one that can be used. And we will return made of plus self wood with plus self core core. There we go. We'll add an extra space in here. And then we will go back to the wizard right here under the name, I'm going to have underscore wand. This wand will be equal to the wand class. We can cast a spell. We can, we can also use want with just a self in here. And then I will return self name first of all. Okay? Or use a want or uses, because the want chooses the wizard, not the other way around, self want. There we go. I'm going to go back into our main code. We have the main code right here. I'm going to add a print even though this output is getting a little bit long, but that's okay. Where we have Harry, we're going to print out Harry want. So when I write, Click and I run, this is what I get. Harry Potter uses want or a want made of hoy as wood, with phoenix feather core. So as you can see, we have a class want and we have an attribute in the wizard that is of type want. So this is a, has a kind of relationship where the inheritance was, is a kind of relationship. If you're still not sure, think about the has a, is a relationship type. I'm going to issue you a bit of a challenge that may help you understand this better. So Wizards also need a house. So create a house class for the four houses in Hogwardshd. They should have only one attribute, which is the name of the house, and make the name Griffin Door. Just set one name. If you want to delve deeper again, if you want to expand this example, I would love it and please send it to me. Show me how you expanded the lesson. But for now, just make it Griffin Door and create a getter that returns the house. Mm hm. If you remember what that is, add a house attribute to the wizard class and try to print it out if you want as well. So posit the video right now and go do the challenge. Okay, welcome back. How did you get on with that? Under want again, in here I will create a class that is house. Define the in it. Nothing will be in here. And we'll just say self name equal griffin. Do. There we go. And we're going to define get, underscore house, underscore name. This is the getter that I told you about. Not the getter in the sense that it's a very complicated getter, just a very easy, normal getter. We will return self thought, there we go, back in the wizard, we're going to have self underscore house, which will be equal to house. Now the wizard has a house and we'll define a method that will get us the house info. We will simply return self dot name plus belongs to house plus self dot house. And is that correct? Set dot house dot get house name. Of course, because we need to return the house name as well. There we go. Everything in here is set. So I will scroll down to the bottom and in here print out Harry dot get house or Harry dot house house info. Yeah, there we go. So if I write Click and I run look at what I get. Let me just make sure. Okay, let's expand it. Harry Potter belongs to House Griffin door. So as you can see, this is composition where a wizard has a wand. Where a wizard has a house. So it's has a relationship there. We got nothing too much in here. So, ladies and gentlemen, I think this might be the end of the video of the section. Later on, I believe I'm going to expand on this because I really love object oriented programming. We will delve deeper. We will learn more later on when I update the course. But for now, I hope you enjoyed. I hope you understood. I want to congratulate you on getting to this video. You completed section number, I don't know. So congratulate yourself. You are now top tier. You know how to create classes, you know how to manipulate objects, you know how to create inheritance. You know about subclasses, dynamic implementations, overriding methods. You've delved deep into attributes, into methods, into classes. You understood a lot of things. Static methods, I mean, you know so much more than when you started in the next section. I believe we are going to be moving on to understanding more data handling tools like dictionaries and sets. I'm very excited to get started with that section. Thanks so much for watching and I will see you later on. Bye bye for now. 102. Section 8 - Dictionaries and Sets | 1. Dictionary 101 : Welcome back my fellow Python programmers to a brand new video and a brand new section. In this section, we are going to be exploring dictionaries and sets. We're going to start off with dictionaries first. What are dictionaries? A dictionary is a collection of key value pairs. This is very important to understand. We have keys and we have values. And they are paired together and put inside of dictionaries in order to create the items. Each key value pair in a dictionary is separated by a column, and all pairs are enclosed in curly brackets. Just like we've learned lists where we had square brackets around the list in this situation or with topples when we had round brackets. In this situation we have curly brackets. And obviously we're going to have a lot of examples showing this, but you have to know this first. And they are separated by a colon. The key and value are separated by a column. So for example, if we have my dict, which is dictionary equal to curly brackets, which I said right here, it's enclosed in curly brackets. We have the key. Look at that. The key could be a string, could be an integer, could be anything. In this case, it's a string because we have the double quotation marks. Then we have the column, and then we have the value one. Key one value one creates the key value pair and it's the first item in the dictionary. Then we have a comma, and then we have key two, value two separated by a column as well. And the key in this situation is also a string. The value can also be anything that you want. It could be an integer, it could be a string, it could be any object that you want. The key is like a label that you can use to retrieve the corresponding value. For example, let's say I can or I have this dictionary, my **** one, value 12, value two. I can use key one in order to retrieve value one. And you'll see that this is a very useful way of retrieving information. It's much more efficient and much faster than using lists and tupples. Keys must be unique and immutable. These are two very important keywords here, unique and immutable. For example, keys need to be strings, numbers, or they could even be topples. While values can be any data type, the value can be anything that you want. The key should be unique and immutable. I might have said it could be anything you want, I apologize for that. It needs to be unique and immutable, meaning that you can't have the same key appear twice. You can't have key one and then have key one. Again, it will not cause an error, but we'll see through some examples that it will ruin the effectiveness of the dictionary. Finally, you can access the value of a specific key by using the square brackets over the brackets with the key. For example, my dictionary open up the square brackets, send in key one and then you should get the value one in return. I know this is a bit complicated, especially if this is your first time looking at dictionaries. Don't worry. Focus on the main ideas. How we write our dictionaries. That we have key value pairs, that the keys are unique and immutable, and that we can retrieve the values using the key label. These are the four main points that you need to think about. But enough looking, enough theory, let's go into our code and start actually practicing dictionaries. I'm going to go back into my code in here and last time we left off on classes, maybe we left off on something different. I will keep updating this course. I don't know what will happen down the line, but for now we're going to go into file and we're going to create a new project. It's going to be Python next. This is, first of all, we need to change the location of this. It's going to be in our Python course inside the code. Yeah, there we go in here. I'm going to add another one and we'll just call it the diction, Dictionaries and Sets. If I wrote that incorrectly, excuse me. Yes. Let's go ahead and create. Let's open it in this window and we should be good to go. There we go. From here I'm going to go to create a new Python file that I'm going to call underscore in. So let's close down projects and let's go ahead and get started. First of all, we're going to create our first dictionary. Our first dictionary is going to hold the of some of our bright students. We're going to have the keys as the string names of our students. For example, Alice will have a grade of 90. Then we have Bob, which, or who will have 85, will have Charlie, 92, David, 78. And I'll actually just copy this. There we go. Notice that because David appeared multiple times, we immediately got a highlight and grace. Or before we even put grace, let me just copy this and then take it back to David. If we hover over it, we'll see dictionary contains duplicate keys, David. Okay, We'll handle that later on. But for now, let's just take it back to Grace. David will have 78, Frank will 88 for Grace. This is our dictionary. As you can see, we have key value pairs. The keys are the names of the students. The value is the grade that that student has. The key should be unique, as we saw just a bit before, the key should also be immutable, meaning a string and integer, whatever the value could be, anything that you want. Let's go ahead and try and access some of our grades in here. I'm going to say my underscore grade is going to be equal to grades. Open up the parentheses inside will have Bob and then we'll print out my grade. And we'll print out David's grade is two dots come up grades. David what we're doing in here, just like we said, we're trying to retrieve Bob's grade using the label of that key value, which is the key. We're using the key. And keep in mind because this is a string reference and we're using that exact label, upper case and lower case matters in here. If we just variety click and look at that, there is a key error, meaning that there is no inside of grades. But if I use the upper case, there we go. You can see that we retrieved Bob's grade, which is 85. We printed it out. And we also retrieved David's grade, which is 78. And I added an extra space in here because I'm using two arguments in this print. Keep that in mind. We're not using the F type for the replacement fields. As you can see, dictionaries are something new, but not completely new. If you understood how lists work before, this shouldn't be that far from the same logic. The only thing that might be a bit complicated is the key value pairs. We'll see that there are a lot more exciting things that happen below the surface that we can use to manipulate. But for now, I have a challenge for you, and your challenge is to get our values differently. First of all, access the grade of Charlie. We want to get Charlie's grade, use the get method. And I recommend that you go through three schools to get that. Get it. The ponds are infinite here. Oh, okay. Look it up online and check what difference it makes on W three schools. Why do we need the get if we already have the normal square brackets? I want you to tell me why. Why use one or the other. Pause the video right now and go do the challenge, okay? How did you get on with that? I hope you understood how we use the get in here. I'm going to get another underscore grade. If I can type it out, another grade is going to be equal to grades. Get, and I'm going to get Charlie's grade. I will print out another grade. And if I write, click actually, let's use this. Let me just copy this. Paste it in here. Add a comma, and we'll see Charlie is great. Right click, Run. Boom. There we go, 92. If we look at the grades, that is correct. But before we need to move on, we need to understand the difference between these two methods. And I hope you tried your best to understand why we use the get. Keep in mind the keys here are case sensitive. We've already covered that because these are string references for our keys. Remember, our keys are unique, so need to be different than each other, which means that case sensitivity here plays a role. What I mean by that is if I change this from a Charlie with a capital C to a Charlie with a capital C H. And what do you think the output is going to be? Now if you've went through the get and understood what it does, you'll know that it simply returns none. How is this helpful? Well, because remember when we changed from a big B to a small Bob, we did not get none. We actually got an error. Basically what happens with the get, the get allows us to try and access these key value pairs without creating any errors in case it does not find the appropriate key in our dictionary. Also, keep in mind that indexing can be slightly faster than using the key. When I say indexing, I mean using the square brackets because it doesn't involve any method calling. It's not going to matter too much in our case because these are small changes in the milliseconds. If you're accessing a key many times in a loop or in a performance critical section of code, indexing might be a better choice. But it could also come with it. Drawback in case there is, or the key that you're looking for is unavailable. If you know what the key is, using the indexing is better than the dot get, but dot get is safer and that's how life works. If you want risk free, you need to be slower. If you are a huge risk taker, then you will go faster, you choose your path. I know it's got Phil, very philosophical for some reason anyways, thanks so much for watching. I hope you enjoy it. And in the next video we're going to be looping and iterating over dictionaries. I hope you're excited for this section as much as I am. Honestly, it is kind of boring, but learning how to manipulate data using dictionaries is imperative. So I will see you in the next video. Bye for now. 103. 2. Iterating over a Dictionary: Welcome back my favorite Python developers to a brand new video. And this one, as I told you, will be looping or iterating over dictionaries. Now, this section is going to be a little bit hard. It's going to be a little bit dry, but as I told you, it's very imperative. So I decided to lighten up the mood. I'm going to start this lesson with a challenge. Immediately. How cool is that? Right? You're probably hating me right now, but you still need to create a simple for loop that iterates over the grades dictionary. So we're still in the same file. We're still going to iterate over the grades dictionary and print out the value of each iteration. For a second, try to imagine that grades is just another list and you're trying to iterate. And you're trying to print out whatever is being given to us, test it out, see how it works, and I will see you in just a bit. Okay. How did you get on with that? I hope it wasn't too hard. First of all, I'm going to take back Bob Bob to a Big B. Very nice. I will add a print in here. I'm going to say four key in grades. Print out the key. I know what the output is going to be, that's why I call the variable that we're using to iterate over the key. What we're going to get and what you probably got as well is all of our keys. Notice when you iterate over a dictionary, you are iterating over its keys. If you want to get the values, you need to do the following. And it's pretty simple. We need to add a common, then grades, and then we can simply use the key. Notice that I can use the key directly. Of course, I'm not going to add these two quotation marks around it. Because this or this means that we're trying to look for the grade that has the key key, like literally the string key as its key. If I do that, I'll get an error because there is no grade with the key key, it's a bit confusing. Just know that we need to do this when I read, click on, boom. There we go. Look at what we get. But this is not clear, so we're going to use the Sp equals to this. This will add a separator between the different arguments that we provide our print function. And this is the output that we, as you can see, we've printed out our dictionary. Pretty simple, nothing too much to think about in here. But there is a better way of working with dictionaries and getting information out of these dictionaries without having to, first of all, get the key and then use the key to get the grades or whatever. We can do it in a much more efficient way. First of all, I'm going to comment out these two lines, select both of them, and hit control forward slash. Then in here I'm going to say four key value in grades, items inside, I'm going to print out the key value p. Then, okay, there we go. The print should be pretty simple in here. We're simply using the key, the value, and we're adding a separator so that we get the same output as we had in here. The only weird thing, but it shouldn't be weird to you because we've already went through all of these sections, is how we're creating this for light here. As you can see, we have the key value in grade lot items. What are we doing in here? I can hear everybody saying we're unpacking a topple exactly. So this looks exactly like when we were using the enumerate. And the enumerate returns two items to us. It returned the index, and then it returned the value associated with that index when we were working in a list or a couple. But now it returns the key, and then it returns the value. If you remember, if you go back and learn what we did in the enumerate, you might recall that I did not say it returns the index. I said it returns a number. I was very specific about it, and that's why I was specific about it, because it doesn't always return the item. It might return a key. And that key could be a string, it could be a number, it could be in whatever. Oh, sorry. That key should be something unique and immutable. Basically, the grades item item returns an object that contains a list of the key value pairs in the dictionary. When I write, click and I write, and I run, there we go, I get the same output being printed out. So that's basically it. This is how you can iterate over a dictionary using the items. Or you can simply access the keys and then use those keys to access the dictionary values. But obviously, the dot items is much more efficient. I hope you enjoyed. In the next video, we are going to be appending items to our dictionary, so we'll see how we can add an item to our dictionary. I hope you enjoyed and I'll see you in the next video. 104. 3. Appending items to a Dictionary: Welcome back my favorite Python programmers to a brand new video. And this one will be appending items to our dictionary, meaning we'll be adding items to our dictionary in various ways. And we'll see how having two keys that are the same can affect the way our dictionary behaves. First of all, we've seen that we can create a dictionary using a literal meaning that we can literally set it up with elements. For example, in here, I can come in and I can add, let's say Philip. And Philip would have a grade of 12. Philip hasn't been studying. Well, but we can also add a grades, or people with grades, or students with grades using a different way. For example, in here at the bottom, or not actually at the bottom. I'll add it directly above Bob. In here, I'm going to say grades, open up the square brackets and I'm going to say Henry equal to 83. Now when I write Click and I run, you'll see that at the bottom I get Henry. So keep in mind that we added Henry at the end. So when we add to a dictionary, okay, outside of the actual dictionary, the order of insertion is preserved. Or the insertion order is preserved, meaning that we add only at the end. Now you'll see in here that we have some kind of warning if we hover over it. What does it say? This dictionary creation could be rewritten as a dictionary literal, So it means this one. Now, let's try to show action and replace dictionary creation. Uh huh. Okay, there we go. So you'll see that it created or made the dictionary horizontal and added Henry at the end right here. I'll just take it back because we are trying to show you, or I'm trying to show you how we can add items in various ways to our dictionary. But let's continue on. Let's see what happens if we try changing a value under Henry. I'm going to try and say grades, open up the square brackets and then Axis, David. And then I'll say that David's grade now is 88. So remember a David's grade was 78. We can even see it right here. But now if I write, Click and I run look at that. David's grade is 88. So something to keep in mind is that every key is unique. Otherwise, how would we know which one we are changing? What if we had two David's inside? Which one would change? Well, that's the question you'll need to find the answer to when you do the following challenge. I want you to add a Charlie at the top of our dictionary, meaning inside of our literal dictionary. You'll need to add another Charlie. We already have one, add another one. Give a grade different than the second one, provide Charlie with a different grade. And what I meant is, at the top of our dictionary, that's why I said give a grade different than the second one, because Charlie is like the third or fourth person anyway, give him a different grade. And what happens when we actually run the code? First of all, I want you to think of what would happen, and then I want you to test it out. So pass the video right now and go do the challenge in here. I'm going to go to the top and I'm going to add Charlie, it should be a string, Charlie, two dots. And I'm going to give Charlie a grade of 50. Notice that immediately, we have warnings in here telling us that this dictionary creation could be rewritten as a dictionary. That's the old warning. If we hover over this warning, it says that dictionary contains duplicate keys. Charlie, if we run this, we're not going to get an error, obviously, because it works. But we do have something happening in here. We have Charlie at the top, which is where we've added Charlie, but he has a grade of 92 instead of the 50 that we provided. What is happening in here? First of all, it's very obvious what's happening. The key preserve preserves its location, but the value changed. The key position is preserved, but the value changes. If we have two keys that are the same in the dictionary, it behaves as if we've changed it outside of the literal like we did with David previously. The way you could imagine it, like a small robot going over the grades and trying to print things out. It finds Charlie. It's like great, Charlie is in position number one. We print Charlie out and it's 50. Excuse me, we don't print actually anything out. It's 50. Then we go to Alice, grade Alice in position number two. Bob is in position number three with 85. Wait, Charlie. Charlie again. Oh, okay. Well, I've already seen Charlie. He had a grade of 50, but now I can see that it's 82. So we changed the value, and then we printed out. This is how the dictionary is interpreted. And notice that in here it gets to 92. So the dictionary kind of has a soul of its own. Even before printing, it already changed the grade of Charlie because it detected that there was another Charlie. And we'll see that this Sol Sol in between brackets, of course, will be very helpful down the line when we try to create different things and use it for different purposes. Thank you so much for watching. I hope you enjoyed. In the next video, we're going to be looking at removing items from a dictionary. And we'll see how all of that works. I will see you in just a few. 105. 4. Removing items from a Dictionary: Welcome back my favorite Python developers in this video. As promised, we're going to be removing items from a dictionary. Now there are many ways of removing items from our dictionaries, so let's look at a few of them. First of all, deleting from a dictionary is very similar to how we did it in lists. But in dictionaries we use the key to indicate what we want to delete. In lists and topples we used to indicate at which index we would want to delete it at. To do deleting at or from dictionaries, we need to indicate the key. For example, in here right before I print out the key and values, I'm going to delete grades at Bob. Now when I write Click and I run, Look, we had Bob. Now when I write Click and I run, we don't have Bob. Bye bye Bob. As you can see, when we run, the item is deleted. If this works so well, why do we need to have other methods? Well, to demonstrate, I'm going to try and delete somebody that's not in our class, for example. And when I say class, I mean the class that has all of these grades. Not a class like in the classes that we learned in the previous section. Just to get that out of the way, we're going to try and delete Kalen. If I write click and I run, I get an error. It's a key error because Kalin does not exist in our grades. What shall we do about this? Well, we have other ways of deleting. It's not actually called deleting, it's called popping. For example, in here I can say grades pop can provide Kalin again. Now if I write click and run, I still an error. I get Kalen or a key error where Kalin is not available. Wait, wait, wait. Didn't we just cover this? Shouldn't this be like the solution to all of our problems? Well, it is, but you need to provide it with another argument. For example, in here you can tell it in case you do not find kalen or a item with the key kalen, you can just return none. So now when I write click and I run, you can see that there are no errors in here which is perfect. But we don't only need to return none, in case we don't find anything, we can return absolutely anything that we want. For example, I can return a nine. There we go. Well actually it's not printed out because we need to actually print out. Or we can say for example, Lens or Kalin. Underscore grade equal to grade pop in here. We can print out kalen grade. I'll actually just add a small print in here just so we can separate it. There we go, We get nine or we could have just printed out none. There we go, we get none or we can say sorry, no one. No one. Is that how you write? No one. No one with that name in our grades. Right Click, run, sorry. No one with that name in our grades. All right, So using the pop is a great way to avoid getting errors and also to be user friendly in case the user is, let's say, looking for his son's grade or something, or a student looking for their grade. You can use the pop in order to send them a message. You're not even here or I don't know, maybe you're looking for a different class. You can do whatever you want using the pop. Now, time for a bit of a challenge to pop two values. I want you to pop two values already present in our dictionary, for example Alice or Bob. You can try to pop those names on the second pop. Present an alternative string to be printed in case we don't find the key. Let's say you try to pop David. You also can provide it with a string in case we don't find David here. Okay, so we'll see what happens in that situation. What happens if we try to pop something and it's there. But we provided it with an alternative string or alternative thing to be output it. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? In here in the print, I'm going to add another print in here. I'm going to say Alice underscore grade is equal to the grades. And we'll have Alice and we'll print out, oh my god, Alice grade. We'll also have David underscore grade. And it's going to be equal to grades Pop David. But on my second pop, I'm going to say, we don't have a David here, backslash and one of those. Do you remember the special characters? I hope you do, because they could come in handy in situations like these. And then we'll just have David's grade. Now notice what's going to happen in here. Very important when I write. Click and I run. There we go. You can see that we get 90, which was indeed Alice's grade, and we get 88, which was indeed David's eight. What did we pop David? What do we have, David? Oh, that's because we changed it in here. Very nice. Honestly, I did not plan this, but it's good. It's good that we actually were able to find it that fast. So as you can see Alice and David, but keep in mind that they were popped, so you can't find Alice and you can't find David. When we try to print out the key value using the grades items, notice that now the values that we just pop no longer show up at the bottom. Because while they've been popped. Even though I told this before, I'm just reiterating, making sure that we understand what is happening. I hope this wasn't too hard. Removing items is not something very complicated when it comes to dictionaries. In the next video, we are going to be looking at iterating over dictionary keys using the N. And we're going to go back to one of our previous projects where we were building a car with wheels, lights, windows, and so on, and making it much better using our new found powers of dictionaries. So thank you so much for watching. I hope you enjoyed and I will see you in the next video. 106. 6. Computer Builder: Welcome back my fellow Python developers. In this video, we are going to start building various computers. How about that? First of all, we will need a list of parts and the different computer models that we can create with them. Below this video, somewhere around, I don't know, in the resources, wherever you are, wherever you're watching this or whatever different settings it's happening in, you will find a file that you can download where we have all of the computer parts and the computer models. The first thing we need to do is we need to create the computer parts content file. We'll go to file New. We'll create the computer score, underscore content, pull, hit Enter, and there we go. We're here. So I'm going to copy and paste a very long list in here. And don't worry, we will have it available to you. Once you do that, you'll see that, first of all, we have the computer parts storage. So we have ten CPUs, seven GPU's, 50 Rams, three motherboards, 30 SSD's, six monitors, et cetera, et cetera. And then we have the computer models. So for example, we have the gaming PC in here, which requires a GPU, CPU, Ram, SSD. We have the business laptop, which requires a CPU, no GPU, Ram, SSD, and so on and so forth. A home desktop, a media center, and a work station. Now, later on we will make this list a bit better, where, for example, the business laptop will require two CPUs or 15 Rams and so on and so forth. But for now, we just want to work with what we have. We are going to keep this file as the content place where we have all of the contents that we have, but we're going to create a new Python file that we're going to call the computer Builder. Inside of this computer builder, we are going to import from the computer parts content from computer part content. Import the computer part storage and the computer models. All right, now if we try printing out the computer part storage and we try printing out the computer models, we should see something like this. Boom. Go CPU, GPU, Ram, motherboard, et cetera, et cetera. And then look at that. We have the gaming PC, and you'll see in here that we have also the business laptop and so on and so forth. Something that I just noticed that I forgot to mention is that we have the computer models as a dictionary, which has the keys as strings. And then the values are lists. We've never seen this before. It's a list of strings. The value is a list. It's not an integer or a string, it's an actual list. Look at how deep we can go with data handling using dictionaries. In here, the computer part storage is a dictionary, the item or the part as the key being strings. And then the value is the amount of these items that we have. So back in the computer builder, I'm going to drag this and set it to the bottom. Maybe it looks better. So there we go. We have the CPU GPU, et cetera, et cetera. But now you have a challenge in front of you, and your challenge is to display all of the models. Create a for loop. Use it to enumerate over the computer models and print out the index and the key. We should have something like this. There we go. Keep in mind I want you to now not use the items I want you to enumerate over the computer models. Because we want to see what we have and we want to get this kind of output. Make sure that you do that. Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? First of all, I'm going to comment these two lines out. These were simply for debugging, making sure that we got the correct data. Then I'm going to say four index key in enumerate. We're enumerating again over the computer models in here. When I said get all the models, I'm sure some of you are very excited. But it turns out that no, we're not those types of models. I'm going to print out the index key separator, and the separator is going to be the two dots. This is basically it. This is what we wanted right now. When I write, click and I run, this is what I get. Zero for gaming, PC, one, Business Laptop, Home, Desktop, Media Center, et cetera. But in fact, we want to have a separate dictionary that displays the different models we can create. I'll tell you, I'll not tell you why it will become more evident later on. For that reason, I want to do the following. I want to create something called a display underscore dictionary, and it's going to be equal to this empty dictionary. Then I'm going to have, or actually know what, Let's just move it. I wanted to delete it, but we'll just move it up right here. Instead of printing this, I'm going to comment this out. I'm going to create or say the display dict STR. And this was not part of the challenge, by the way, index plus one is equal to key. What the hell is happening here? First of all, let me right click and run. Nothing happens well because if we want to simply print out display dict, right click on one. Look at what happens. Now we have one being the gaming PC, two being the business laptop, three being the home desktop for media center, five, the work station. What's happening in here? As you saw before, Maybe I should not have commented this out. Just so you can see that the index is zero. For the gaming PC, we use this index. We add plus one to it, and then we turn it into a string. And then we use this entire thing in here that we've created as a key to add it to the display dictionary. By saying it's equal to the key, we're calling it a key because it was a key right here, gaming PC was a key and now it became the value. Notice again, if it's confusing, let's think about it again. We had the computer models, we had the gaming PC was the key, the business laptop was the key in the computer models dictionary. Then what we did is we enumerated over the computer models, we had gaming PC at position zero or at index zero. Business laptop at index one, Home desktop at index two. Media center at index three, workstation at index four. But we know that in a dictionary, we don't need to have them starting at zero. We would prefer to have the gaming PC start at one. For the same reason why we would use zero right here to finish. Maybe we would like to use zero to finish. What we did is we created a display dictionary where the key is now the index from the previous dictionary that we had. Look at that. Now gaming PC is at one, business laptop is at two. Now, later on, if we want to build a PC, we can say that we want gaming PC. By clicking one, we would get the gaming PC. We would use that in the dictionary of the computer models to get, for example, which computer parts the business laptop needs. If you're still confused, I recommend that you go over this a few more times to properly understand it. The most important thing that you need to know is why we used the enumerate, which was to get the indexes, and then how we created the display dictionary, which is right here. Which is this right here. Your time. Don't worry, this is not very simple. I know we're getting into the more complex parts, but it's very important to understand data handling using dictionaries. But now we also want to print out our choices in here, I'm going to say, first of all, I will comment this out and I do not want to print out the displayed dictionary. I will comment it out as well. In here I will say, while true, this will be to display the menu. Why do I get an error? And then expected. Okay, okay, we still haven't written anything in here. When I print this should go away. Good. So I'll say please choose your computer model. This was part of your challenge. Even though you did not have to do it like I did, you did not have to create display dictionary. But you should have gotten this output right here. Please choose your computer model and here I'm going to print out the dashes that I indicated, multiplied by 20 and I will say four key value in display dictionary items. I will print out replacement field, key, replacement field value. That should be it. Then I'm going to get the choice, say choice equals input. I'll say your choice like this. Maybe add a space, or maybe we can add a column. I don't know. You select whatever you want and we'll just say if the choice is equal to zero, we'll break. Because remember we're in a wild true loop. Now if I right click and I run, let me move this right here. Boo there we go. Maybe we could add a print in here just to separate the truth, or maybe we could add a backslash D. Does it look good? Not so much, honestly. I think the back would serve us better right here. Let's see, I don't know. Honestly, I don't know. Yeah, there we go. I think this is good. I don't know. I'm not sure. Anyway in here, what's your choice? One gaming. Pc. Boom. 23. Okay, we're not getting anything useful yet, but at least it's working. I hope you understood, I hope it's not too confusing. Again, next video we're going to be looking at multiple dictionaries. So it's very important that you understand what we did in here. Because the next video, we're going to use what we did in here. If you're worried about who this is getting too complex, Michael, what the hell is happening? Don't worry. Breathe, Take a deep breath. Things are going to only get harder from here. No, I'm kidding. Everything is going to be easy as long as you focus, as long as you understand, and you take things step by step and slowly build. Also, we're always available. You probably have my numbers somewhere. You probably have an instructor's number somewhere. Don't hesitate to contact them and we will help you. I will see you in the next video. 107. 5. Iterating over dictionary keys using `in`: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be iterating over dictionary keys using. The main goal in here is to understand how we can iterate over dictionaries using the n. But the other goal is to also understand which data structure should we use, a dictionary or a list when we come up into a situation like this. When I say this, I mean a few sections ago, a few videos ago, we created a car dealership where we had a list of available parts and we had numbers attached to these parts. Well, it was the indexes, and we would add wheels, lights, front wing seats, and so on and so forth. I hope you remember what I mean. Unfortunately, in this current project, I go back and find it. I'm sorry for that, but you can definitely go find it in the lists and pupples. Or maybe I called it car builder, I called it car dealership. Maybe I called it by car. If I'm not mistaken, it was by car. But in any case, try to go back and find it in that project. First of all, we used four loops in order to create it. Then we upgraded it using lists. We made it better using a list. Now we're going to do the same thing where we are going to make it even better, but this time using dictionaries. First of all, I'm going to go into file new and create a new Python file. That's going to be the by underscore car, underscore dict, indicating that we are using dictionaries in here. I'm going to create the available underscore parts and it's going to be equal to the following. First of all, we'll have 12 dots. Then wheels duplicate this, we'll have lights duplicate this, we'll have the front wing duplicate this. We'll have, oh my God. We will have the seats. Duplicate this. And we will have the window, window. And duplicate this again. And we'll have the stereo. Obviously, we cannot have duplicate keys. They all should be unique and should be immutable. 56. There we go. In here I'm going to create the current choice. We'll have the current underscore choice equal to none, while the current choice is different than or equal to zero, because remember zero is where we finish. We're going to say that if the current choice is in the available part, then the chosen part is going to be equal to the available parts at the current choice. And we'll also print out adding replacement field chosen part. There we go. Also, of course we need to get the current choice of, the current choice will be equal to an input which is going to be your chosen part, two dots. And then we will just select a number. Now if I right click and I run right here, you can see that your chosen part, if I hit one, for example, and hit Enter, you can see that I'm adding wheels. If I hit six and hit Enter, you can see that I am adding stereo. Do you remember how hard it was to get to this point when we were using lists? Look at how easy it is. Now we simply created the available parts. Each part has its own key attached to it. And for example, if I press nine in here and hit Enter, there you go, Nothing happens at all. So how cool is that? But very important thing to realize is when we are using the on a dictionary, we are going through its keys. For example, if I try to add windows or window, look at that, it does not work. If I try to add wheels, it does not work when we are using the with a dictionary. Unlike lists, we are looking only through the keys. That is a very important distinction, not through the values. I hope you understood. I recommend that you go through the code a few times to make sure that you properly get everything. And when you do, you have a challenge in front of you. You will need to print out all the parts. Create an L for when the current choice is not in the available choices, iterate over the available parts using the items. And get the key and part, meaning the value of the key, and print them out. Display them in a way that the user understands. Basically, right now, you'll see that we are not displaying to the users what options they have when they want to add a car or car item or whatever car part. So you need to do that using the items on our new dictionary, which is the available part. Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? It shouldn't be too hard. Right here, we're going to say L, meaning if the current choice is not in the available parts, we're going to say L, four key part. In available parts, items, I'm going to print out the key part and then separate using the column. And also we need to print out in here zero to finish. Basically what we're doing again, remember the items gives us a list of topples, which are the key part. And then we unpack them into the key and the part. And we print things out with the zero to finish. Now when I write click and I run, look at that, I get one wheels, two lights, three front wings, et cetera, et cetera. Do you I recommend that you go back to that code and you check out how hard it was to do all of these things. Look how easy it is right now. Also something to keep in mind before we move on is these two lines right here. We are not worried about using the wrong current choice inside of our available parts. Because remember, if we use a key that's not in our dictionary, we can cause an error. But because we're using the if current choice in the available parts. So first of all, we're checking if our choice is one of the keys that are in our dictionary. So if it's 12345 or six only then do we try to access one of the values inside of there. This is something very important to keep in mind. In summary, when should you use a list and when should you use a dictionary? Well, obviously, it depends on the situation that you're in. You should use lists when you need to maintain the order of elements and access them by position and use dictionaries when you need to access the elements by keys or need to store key value pairs. If you have something where it's very important that you maintain the order, go ahead use lists when you have something that is a bit more complicated and you'd like to have key value pairs than the dictionaries are the way to go. Finally, before we move on, we need to actually add the items that we try to. Well, get in here, the chosen part we print out that we are adding. This is not true because before we print out that we're adding, I'm not going to leave this. We have to check if the current choice is in the car parts already. We need to first of all, create these car parts. We're going to create underscore parts, and we'll say that it's equal to an empty dictionary in here. I mean chosen part, not the current part. If the chosen part is in the car parts, then I'm going to go ahead and print out removing the chosen part. How do we remove an item? How do we remove an item? By using the pop, even though in this case it's going to always be inside of the car parts, but being extra careful never hurt anyone. Also in here we're going to add an L and we'll say that we want to, we're adding then car parts. Current choice equals chosen part. What else do we need to do? We would also like to maybe print out our list. We'll print out your dictionary now contains, we'll just print out everything. So we'll print out our car parts. Right click and run. Let's add wheels. Boom. Now we have one wheels to boom, lights to boom, and lights were added on top of it. That's because, oh, I apologize. This should be indeed the current choice because again, this was a mistake that I made. I could have edited this out, but I would like to keep it because at first I did it correctly, then my mind was still in the lists part right here. Current choice should be used instead of the chosen part. Because remember when we use in, we are iterating over the key. We're checking if the key was already there. Now when I write click and I run, for example, I add wheels, I add lights. I want to remove the lights. I hit too, and there we go. Now it gets removed. When we were trying to use the chosen part, it was a value, the chosen part was lights. So we went through our dictionary and we didn't find lights in here, so we did not remove it. So I hope you understood, for example, three front wings four. If I tried to add another four, you can see that it gets removed. We add seats. We then remove seats. So I hope you enjoyed it. I hope you understood. I hope you appreciated that I kept the mistaken side because maybe some of you did it, maybe some of you did not understand why we turned from a current choice to the chosen part and then back. I think this is worth keeping. I hope you understand. I hope you appreciate the transparency that I'm trying to show here. And I will see you in the next video where we will apply this knowledge to create a computer builder project. I will see you then. 108. 7. Multiple dictionaries use: Welcome back to my favorite Python programmers. In this video, we're going to be using multiple dictionaries together to get the data that we need. First of all, we want to display the item that the user selected. Right here, you can see that your choice is we press two and then we just get our computer models. What if we wanted to actually show the user what they selected? Let's go ahead and do just that. Under where our choice is checked. If it's equal to zero, I will add an L. If in here, sorry, I will add an L. If in here LF, the choice is in the display dictionary. We are going to go ahead and say that the selected underscore item is going to be the display dictionary or the choice in side. And then we will simply print out you have selected and then replacement field and the selected item, there we go. When I write click and I run, and I want to also maybe add something in here, maybe like an extra space. Maybe a space in here. Print out just an empty print, right click, and I run your choice. Let's go with the three. There we go. You have selected Home desktop. Maybe two dots in here would be good. Then if I hit one gaming. If I hit six, there we go. I get nothing. I just get everything displayed to me again. If I hit zero, I exit out perfect. Our program is working perfectly well. Now, before we move on, we want to do one more thing, and that is when we actually select a computer, let's say the gaming PC, We want to print out all of the components needed to create or to build this computer. So I'm feeling tired, I'm feeling lazy. I've recorded for such a long time today. That is why I'm giving it to you as a challenge where, yes, you will need to display the needed components. First of all, print out the components needed. Well, that's just a broad challenge. You'll need to use the computer models dictionary we've imported, and get the component using the selected computer model as the key. If you remember, we created the selected item. This can be used as a key on the computer models dictionary in order to get all of the components. Good luck. This is not easy. But trust me, if you can solve this challenge, you are on the road of complete data handling mastery using dictionaries. So please take your time, do your best, and I will see you in a few seconds. Welcome back. How did you get on with that? Our goal is to get the components needed. In here, I'm going to print out the following. I'm going to say that we are checking components. Components needed, three dots. It's like we all were checking. We're going through so many things. Now, components is equal to the computer models. We're going to use the selected item, then we'll print out the components. If I write, click and I run your Choice one, look at that, look at that, your gaming PC, checking for components needed. Cpu GPU D, HDD motherboard cooling, and a case, if I wanted to get a workstation, then I would need CPPD, HDD, power supply, motherboard, everything the same as the gaming PC, but I also need a monitor, a keyboard and mouse. I hope you did the challenge. I hope you tried your best. Before we leave, let me just re, explain what we actually did in here because some of you might be still confused. First of all, this should be obvious by now The way we created a display dictionary, where we get the following, then the user selects one of these computers that we have, one of the computer models, for example, they select four. When they select four, so right here, the choice is four. We check if the choice is or is equal to zero, then we break out. If it's not, we check if the choice is in the display dictionary. If it's not, then we go back through the wire loop and we print it out again. If it is, then we create something called the selected item, which is going to be the display dictionary at the current choice. For example, if I press two, then the selected item is going to be business laptop. If I press four, then the selected item is going to be the media center. This is how we created the display dictionary. If you're not sure how this works, go back to the previous video. Then we say, we want to print out you have selected et cetera, et cetera. This is where the output we get then checking for the components needed and this is where we get them. Now the more important part is when we use the selected item as a key on the computer models to get access to all the components. For example, if we selected the media center, then we use the media center. The selected, let's say we selected four. The selected item is now media center. We use this media center, we feed it into the computer models dictionary right here on the computer models. We scroll down media center and we get CPU, Ram, SSD, power supply, Blue Ray Drive, TV turner. What? Tv Turner tuner. Tv tuner and remote controller. Okay, so I think I explained it as detailed as possible. If you're still unsure, rewatch the video, make sure that you understand everything. Because in the next video, we are going to be looking or checking for computer parts. We're going to be expanding on our storage. Expanding on what each model needs. Please go back, make sure you understand everything, even if it takes you more time than you think it's worth, trust me. Once you understand it, data handling skills will go through the roof. It's imperative to understand dictionaries. No career that you will go through will require you to not use dictionaries. You will always have to use dictionaries in some form of way. Thanks so much for watching. I hope you enjoyed, and I will see you in the next video. Where we will be checking and going deeper into computer parts even. 109. 8. Checking the computer parts: Welcome back my fellow Python developers. In this video, we're going to be checking the actual component parts. Meaning do we have the parts required for this specific build, for this specific computer model, I mean, or do we not have these parts? And then we will upgrade our dictionary so that we also can see how many parts we need, Meaning that we might not need just a Ram, we might need ten Rams or 60 SSDs or whatever. So basically, the goal of this video is going to be to expand our project. And while doing so, expand our ability for data handling using the dictionaries that we just learned. So let's go ahead and get started. First of all, we'll need to type in the following code that will tell us whether the item that we're looking for is available or not. Someone here, I'm going to say four components or component underscore part in components, we're going through every single component. If the component part is in the computer parts storage, there we go. We're going to print out back replacement field computer is available and then else we'll print out backs, you don't have the necessary part, we'll tell them which part they don't have. Boom, there we go. Maybe I should move this more to the right side so that we can clearly see what's happening in here. We've got our components from the last video. Now we use these components, we iterate over them, and we check if those component parts are in the computer storage. Remember the computer storage is this, right Here we have the key. Remember, when we do we go through the keys? We've learned that in video number maybe five. And if the component part is there, then we say it's available. If it's not, we say that we don't have that necessary part. If I write click and let me make this bigger. So one boom, let's see, the CPU is available, GPU is available, everything is available, nice for a gaming PC. Let's try the Business Laptop. There we go. You can see that we don't have a battery, we don't have a display, and we don't have the touch pad. A few things are missing in here, but now it's working. But obviously, I said but too many times, but obviously that is not enough. We need to check the quantities as well. First thing we have to realize is that the models don't specify how many of each component we need in order to build the computer model that we want. Meaning that we don't know how many Rams does a business laptop require? Does it require more Ram than the gaming PC? Probably not. So we need to check for those things as well. So adding them will be easy. Very easy, of course, because right here we can simply just add an extra item or do something. I don't know, adding them will be easy. The hard part is knowing how and what data handling tool to use. For example, would we want to put this or make this into a list of couples, you know, with the CPU having a number next to it. Maybe we would like to make it into a instead of a list. We can change it into a dictionary. Maybe we would want to use sets. So what would we want to use in this case? I'm going to update this list and I'm going to use dictionaries. You will have a file with all the necessary information. I'm just going to copy this and paste it right here. There we go. You can see the computer model. The computer models dictionary. You can see that it's made out of the keys which are the computer models. Each model key has a value that is a dictionary. And that dictionary contains the keys as the components, with the value being the required quantity of set components. For example, we need two CPUs. For our gaming PC, we need four GPUs. For our gaming PC, we need 16 Ram, we need two SSD's, two HDDs, et cetera, et cetera. Now please, some of you might be. White Point? No, we don't need CPUs. There are different kinds of models, whatever. Listen, let's just stick to this because we will need to create a way to handle the data that we have. We don't care right now about the accuracy. We care more about our ability to be able to access this data and work on it. Now that we have that, you will have it somewhere under the video or anywhere around. If you have a problem finding it, please contact me Or if you're not able to download the file or any problem for that matter, contact me or your local instructor. Now that we have that, the next thing we want to do is we want to change this. Because we don't want to just print out the components that are needed, we also want to print out the quantities. We have the four component part. Now I'm going to say the required underscore quantity in components, items. So remember now when we use the selected item to access the computer model, for example, let's say it's the business laptop. The value that we get is another dictionary. The other dictionary is now the components. And now we can use the item to access the keys and value pair that are in that dictionary. We can parse them or unpack them into component part and the required quantity if the component part in computer parts storage. That's good. But that's not enough because we will also want to see if we have enough quantity. Meaning right here, if we have the necessary quantities. For that reason, I'm going to issue you a challenge to get the quantity in storage. So, use the dot get method to get the quantity we have in storage. No, to get the quantity that we already have in storage, put the value we get into a variable. And if we do not have the component, we want to check for return zero. So pass the video right now and go do the challenge. It's just one line of code. Okay, welcome back. Hope it wasn't too hard in here. After we get the component part and the require the quantity, what I'll do is I'm going to say the quantity in storage quantity underscore Underscore storage is going to be equal to the computer parts storage get. And I'm going to use the component part zero, we're basically simply axing the computer parts using the computer part, because remember the computer part here is a CPU or GPU or a Ram or SSD or whatever. We're going into the storage, we're checking this right here, We are returning the value on that key. If there is no key with that said name, we are returning zero. Why is that? Because now it's not enough that the component part is in the component storage. We have another more important thing in here. We need to check for the following. We need to check if the required quantity is less than or equal to the quantity in storage. If it is, it means that it is available. But if it's not, then what we'll do is we're going to do something a little bit different and set things up for the next video. We're going to say that the quantity underscore two, underscore y is equal to the required quantity minus the quantity in storage. Instead of saying you don't have the necessary part, we're going to say you need to buy replacement field quantity to buy of de component part. Now let's see what we can check in here. And first of all, I want you to look at the code. I want you to breathe in, breathe out, fully comprehend what is happening in here. The main points are the component items, how this became available to us, because now we have a dictionary of dictionaries in its values, how we access the quantity in storage using the component part. And also how we're comparing the required quantity to the quantity and storage. All of these things are very complicated. Maybe if you're still a beginner, it's probably like mumbo jumbo. Take the time, pause the video, rewatch it, redo it, try your own test things out on your own. Make sure that you understand what's happening. Because it's very imperative for the next video where we will be creating shopping lists. Let's test it out. Before we move on in here, let's go back to the computer. Let's see, we have ten CP used. We have anything that we can't get. Let's see, motherboards, all of them will require only one motherboard. What? Let's just try something. Let's say the Ram for the gaming PC is 16. Let's say we only have like ten Rams. Okay, so when I write click and I run, oops, I ran the incorrect one, right click and run. So your choice. Gaming PC. Hit Enter. The CPU available, GPU available, But then it says you need to buy six of Ram or six Rams. Yeah, it's going to be tricky nailing this down. Maybe just 66, whatever with an S. Let's try this again. 16 Rams, there we go, six Rams. The SSD is available. Everything is available. Let's try the media station. Everything is available. The case is available. There we go. We need to buy one TV tuner, one sound card, and one remote control. Nice. Let's see. Maybe if we use the business laptop. Uh huh. We need to buy a batteries so it's not perfect. Of course, you can create if statements, change this, change that, make sure that all of that fits correctly. You can check if one or greater than one. But the goal here is not to make this perfect. The goal here is for you to understand how this is working, and I hope you did. Please go back through the code, make sure you understand what's happening and I will see you in the next video. But one thing I wanted to add, we could have changed this from a dictionary. The value could have been changed from a dictionary to be a list of topples. For example, imagine that all of these are the same as this one. Now we could have done that, it would have worked. The only problem is maybe gaming PC would want to be modified. Maybe we want to modify it. Maybe we want to give the option to some users to increase the, increase the SSD or whatever. And we want to change it on the actual model here. In that case this would not becauses are immutable, but dictionaries can be changed. It's better to have a dictionary in this case, But a couple would work fine. Thanks so much for watching. I hope you enjoyed. In the next video, we will be creating a shopping list out of the quantity that is required to buy. Some of you are mega confused at this point. Again, as I said, take a deep breath. Please try to understand this. If you can get through this, it's very, very simple moving forward and you will have a very, very strong grasp on everything that is related to data handling using dictionaries. See you in the next video. 110. 9. Create a shopping list: Welcome back my fellow Python programmers to a brand new video. And in this one we are going to continue in our computer builder project. Now what we'll do is we're going to take all of the required quantities of the required components that we lack and we're going to be adding them to a shopping list so that they could be sent to Amazon and then the components could be bought. I don't know if it's going to be Amazon. I'm just saying there will be a shopping list that's automatically created. So let's go ahead and do that. First of all, we need to create that dictionary or initialize it, at least right here at the top. I'm going to create something called a shopping underscore list, and it's going to be equal to an empty dictionary. Next, we're going to create the function that will add these items to the shopping list. I will define underscore, underscore items or the item because we will be working one item at a time. We're going to have the data, I will make sure that it's type is dictionary. You should know how these annotations work from section number, I don't even know, a few sections back function. Then we'll have the item, it should be a string. And we will have the amount offset item that we need to buy which is going to be an integer. And we'll make sure that this function returns none or nothing in here. I'm going to say if the item in data, then I'm going to access the data, add that item, and I'm going to increase by the amount. What this does is it basically looks through the entire data that we have and checks if the item is already there. Because remember, the item, in this case is going to be the key and the value is going to be the amount that we need to get. First of all, we want to check if that key is already in the data. If it is, then we will add the amount to it. Meaning that, let's say we needed to buy one battery, now we need to, I don't know, three batteries. But the second condition is going to be L or not. The second condition, just the L statement, is going to be that we simply say, data at that key item is going to be the amount. Obviously, this is a function, so it needs a bit of space from the bottom and a bit of space from the top as well. There we go. Now we've created the ad shopping item. Finally, we need to actually start using this function. Again, I'm feeling lazy. This is a new day for me. It's still early morning. So it's going to be a challenge for you to call our function. First of all, where should we be calling this function in our code? Very important, call the function and provide the following, the empty shopping list, obviously the component part, and add the quantity that we need to buy. Finally, print out the shopping list when we exit out of the wild loop. So pass the video right now and go do the challenge. Okay, welcome back. So the first part of the challenge was, where should we be calling this function? Well, if you skim through the code, if you've understood the code from the previous videos, that's why it's very important that you understand what happened in the previous video and then move on. We're not here to win a race. This is not a 100 meter dash. This is a long marathon that we need to pace ourselves in. Where should we be calling this function? Well, first of all, in here we are checking or what the components are. So the component part and the required quantity for it. And then we're checking if that required quantity is available in the storage. If it is, then we say it's available. If it's not, we say that we need to buy this item, meaning that this is where we should be also adding it to the shopping cart. So, I'm going to add shopping item, and now I need to provide the dictionary that we want to add said item to. What dictionary is that? Yes, exactly. It's the shopping list. Next, we need to provide the item that needs to be added. What's that item? It's the component part, which is right here. That's the component that we're looking to add. And then finally, what's the amount that we need to buy? It's pretty obvious it's the quantity to buy. There we go. Now that we've called our function, the last thing to do is to actually print out the list at the end. Once we finish with all of this, I'm going to print out, I mean, I'm going to say four items in the shopping list, items, I will print out. Items. All right, we are set, I believe. Let's go ahead and test this program out. I'm going to run in here. Let's go ahead and add a gaming PC. All right, so we have everything we only needed to buy the Ram. Let's go ahead and add a workstation. All right, what did we buy? We should have bought 22 Rams. Buy one additional IC. I don't know what that is. Let's go add a media center, right? You need to buy one V tuner, one sound control. All right? I think that's enough computer models. Let's hit zero, exit out, and let's see, look at what we got here. We have Ram, additional IC 111, and the Rams are 28. Let's go and just have a small check of what if that's correct. So first of all, we needed to buy six Rams, good. Then we needed to buy 22, which makes this 28. There we go, 28 is what we have. We also needed to buy the NIC. If you remember, we checked that out, it was the weird thing. I don't even know what that is. Tv tuner, there we go. Look at that, the sound card and the remote control, look at that. These are couples funnally enough, what's happening in here is that the data that we're receiving, even though it's a dictionary, it's being given couples if you're not sure why and what kind of logic that is, let me show you. Let's try and just print out the shopping list on its own. Without anything, I will right click and run this again. 15.4 and then zero. All right, there we go. Look at what we have in here. What we're doing is we are printing out the topples. Remember we have items, and when we're doing the items, it returns a topple that we should unpack. But in this case, we are not unpacking it, we're just printing it out. That's the basics of it. As you can see, the shopping list is a dictionary. We are printing out the dot items of it. I hope you enjoy it, I hope you understood. I believe that's not the conclusion of our project. We still have one small thing to change, which is going to be adding items using something called the set default. And we'll see where that. I hope you understood everything. I hope you've enjoyed. I hope you are understanding the complexity behind data handling using dictionaries. Again, I highly recommend that you go back, you check it out, you understand what's happening. These are crucial moments in our journey in data handling using dictionaries. And I will see you in the next one. 111. 10. Adding Items using setdefault: Welcome back, my favorite Python developers. In this video, we'll continue working on our project. This will be the last video related to this project, so we're going to be adding items using the set default. And we'll see what the difference is between the set default and the get that we were using before. Let's go ahead and get started. First of all, I'm going to create a new file in here, a new file, just so we can test out the set default, or first of all, to see what it actually does and how it looks like. I'm going to create the underscore set. Underscore Default. Boom, there we go. Then I will say from computer parts, content. Import computer parts storage. I'm just getting the storage in here. Let me close this down. We don't need it for now. And then I'm going to want to check out the GPU quantity that we have in our computer storage. I'll say GPU underscore quantity quantity, all right, is equal to the computer storage set default and then I will get the P and then I will say also zero and I will want to print out P, two replacement field and GPU quantity. So what did we do in here? We're not going to run or maybe let's just run and see what the output is, first of all, okay, GPU seven. If we look back at the computer, computer parts content, we'll see that GPU right here is indeed seven. All right, perfect. So if we just look at it on the surface level, it just returns whatever the value is for that specified key perfect. There's nothing more to it, at least on the surface level. But if we offer over the set default, let's see what description it gives us. It inserts key with the value of default if key is not in the dictionary. And then it says, returns the value of the key if the key is in the dictionary. Basically what this does is it has an optional effect, if you want to call it that. If the key is in our dictionary, or the dictionary from which we're trying to access the value offset key. If it's already there, we just returned the values. For example in here GPU, we wanted to get the value at the GPU key, we just got the value seven. If let's say the GPU was not in our computer parts content, then the GPU would be added to that dictionary. There we go. One more thing in here is the zero that I provided. So this is the actual value that would be given. For example, let's say GPU did not exist. Then when we use the set default GPU zero, a new item with the key GPU would be added with a value of zero. We specify what value we want added. Let's try this out by adding a battery because we know that we don't have a battery. If you remember, if you look back in here, we don't have the battery. I'm going to say battery underscore one, T is equal to the computer parts storage default and we will add the battery and zero then I'm going to print out the battery two replacement field battery quantity. If I write click and I run, look at that, I get a value for my battery. This looks good. This is something that we are expecting because of the default value that we've said, because of what we explored. But this looks awfully similar to something that we used before, which was the second, let me find where it is. The where did we use the dot? Get somewhere around here. Where is it? Why? There we go. We use get where We would try to get the value from our dictionary, but in case the dictionary did not have that key, we would return a default value. This looks awfully similar, but as I told you, the difference between these two is, wait, I'm not going to tell you. We're going to test it out. We'll add a sound card underscore quantity because we also lack a sound card. And I will say that it's computer parts storage. Do get. Sound card, comma one. And actually let's add two batteries in here. Here I will print out the sound card. Two dots, replacement field sound card quantity. Right click, run. There we go. Now we have two batteries and we have one sound card. But there is a difference between using the get and the set default. Let's see how that is in here. I'm going to print just an empty space. I will print out that storage now contains three dots. We're reprocessing things, we're looking through the storage. I'm going to say four key value in sorted. I want to sort out my computer part storage items. The sorted is just a little bit of extra, it's not super required. In here, I will print out the key value and add a separator which will be just a column right click and run. Let's see what we have. Look at that. We have a battery, but if I scroll down, I cannot find a sound card anywhere. So that's the basics of it. The battery was added, the sound card was not. So the set default actually adds to our dictionary, while the get simply prints out a value in case there's nothing in there. This is a very standard procedure of adding to our dictionary in case we are working with something like a shopping list. Challenge is going to be to update our method. First of all, back in our computer builder script, I don't know why that's a point on its own. You'll need to improve our code by using set default. Simply access the data using the item key and use set default with item and add the amount to it. Pass the video right now and go do the challenge. Okay, how did you get on with that? It's not an easy challenge, but if you take your time, you should be able to do it. Let's go back into our computer builder file. And in the method where we were applying the data or applying to the data the amounts that we were getting, we're going to change it to have it work in a better way. I'm going to comment these out just to keep them for later on. Maybe you want to go back. You want to see what changes we've made, how we improved our code. And I'm going to say that data, that item is going to be equal to data. But said default item that we're getting zero plus amount. What is happening in here? Why is this single line of code, first of all, so complicated? Second of all, why does it alone replace these two lines? The first thing that we should notice is that we are accessing the data, which would be a dictionary at specified item. First of all, we're either adding or are creating a new item in there. Then we are using the set default on the data using the item. What this will do is it will first of all check if that item is already inside our data. If it's inside of our data, if the item key, or we have a key that is also equal to the item, we will get the value from it right here and it will be added to the amount, and then it will be set to the data item. And always good in the world, but in case there's not an item in this data, then we will set it to default, and then we will add the amount to it. And this should fix all of our problems. Let's go ahead and write, Click and run, but before we do wait, I think in here it's a good idea that we print out the computer parts storage. So in here I will get a gaming PC. I, you know what, Let's get the whole package. We will buy all five of these. And now I will hit zero and we should see that Ram 28 battery one touch pad 11111, everything is one. And we've added everything to our dictionary, so the output is the same as we had before. But now, instead of using two conditions, keep in mind this is not something to necessarily look down upon. Avoiding Using a condition in here could help us out a lot. We simply call one function, now it's debatable, which is what's more efficient? What's more elegant? Definitely using this line is more elegant, It looks more professional, more in depth. And it helps avoid certain problems that can arise from using something like this. This is similar to the choice between dot get and the Dos defaults. Default is simply more advanced. It's better could avoid future errors. So thank you so much for watching. We are at the end of our project. I hope you enjoyed if you're still not sure how all of this works, especially this part of the code. I know some of you may be know in general how this code works, but if you want to go through every single line, you might get confused. I highly recommend that you go through this one more time. Make sure that you understand everything properly and leave me a question if you have any, anywhere that you can. Thank you so much for watching. I will see you in the next video where we will be looking at creating, updating and something called values dictionary from sequences. Thanks so much for watching and I will see you in the next video. 112. 11. Creating, Updating and Values Dictionaries from sequences: Welcome back my favorite Python developers to a brand new video. And in this one we're going to be learning about creating, updating, and something called values. Let's go ahead and get started. The first thing I will do is create a new Python file that I'm going to call methods. There we go. Now in here I'm going to create a surprise surprise list computer list which is going to have the CPU GPU. By the way, of course it doesn't matter if you use double quotations or single quotations. I just try to use both of them from time to time. Then we're going to create a new underscore dict which is going to be a new dictionary. And I will say dict dot from keys and then computer items and I will print out the new dictionary. The first, there are two new things in here, the dict and then the from keys. Let's talk first of all about the dict dot. You'll see this is the class dictionary. We can hold control and click on it to go to where this class was defined. You can read all about it if you want. You can even go through the documentations right here. If I hover over this, you can even go to the documentations all about the dictionaries, how they work, what they do, what functions they have, everything that you can think of. You can come in here, look at the copy, look at the items, for example, look at the keys, the pop, there we go. Some of these, we've already seen the set default, the update, we'll see in just a bit the values that we'll see also later on and so on and so forth. A lot of useful information and one of the methods available to our dictionary is the from keys. If we hover over it, what does it say? It creates a new dictionary with keys from itteruble and values set to value. Mm hm. So basically what it's saying is that it will create a dictionary with keys from an itterble. So the itterble could be a list, could be a string, could be a topple, Whatever that itterbal is from, the items in that itterbal will create a dictionary, or the items that were in this itterbal will become the keys in the dictionary that we create. Let's see what happens when we write Click and we run and look at that. So we've created a dictionary out of the keys in our uterble, which is the list in this case. And you'll see that the values are all none. The list items became the keys for different items in the new dictionary that we created. But we could have also specified a value instead of having none, we could say zero. Now when we write Click and look at that, they all have zero. And from here we can start changing things, updating things, and so on and so forth. Let's continue and let's look at updating. I'm just going to have a small print in here and I'm going to say that I have one and it's equal to a, then one, then 2.3 I'll have also two, which is going to be A. Wait four, D five. There we go. Now we have these two dictionaries. You'll notice that only one item has a key in common between them, which is the B. I'm going to say that dice update two, let me tell you what the update is. We'll have or over it and see what it is. But first, we'll have value in dice items and we'll print out key value column. If we hover over the update, it does not provide us with a lot. On the contrary, it provides us with too much for some reason. Let me try to do this again. Yep, still isn't showing properly. Anyways, let's try to right click and run and see what happens. You'll see that we're printing everything from dict one on the items, the key and the value. You'll see A is one, B is. Four, C is three, and D is five. So at this point, with your knowledge of dictionaries, you should be pretty sure what's happening in here. Just like we've seen before. When we try to add another key into our dictionary. The key doesn't get added as a separate item, just updates the previous location of the key, not the location the previous value of the key. For example in here the only thing that's in common is the B. The B goes 2-4 when we update dictionary one with dictionary two, and then this item with a key D gets added to dictionary one. I don't think that's too complicated. I think it makes a lot of sense. Now let's continue on, and let's look at using the enumerate on one of our dictionaries and what happens in that case. I'm going to add another print. Let's continue from here. I'm going to create three, which is going to be equal to the following. We have zero as the key. Notice that it's an integer, and the keys can be integers. It will be a display. Oh my god, come on. One. The keyboard two, touch pad three, SSD for the HDD. All right. There we go. This is dictionary number three. And we're going to have did. We will update it with the enumerate over the computer items. That's a big, big, fancy line there. But in any case, I'm going to copy this and I'm going to print out **** number three. Before we run, I want you to think of what's going to happen here. Please take a moment, think of what the enumerator is going to do. And I know there's a highlight here, but this is not going to cause any problems. Do as Maybe intelligent is just warning us, you know, maybe something bad is going to happen, but I don't think so. I want you to think of what the enumerate usually returns, what it gives us. And then when it's used on the computer items and used to update dictionary three, what the output is going to look like. Take a moment and think about it obviously past the video when I write click and I run, look at what I get. So my dictionary three had at zero road display at one, keyboard at two, touchpad at three SSD and at four HDD. Now after my update here at zero I have CPU, at one I have GPU, and at two I have ran. So what happened in here? Well, what happened is, and by the way, the 3.4 stayed the same. And this should be a huge indication to you, the computer items is the list that we created right here at the top, we have CPU, GPU, and Ram, and they conveniently went into their positions. Why is that? Well, because remember the enumerate returns the index and the value associated with that index. We have zero CPU, one GPU, and two Ram. When we do the enumerate, we get the zero CPU, 12 Ram. And then when we update dictionary three, it just looks at it and it says, okay, so zero was display, but now it's CPU, one was keyboard, but now it's GPU and three or two was Touchpad, and now it's Ram. And then on the SSD and the HDD, nothing changed because we don't have extra elements in here. If we had an extra element right here, it would change the SSD as well. Okay, I hope that was clear. I will try to do something to maybe make it even more clear. What do you think would happen if I changed this 2-6 Think about it. Take your time. Think about what the output would look like if I write click and I run, look at what I get bit weird. Let's diagnose it. First of all, the CPU and the GPU go through the same process. Where we have the computer items 01.201 but there's no two, the 0.1 get replaced. Then we have the touchpad. Correct? Touchpad stays the same. Three SSD stays the same. Four HDD stays the same. Now the question is, how did the Ram get here? Well, remember we still have the Ram. We still enumerated over this entire computer items list, we have 01.2 The only difference is that the 0.1 were replaced using the CPU and GPU, but the Ram was added at the end, at the bottom after everything else. Just in case you're still unsure of what's happening in here, I will just say four value in enumerate over the computer items and then I will print out the index value. And the p will be, as always, these two dots. And let me just add a print in here just so we can separate things. Look at that, CPU GPU, Ram 01.2 they were used to, they were to replace the display and the keyboard. They were not able to update the touchpad, the SSD, nor the HDD, but the Ram was still added at the end. This is how we can update our dictionaries. Before we move on, let's go ahead and look at values in here. I will do another print, I will three underscore values is equal to dict three values. I will print out dict three values. So if I write Click and I run, what do I get? I get dict values, CPU, GPU, Touchpad, SSD, HDD, and Ram. So what is this? Basically it returns a view object that contains the values of the dictionary. You can use this method to iterate over the values of a dictionary or convert the values to a list or maybe another data type. It's very useful to check what the values that are inside of this dictionary are. So look, we have the values that are represented. So we have as the keys, the 016342, and inside we have the values. So now we have this list of values and we're going to see how this could help us. And actually when I say we, I mean you because you have a challenge to check for an. So I want you to use the dot values to iterate over dictionary three, even though I've done this for you already. But I want you to print out all of the values, and I want you to use an F statement to check if we have Ram in our dictionary using the values. Pause the video right now and go to the challenge. Okay, welcome back. How did you get on with that? We've already used the values. I'm not going to delve again into it. What I'll do is, I'll say if Ram, actually Ram in dict values three. I should have. Sorry for this. Okay, what am I doing? Hold down shift shift Alt to move this down. Make our code look good. And it's going to be three values. If Ram is in the **** three values, I will print out, you have Ram, Ram. Congrats. If I write Click and you'll see that you have Ram. There we go, so you have Ram. Congratulations. As you can see, this is a faster way of us going through the values. Because remember, if we do, if Ram in dict three without the values that we're checking right here, it will simply iterate over the keys. Then if we wanted to go through the values, we had to use those keys and put them in a dictionary and then extract the information. A long process, this allows us to access the values directly. If you're still looking at this, this is called a view object. It's something a bit more advanced. I don't want to delve too deep into it right now, but if you're like a way way, what the heck is even object are these real values. You can simply do a four loop, four value in dict values and print out the value. This should become very clear right now that we are iterating over the values. I hope you enjoyed, sorry for the very long video. Honestly, I was not expecting it to be that long. But we learned a lot. We learned about creating using the From keys. We learned about the updating. We learned about enumerating. We learned about updating and enumerating and we values, so a lot of valuable information. In the next video, we're going to be looking at shallow copy and then deep copy and we will be done with dictionaries and move to sets. Thanks so much for watching. I hope you enjoy it and I will see you in the next video. 113. 12. Shallow copy with Dictionary: Welcome back my fellow Python developers. In this video, we're going to be looking at shallow copy and dictionaries. Or with dictionaries, let's go ahead and get started. First of all, we need to understand that there are two types of copying. There's the shallow copy and then there's the deep copy. We'll be looking at deep copy later on. First of all, we'll go to file and create a new Python file which will be the show underscore copy K. Let's close this one down. We don't need it for now. And we'll create dict one which is equal to a one. Oh my God. And close this down again. Let me copy this because honestly, I'm feeling lazy. Base, base this Bc23 space. Does it look nice? Yes, it does. All right, so in here I'm going to say that I have **** two equal to **** one. **** one at position or at key B is equal to 15. Then I will print out **** two At look at that. What I did is I changed the value of the key on **** one. What do you think the output is going to look like? I will write click and I will run, and now I will get 15. Hm. Interesting. Even though I changed it only on dictionary one. Dictionaries are mutable, which means that you can change the content of a dictionary after it has been created. This is very important to keep in mind, but what can we do is actually create a copy of our dictionary without having that second dictionary change, just to keep an old version of our dictionary. Let's go ahead and do just that. I'm going to comment this out, this line out. Instead, I'm going to say that dict two is equal to dict one copy. Then in here we change dict one at B. I'm going to print out **** two. Let's go ahead and also duplicate this and print out dict one at kb. What do you think the output is going to be now? Well, if you don't know what copy is, it just creates a shallow copy of D. If I write click and run, it should be pretty obvious that first of all it didn't work. Now it works. Look at that. On the dictionary number two, we still have B as two. On dictionary number one, we have at 15 because we only updated dict one. When we create a shallow copy, it means it's a completely different copy, a completely separate copy. And we're going to see more examples that explain this. But this should be pretty straightforward. There's nothing too much in here to think about. I'm going to add a print and I'm going to continue on in here. I'm going to create the original underscore dict. I'm going to say that the original dictionary is going to be a two dots. Pop 111 space, copy all of this, and then paste and paste. We're going to have B and C and have 2202333. And we'll just remove this even though it won't cause any errors because Python is that amazing, but better to keep it clean. And then here I'm going to have shallow underscore, underscore dict and it's going to be equal to the original dictionary copy. Then I'm going to say the original dictionary at position at kb. Old habits die hard. Append and I will append by 22. What is happening in here? I want you to really think what the output is going to be like when we print out the original and we print out the shallow. First of all, what does the append do? Please remember the append. Append, okay? Or appending means it adds to it. So remember in here we have dictionaries with keys, strings, and the values are lists. So right here, this is a list. So when we say append, we are adding two to 222 to two, okay? So we're adding 222 to the list on B. This is what we mean when we do this, because when we extract the value at key B, we have a list which means we can append it. So what do you think the output is going to be when we print out the original list and the shallow? Think about it. Boom. There we go. Yeah, wait, wait, wait, wait, what? Wait, Isn't this a shallow copy? It is, isn't it? Then why did the original also change in weird, but very interesting indeed. Let's take a challenge in order to understand what happened. What I want you to do is to create separate lists out of each key value. What I mean by that list should be 111, list B, 222 should be 333. Then in the original dictionary, I want you to set the keys a, B, and C to their corresponding list. Meaning we don't want to literally say that a is 111, is 222, whatever. We want to say that a is list a, B is list B, C is list. And then I want you to append list and I want you to tell me what happens to both dictionaries and how do they behave. Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? I'm going to have a equal to this. Duplicate this twice. We'll list list 2202333. Now instead of this, we'll have list a list list. Then we need to, instead of doing this, I'm going to comment this out. I'm going to get list B append 222. Now if I write click and I run, the output stays the same. But it should be much more obvious how this changes the shallow copy as well. I might have made a mistake. I was saying how did the original copy change? Because we actually changed the original dictionary. What I meant to say, how did the shallow copy change? And as you can see, it's because lists are mutable. In here we got the list, we appended the list. And the list appended not only on the original dictionary, but also on the shallow copy of it. So the list actually updated. The list is an object that we updated, and because it's mutable, it also updated on the shallow copy and everywhere else. So we're updating a list. Okay? That's why the shallow copy had its values also updated. Let's bring this home and make sure that we fully understand it in the original dictionary. I'm going to do the following original at key B, append and I will append added original. The shallow copy added via shallow copy dict. Even though it's a list of integers. We are appending it with strings. When I write click and I run, look at that, I get both. Okay? This is because when we are appending one dictionary at a certain key, it means we are appending that list. And lists are mutable, which means they change across all of our program. So regardless of if we use the shallow or if we use the original dictionary, we are appending a list which is changing. And it will change across all of our dictionaries. If we're using the same list, I hope that makes sense. It might be a little bit confusing, but if you go through the steps and you understand that these were just simply lists, it becomes much more obvious. Thank you so much for watching. In the next video, we are going to be looking at Deep Copy with dictionaries and I will see you soon. 114. 13. Deep copy with Dictionaries: Welcome back my fellow Python developers to a brand new video, and in this one we're going to be looking at deep copy. Let's go ahead and get started. First of all, we're going to create a new Python file that where we are going to be doing our deep copy stuff. Deep copy. Hit enter here. First of all, I'm going to create the original underscore dict. It's going to be equal to the following. We're going to have a two dots, 12. And then we'll have to do, I keep calling them two dots. These are columns. They are called columns, but the name is not as important as the functionality. And as long as you understand what's happening, this is a dictionary, with the keys being strings, being letters. And then we have inside the value, which is a list. Next we're going to create a shallow copy. Shallow copy and shallow copy dict, let's call it. And it will be equal to the original dictionary copy. We've seen this in the previous video and how it works, I'm going to print out the ID of the original dictionary A. Duplicate this and print out the shallow, shallow copy. Dict, shallow copy. Yeah, there we go. So we are printing out the two IDs of a first of all of the original and then of the shallow copy. What I want you to do, what I want you to do is I want you to think of what the IDs are going to be. Now, obviously I don't want you to guess the exact ID. I want you to guess if they're going to be the same or they're going to be different. And it should be obvious if you clearly understood what happened in the previous video. Think about it before you run. And when we run, you'll notice that they are the same. Now why are they the same? Well, this is because it's a shallow copy, if you remember. Because the shallow underscore or shallow underscore copy, underscore dictionary, it's because the shallow underscore copy, underscore dict is a shallow copy dictionary of the original one. What happens is the items or the value inside of the items of the original dictionary, which are lists, stay the same. In here, notice we're copying at a at the key a, which means we are referring to the same list. We've seen the result of having this shallow copy. When we change one list, the other one changes on the second copy. Now we're going to be looking at deep copy and it's going to be a challenge for you to create a deep copy. First of all, look up how to create a deep copy of a dictionary. You can go to a website called Geeks For Geeks, I think it's called. You can check out how deep copy works there. Create a deep copy of the original dictionary, print out the ID at the key a, and try appending the original dictionary so that we can see what would happen in that case. Does the deep copy change when you change the original dictionary? Pause the video right now and go do the challen. Okay, welcome back. I hope you tried your best to go and search on how this is done. It's very important for you to also understand how research works. So first of all, I'm going to import copy. So this is the first thing we need to do. There is a module that we need to import which is the copy. Next, I'm going to create a print in here just to separate things. And maybe even, let's just do a few stars in here multiplied by 50 so that we know that we are now entering into the world of deep copy. We had shallow copy, now we're working on deep copy in here. I'm going to say underscore copy. Underscore dict is equal to copy deep copy of the original dictionary. I will print out, let me just copy these because I'm lazy. There we go. So what do you think the output is going to be now? Now, I, obviously you've done this probably at this point, you know. But let's say you haven't done it, you were lazy. Now is the time to stop being lazy. So tell me what these are going to be. Are they going to be the same or are they going to change? When I write, click and I run, you'll see that they are indeed different. Why is that? Well, first of all because at the first time they were the same. So obviously some of the changes that we made should change how these behave. But that's beside the point. This is psychology, but we're talking about real science or programming science. I don't know what you want to call it. You can see that they indeed do change. Because when you create this deep copy, let me hover over to see deep copy operation. Okay? Doesn't necessarily describe this, but if you go and search for it, it actually creates a completely separate items from the original list, from the original dictionary. Meaning that the lists are new, they are completely different, they have been deeply copied, if you want to call it that, to double check this, let's go ahead and try to change the original dictionary. Just like the challenge told us, the original dictionary at a append with 12. Let's append it with 12 and we'll print out the original dictionary. And we will print out the deep copy dictionary. And we will print out the shallow copy. I want you to tell me what the values are going to be before we run the program. It should be fairly obvious that now you'll see that the original one modified, the deep copy was not modified and the shallow copy indeed modified. So there are no changes to the deep copy because these are two completely different lists. They are no longer linked in any shape or form by anything. They have different IDs, they have different complexities. They work on completely different playing field. So I hope this was obvious, I hope you understood what is happening in here. When you're doing a shallow copy, it's a simple transform of the list. But when you're working with a deep copy, you have a completely different dictionary, with completely different lists, with completely different values, and items, and keys. They are not the same at all. So thanks so much for watching. I believe this is the last video on dictionaries. Maybe I'll add more later on, but for now, this is the end. In the next video, we're going to be taking an introduction into sets, which is very exciting. I'm always excited to start something new. Thanks so much for watching. I will see you in the next video. Bye bye for now. 115. 14. Introduction to sets: Welcome back my favorite Python developers to a brand new video. And in this one we are going to be looking into sets. I'm going to keep dictionaries and sets in the same section because they are, well, very similar. I think maybe I'll separate them. Who knows? Let's go ahead and get started. First of all, what the heck are even sets? A set is a collection of unique elements in Python, emphasis on the word unique, denoted by curly brackets or the set function. So this might come as a surprise, but dictionaries and sets are denoted both using curly brackets. But you'll see that it's pretty obvious, or there's a very easy way of distinguishing between these two. First of all, let's look at sets are mutable and can be modified using various methods. They are mutable, they can be modified. Sets can contain elements of any data types. You can have strings, integers, lists, maybe dictionaries, maybe a set of sets. Even you can do that. Sets do not allow duplicate elements. This is very important. Unlike dictionaries where you might have the same key and then you'd have changes to the value. When we're working with, with sets, there is no way that you can have duplicate elements. You cannot have two elements being the same in a set. Sets are ordered. This is very new to us. This is a new concept, meaning that their elements do not have specific positions or indexes. If you remember when we were working with lists, we start at 0123. We can access these elements using their index. When we're working with topples, the same holds true. We can use the index to access certain elements in the topple. And when we're working with dictionaries, we can also access elements using their ID, using their keys. But now, when working with a set, you cannot access any element by its index because they don't even have an index. They are not ordered, they are unordered. They do not have a specific position. And you'll see every single time we run the program, the set is going to look different. Sets can be used for operations such as union, intersection difference, and symmetric difference using operators or methods. We will see all of these in the upcoming videos. So strap on your thinking caps because we're going for a ride looking into sets. They are not very complicated. Sets are actually very simple. Everything that we do is going to be very easy. It's much easier than dictionaries. But keep in mind that it needs concentration. It needs understanding. So this is a set of animals, cats, dogs, horses, birds, chicken, and reptiles. So I want you to tell me if this set or in this set, what's index number zero? You can't because they are unordered. You can start from the top and you can say, oh, dog is slightly higher than cat, Dog is at zero, Cat is at one. But somebody might argue, we want to start from the left, Dragon is at zero, cat is at one, bird is at three. You see what I mean? Every single time it will be different, they are under this, for example, will be a representation in code of what this set would look like. We have a set of animals, cat, dragon, chicken, snake, reptile, et cetera, et cetera, whatever you want to fit inside of this. All right, so enough theory. Let's go and explore using code. I'm going to create a new Python file in here that I'm going to call the introduction to sets or set int int. I will write click and I will close other tabs, we can write Click in here and close other tabs so that we have a fresh tab. Just for the sets in here, I'm going to create fruits and it's going to be equal to apple banana, come on orange, kiwi and pineapple. And then I'm going to print out the fruits when I write click and I run, this is the output banana. Orange apple Kiwi. Pineapple. Mm hmm. Interesting. Did you notice that banana is in the first position and apple is in the third, and then orange is in the second, whilst in our original fruits, apple banana, then orange. You can see that there is no longer an order to these if I right click and run again. Now apple is in the beginning, but there's not a banana after it, there's an orange and the kiwi is at the end. As you can see, they are unordered. Every single time you run the display changes and it might be different on your side, it doesn't matter. You can also iterate over a set. For example, in here I can say four fruit in fruits. Print out the fruit. When you write click and you run, boom, there we go. Orange, pineapple, apple kiwi, and banana. You can iterate over it. If I run it again, you'll see that the order changes. And notice how it's the same as the set that we created, or output it right here. Apple, kiwi, orange, banana, pineapple. This should be obvious. Nothing too much near. There are a few things to keep in mind when having an unordered list. It means that there is no point of trying to access an element from a set, for example. What I mean is if I try to print in here, and I try to print out fruits at position one. I mean fruit, fruit at position one. Notice that we immediately have a highlight. If we hover over the highlight, what does it say? Class set not defined, Get item operator cannot be used on this instance. If I try to write click and run, you'll see that I get an error and actually a type error because the set object is not subscript, you cannot subscribe to it. Unlike my future Youtube channel or the one that is already up, you cannot use the brackets to access certain elements because there's no point. What is at element one, We don't know. There's no order to this. It's not like this order right here. Don't get full. Don't think that one should be banana. Because if I write Click and I run, it's different, now it's orange. There's no point of trying to access. What can we do with sets? Well, we can get two unordered sets and compare them, for example, I'm going to comment this one out. I'm going to create more underscore fruits in here. I'm going to have orange. I'm going to have banana. I'm going to have apple. I'm going to have pineapple and kiwi. There we go, You'll notice that it's the same, but these have two different orders. Interesting, at least when we rolled them. I'm going to say fruits is equal to more fruits. I will point out they are the same else. I'm going to say they are not the same. What? They are not the same. What do you think the output is going to be? Are they going to be the same or are they going to be different? Think about it. Tell me what you think. When I write, click and run, boom, they are indeed the same even though their order is different. Because there's no point to having an order. They have the same elements inside of them, which means that they are indeed the same. If I change this and for example, add cherry here. Now if we write Click and we run, you'll see that they are not the same. They can be used for comparing. Let's continue on and let's look at something that I might have not talked about as much as I should. You'll see that in here we have something where we said denoted by the curly brackets or by the set function. Let's look at the set function and how it operates in here. I'm going to add another print. I'm going to say numbers, numbers underscore list is equal to 12,318.9 Then I'm going to print out the set of numbers list. Before we run, let's look at the set I have right here, new empty set object built an unordered collection of unique items. If I write click and I run, there we go. You can see that we've created a set of these numbers that we have noticed that they are unordered. Even though 12.3 they are ordered in, if you want to call it like their order of the integer meaning 123918. Maybe if we add like five in here, it should also go in the correct position. There we go. But this is just by default. It's not because the set gets ordered, you cannot access elements inside of it. So I hope you understood this is not too complicated. Sets are fairly easy. Now I have a challenge for you. Your challenge is going to be to set a string, create a string variable, any string variable you want, convert it into a set using the set method, and print out the output and tell me how it looks like. Okay, so pause the video right now and go do the challenge. Welcome back. So how did you get on with that? Shouldn't be too complicated. Simply in here, I'm going to print out just an empty line. And I will say string underscore var is equal to Hello World. And I'm going to print out the set of string before we run. If you haven't done the challenge, even though I'd be very disappointed if you haven't, We need to right click and run and you'll see that this is the output that we get. We have the space, obviously, because it's also a character, the W exclamation mark, et cetera, et cetera. Because remember also something very important in here that you might have overlooked. How many L's do we have? We have three L's in our string var. How many L's do we have in our set? Only one. Why is that? Because inside of a set, you cannot have duplicate elements. I hope you understood. Thank you so much for watching. Keep in mind that because this is an interbal meaning that each character is an item in the string, just like we have a list in here, that's why we have each character being an item in our set. Thanks so much for watching. I hope you enjoy it. In the next video, we're going to be looking at adding into sets and duplicates. So I will see you then. 116. 15. Adding in Sets and duplicates: Welcome back my fellow Python developers. In this video, we're going to be looking at adding items to a set and checking duplicates, meaning removing duplicates from a set. Let's go ahead and get started. First of all, I'm going to create a new Python file in here that I'm going to call adding underscore two underscore sets here I'm going to create numbers, so I will initialize numbers, but the problem is, is this a set or is this a dictionary? Mm hmm. Let's not try to imagine this. Let's just try to actually test it out. Let's check what type number is. If I write click Run, you'll see that the class is that of a dictionary. Well that's because in order to initialize a set, we need to set it as this function. Now when I write click run, you'll see that I indeed get a set. So how do we add to the set? Well, I'm going to go ahead and do the following, saying that number ad, and I'll just add 42, the answer to the universe. And I will also print out numbers, right click, Run. And there you go. You can see that I have 42 inside of numbers. Add simply adds nothing too much in here. Let's create a loop that keeps adding to our set. In here, I'm going to add a print, and then I'm going to say, while the length of numbers is less than six, I'm going to create the value underscore two. Underscore ad is going to be integer input and inside I'm going to say, please enter the value to add the value add. Let me make this bigger. In here, I'm going to say numbers, value. Then I will print out numbers at the end. Right click and run. We're going to be getting inputs. I don't think this code needs to be explained too much at this point. You know exactly how we loops work, you know exactly what length is, you know exactly how to get into your inputs. Now we just learn how to add. I don't think there's too much in here. Let's go 1216, 4089, 0230, 2605 pumps. I was looking at my keyboard, as you can see we have these different numbers. All of them have been added and they are set. And notice that they don't have the same order as we've added them when we were doing input. That is very good and it's an indication of how class or how our sets operate. Let's now try this again, but this time I'm going to add 122 times. There we go. You can see that now we have a 12 in here. And by the way, if you're counting the numbers and there are still six, keep in mind that we added 42 right here at the top. Keep that in mind. You can see right here that we have 42. I 12 only added once even though we've added it multiple times or tried to add it multiple times. Let's add 12 times. There we go, Look at that. If I keep adding 12 even before we do this, it will keep trying to get inputs because the length of numbers will never go above six. Because we keep trying to add 12 and the duplicate is being removed. So this is one good functionality of having sets in case you ever do or don't want to have duplicates in your code or in your lists or sets, or any data set that you have. You can shove it into a set, it will just remove the duplicates. So it's a great, great tool. Let's continue on, and let's now look at removing duplicates in various ways. I'm going to create a new Python file that I'm going to call removing underscore. I'm going to have a list of orders. Will one come up? And a few times I will order 234567. I think that's enough, but I want to scramble them. What I mean by that is I want to 132. Let's just keep 45 to 83123456. And let's just have a seven here and a five here. Okay, so as you can see, there's an issue in here. The issue is that we have order two appearing twice, correct? Yeah, only twice. So this is an issue and maybe the user or the programmer did not notice this or there was a bug in the program to get it order unintended. In order to make sure that we don't have duplicates inside of our orders, we can convert this into a set. And when I say we, you know the drill, I mean you, because you need to create a set, you'll need to create a set out of the lists of orders that we can have. Use the set function and print out the result. Pause the video right now and go to the challenge. Okay, welcome back. How did you get on with that? I'm going to have the unique orders, and it's going to be equal to a set of orders, and that's it. And now when I tried to print out the unique orders, you'll see that they are all different and we do not have duplicates. How cool is that? Now, of course, you could have went through this list and tried to check if you have order two multiple times. But what if you had order seven appearing three times, order 25 times, order 310 times? It would take a lot of time to make sure that there are no duplicates, a lot of statements, a few four loops, a few y loops. Using this, you can simply shove your list that has duplicates into the set function, and it just returns a new set with no duplicates. It saves us a lot of time. We could also do the following. Instead of just having these orders, we could have them sorted instead of these being random and all over the place. If I write click on There we go, you can see that they actually get sorted. And notice something very important as well. When you use the sorted, it converts it into a new list. Now you have a sorted list of your orders as well, without any duplicates. But what if you wanted to keep the same order? We can do the following. Instead of using the sorted, we can say that we want to have, actually let me duplicate this. Let me take this back to its original form and then comment it out. And duplicate this as well. And comment it out now, so that you can see all the phases of our project or program or example. We can do the following. We can say dict that from keys, orders. Now when I write click and I run, look at what I get, I get order 13247865. Okay. That's too long. Okay. Let me put it down here. Or actually, I could have used the bar. Why didn't I use the bar? You'll see that order two only appears once and order three is in the correct position. Using dictionary, what you could do is let me duplicate this, turn it into a list. There we go. Now you have a list which still has the same order of orders. The set, unfortunately, will not preserve the order for you. This is an overview of how you can add, how you can convert, how you can create sets, and we are beginning to see how useful this can be. In the next video, we're going to be looking at erasing items from sets. So I'm very excited to see you there. Thank you so much for watching And I will see you in the next video in a few seconds maybe. 117. 16. Erasing items from a Set: Welcome back my favorite Python programmers to a brand new video. And in this one we'll be looking at raising and deleting, and discarding and clearing everything that involves taking elements or items out of a set. Let's go ahead and get started. First of all, we're going to create a new Python file that I'm going to call decrees set here. I'm going to create the computer underscore components and it's going to be equal to the following set. We're going to have a CPU, GPU, Ram control, SSD control D, and HDD. A few computer components. Let me put this back on the right hand side to have more space. Let's first look at what happens if we want to clear out the entire list. I'm going to simply get computer components clear and then we'll print out computer components. And if we write, click and we run, this is what we get a set. Notice that we don't have two curly brackets with nothing inside of them because that can be confused with an empty dictionary. It's a set with nothing inside of it. Let's continue on and let's look at two different ways of removing items from a set. I'm going to comment these lines out in here. I'm going to say, computer components. Remove the SSD. Duplicate this, and now we discard them because we've, the SSD should be removed. Also, we want to print this out. Let's move this one up right here. If I write click and I run, I should see that the B and the SSD were both discarded. If I write click and run again, there we go. You can see that they are no longer there. Very nice. Why do we have two ways to remove elements from a set? Why not just have one? Since both of them work well, this is going to be a challenge for you to raise something that is not in our set or not there. Try discarding an item that is not in our set now. Or try the mouse, for example, print out the components. Now, try removing the mouse, what is the difference? Pause the video right now and go do each challenge. Okay, welcome back. I hope you tried your best to. Let's comment this out as well. In here, I'm going to do a print. We don't need a print in here. I'm going to simply print out, oh my god, this, the mouse, three dots, computer, mouse, and print out computer components. Then, let me just copy these two lines, because I am lazy in here. We're going to remove and remove, mouse and print out the components. And let's see what happens if I write click and I run. Boom, There we go. You'll notice that if you try to discard something that's not there, there is no error raised. But the remove does raise an error. It depends on the situation that you're in. You would use either the discard or remove. Maybe you're saying to yourself, well, why not use the discard all the time? Since who has time for errors or another question you might be asking, shouldn't we always be getting an error? Because we need to be careful about what we're removing? So again, it depends on the situation. If the information that you're trying to remove is not sensitive, you don't care if it's there or not. You just want to try and remove it. You can use the discard. If you're very worried about what you're removing, you want to make sure that you're removing something precise, correct. You can use the remove method instead. It depends on the situation. And if we hover over, these methods removes an element set number. If the element is not there is not a member, do nothing. If you hover over the remove, you'll see if the element is not a member, raise a key. Or finally, we have the last method for removing items from a set, which is going to be the pup. We've already seen the pop, but let's see what it actually does. I will comment everything out in here. I'm going to go ahead and pop something out. Computer components pop and just print out computer components. How about that? If we don't put anything into the pop, what happens is a random element or a random item gets removed. This is useful in situations like random removal. Maybe you're looking to increase memory efficiency because using the discord and you remove can create new sets. Sometimes sets are mutables, sometimes sets are mutable. When you're discarding and you're removing, you're creating new sets, it's less efficient using the pop. If you're not worried about which element you're removing, you just want to remove an element. Random removal a game maybe or something. Then set is your best friend. Thanks so much for watching. This was a very simple exercise. In the next video, we're going to be looking at union, which will help us understand better why sets are useful. Thanks so much for watching and I will see you in the next video. 118. 17. Set union: Welcome back my fellow Python programmers to a brand new video. And this one will be looking at set union. So let's first of all understand what it actually is. Let's say we have set one which has 123.6 and we want to create a union between set 1.2 which has 754.8 the resulting union, and this is how we would write it, this is the operator in Python that we use to create a union. The result would be a third set which has 123 both set one and set two together, all meshed up. So let's see a practical application of this. This was a small sneak peak in two challenges, but not the full peak. You'll have that in just a bit. Let's go ahead and create a new Python file in here. And let's call it the underscore e mail. Yes, because what we are trying to do in here is we're going to have two sets. The first set set is going to be all the customers that purchased some kind of electronic from a store. The second set is going to be all the people that purchased from the store. What we'll do is we want to check all the people that made a purchase and send them a promotional E mail. We're going to first of all, create the electronics underscore purchased and it's going to be equal to John. This is not how you write John. This is how you write John, Sarah, Peter, and Anna. Duplicate this. We will have the clothing purchased purchased. Yes. We're going to have John, Emily, William, and Anna. These are the people that bought electronics. These are the people that bought clothing. Now we're going to say all underscore customers equal to electronics purchased, union clothing purchased. And now we can print all customers. If I write Click and I run, let me put this down here. You can see that we've created a union. But even better than that, we don't have to send John and Anna two e mails. Because when we create a union, we're creating a third set. Meaning that all the duplicates are removed automatically. How cool is that? It saves you a lot of time, a lot of headache. You already know, because in this situation, you don't care the order. You don't care if you send Sarah or Peter, or John or William, whoever it is. You don't care who receives the e mail first. All you care about is that everyone that bought from your store receives an e mail. So that is perfect. In our case, we've created this, and now we can send them an e mail to all the customers. But there is a different way of creating a union. We can use the operator that we just saw. So I'm going to duplicate this line actually. And I will have all the customers. But this time I'm going to add this pipeline character. Yes, this is called the pipeline character. Each keyboard has it in a different position. On my side, it's above the entarkuy, there's the backslash, and then there's the pipeline. If you hold down shift and click it on a Mac, I have no idea where it is. You have to do your best to find it. But this is the pipeline character. And if you right click and you run, you'll see that we also unionize. Unionize that, that's that's for something completely different. We create a union between the electronics purchased and the clothing purchased. I hope you understood the assignment. I hope it wasn't too hard for you. There's nothing too much in here. Very simple union between two things. Now I'm going to issue you a bit of a challenge, and your challenge is going to be to print out sorted. So all you need to do is print out all the customers in a sorted list. Hm, interesting sorted list. Keep that in mind. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? Shouldn't be too hard. We've already seen this before. This is not what I want in here. We are going to, instead of printing out all the customers directly, all that we need to do is we need to say all customers. That's actually, not only will this sort out the people that are there, it will also create a list out of it. There we go. Now we have a sorted list by name just in case you needed it. There is also a way to add the two sets together using the update. If you remember, if I do the following, I do, electronics purchase, update closed, I print out the electronics purchased. You'll see that I also have this and there are no duplicates is the same as the one that we've done before. What is the difference in here? By the way, the update also has an operator of its own. I will duplicate this and I will comment this one out. You can do the following. You can say electronic purchased and then you can Pipeline equals clothing purchased. This does the same thing. All right. Click Run. Look at that, The pipeline, you don't have to remember the operators. And we'll talk about the difference between using an operator or a function, But the main difference between the union and the update is that the union returns a new set containing all the elements from both sets, while the update modifies the original one, the one that we're using on the left, for example, the electronics purchased by adding all the elements from the other set. That's the only difference. Before we move on, there is one more thing worth talking about, and that is when to use a function name and when to use the operator. There are three main things that we need to think about in here. First of all, it's clarity, flexibility, and error handling. If we look at clarity, using the set operation methods like union and intersection, which you'll see in the next video, can make the code clearer and easier to read, especially for people who are not familiar with such operators. First of all, if you're looking for clarity, using methods is better. Now, when it comes to flexibility, the set operation methods are more flexible than the operators as they can be used with a variable number of sets. If you want to pass multiple sets to the argument union, maybe you want to create multiple intersections. Maybe you have ten sets instead of just one or two, whereas the operators can only work sets at a time. And finally, when it comes to error handling, methods are also better. The question becomes, why use an operator? There's no real reason, like it depends. Sometimes if you have some quick stuff you want to do, you want to accomplish these two sets like quickly. You know you're doing mathematics, You don't want to have too many functions, maybe it depends also on the situation. If there's nothing too complicated, using an operator is perfectly fine. I think the operator might use slightly less computational power. I'm not 100% sure about that, but I do think that is one advantage of using operators. It's slightly faster in the millisecond realm. For example, if you're using it in a loop and you only have minimal error, error handling requirements, using an operator would probably be a better choice here. But in any case, if you're ever in doubt, use a method like the dot union and not the operator. Thanks so much for watching. I hope you enjoyed. In the next video, we'll be looking at set intersections, and I will see you there. Bye bye for now. 119. 18. Set intersection: Welcome back my fellow Python developers to a brand new video. And in this one we're going to be looking at set intersection. So first of all, let's look at what set intersection is in the first place. This is the operator for the intersection. We have set three equal to set one and set two. Unlike like the union, we create a third set. So if we have set one and set two, set one has 625,738.4 Set two has 5 731-323-1917 The intersection would be this set right here. The set three in this case would be 57.3 Let's go into our code and let's actually try to apply this intersection and see how it works. Back in here, I'm going to create a new Python file that I'm going to call intersection underscore set, hit Enter, and I'm going to create set one. Which will be equal to set range. And the range is going to be 050.2 Duplicate this. We're going to have set two. And this time the step is going to be three. Remember ranges where you have the starting point, the endpoint, and the step. Let me print out set one and set two. When I write click and I run, look at that, I have 0, 246-810-1214, et cetera, Two steps at a time. Now the second one is scrambled. I don't know why the first one is not. I'm not entirely sure. Let's try to run it again again. Okay. Apparently we're getting the same. I think sometimes it just selects random numbers, sometimes it doesn't. I'm not entirely sure. Oh, wait. We do have a few scramble numbers here, like 40, 42. No scramble number in the first one. The second one has a lot of scrambled numbers, but it's not a problem for us. We have two sets. We want to see where are the intersections in here very easily, we create the in section underscore set which is going to be equal set one, intersection set two. And I can print out intersection set when I right click maybe. Let's add a print in here just for clarity. Right click, run and look at that number. 0306 6402, 1248, 1820. 4.30 are intersections between these two sets in here. So pretty simple, pretty self explanatory. There's nothing too much to do in here. It just finds where there are intersections and it creates a set out of that intersection or out of the items that intersect between two sets. Now let's look at a more useful example in the real world. Let's say we have two lists of customers who have made a purchase at a store. One list would be from January, the other one would be from February. And we want to see where that intersection, where are the people that bought in January and February, because we want to give them a promotional discount or something like that. So I'll add print and I will have Jan underscore customers equal to Let's set. John, can I get the ones that were here? I'm going to use different names. John, Sarah, Sarah. That's all. You're right, Sarah, Emily, David, Katie. Duplicate January, February customers. So, I will have Sarah here, David, Katie, Stephen, and Jenny. Now we want to find the intersection. And when I say we, of course I mean you because it's a challenge to find the intersection. Get the common customers between January and February. Use the function intersection. Use the operator as well that I showed you. This is the operator. And then print out the result of both posit video right now and go do the challenge. Welcome back. How did you get on with that? I'm going to call this the customers and I'm going to say that it's equal to January customers intersection February customers and print out the common customers or the incommon customers or whatever. Right click run, Katie, David, and Sara or all three of these. But in January and February, we send them a promotional. The other way of doing this, I'm going to duplicate this. Come in the line at the top and say the following. Boom. This is the operator that we can use. If I right click and I run, we have the same output, Sarah, David, and Katie. That's basically it. This is intersection. Before we move on, I want to take this opportunity to look at how or how you can create intersections between more than just two sets In here, I'm going to create the march customers. So the march customers are equal to John A, Alex A, Emma, Sarah A. Let's continue using single quotation mark and Katie. Now if we want to create the intersection between three, we would use the following March customers. When I write Click and I run, there we go. We only have a bought in January, February. And as you can see, John did not buy in February in Katie, our loyal customer. So we will give her a special bonus, the other way of using this, instead of having the operator, we can use the intersection. And we do that by simply adding a comma in here and adding this, and we should have the same answer. So ladies and gentlemen, I hope you enjoyed this was set intersection. In the next video, we're going to be looking at the set difference. And finally, we'll look at subsets and supersets and be done with the section. Congratulations on making it this far. If you have leave me a review or a comment or just tell me like, hey, nice, I love this. Of course, thank you so much and thank you for watching so far. I really appreciate it. And I will see you in the next video. Bye bye for now. 120. 19. Set difference: Welcome back my fellow Python programmers to a brand new video. And in this one, we're going to be looking at set difference. Set difference is very simple. We have set number one, we have set number two, set number three, and set number four. Set number four, for example, would be set number two. This entire yellow thing minus the green part. What we get is this part right here without this intersection. In the middle, we will have set four without the intersection. And set three, which would be set one minus set two would be the green part. So these are the set three and set four, this is the difference and the operator is just the minus sign. Very simple. Let's go and look at some practical examples of this back in our code. I'm going to go ahead and create a new Python file, which is going to be the difference underscore sets, and in here I'm going to just copy set 1.2 from here. Paste them in here and we should get a very normal answer just like we had before. It's same range that we're converting into a set. Now we're going to create the difference underscore set, which will be equal to set one difference set two, and then print out the different set. When I write click maybe, let's just add a print in here. Write click Run, and this is what we get. This is the difference between these two. For example, 28 is in the first set, but it's not anywhere in the second set. This is the difference between it. But keep in mind we're doing set one difference, set two. If we change these around, let me copy this and paste it in here. And if we do set two different set one, now we have a different answer. Because we look at set two and remove from it everything that was in common in set one. For example, 27 is only right here in set two. What else? For example, nine is only here if we take a number like 42. It's in set two. And in set one we remove the difference. Doing it the other way around is different. Mm hmm. So let's look at a practical application. As always, let's say we have customers shopping list that includes apples, bananas, and oranges. And we're going to check if we have some kind of promotional items, maybe there's a promotion on these apples or these oranges or whatever. So we're going to create two lists in here. Two shopping lists, I mean, not like actual lists, these are going to be sets. So first of all, we'll have a print and then I will do the shopping underscore list, which is going to be equal to apple, bananas, oranges. And the promotion underscore items is going to be apples and bananas. Now there is a challenge for you, and your challenge will be to find the difference, create the difference between the shopping and the promotion, and use the methods and the operator. Posit the video right now and go do the challenge. The goal here is to get the items that are not being promoted. Underscore on promotion is equal to the shopping list minus the promotion items. So a little bit of challenge here was that you needed to figure out whether to do shopping list minus promotion or promotion minus shopping list. But I think it's pretty obvious. So I'm going to have items not on promotion, Come on. Not on promotion, right click, run. And there we go for a second there. I was stunned. I was like, whoa, wait, wait, what happened? And it turns out that we have apples, apple, right click, and run, And now it should work. Oranges are in the promotion. I was like, wait, wait, what happened? I was stunned because this is so easy and simple, and I made a mistake. I'm like, What happened? Anyways, there you go. As you can see, this is how the difference works. Thanks so much for watching. I hope you enjoyed. I believe this is the end of the section, but we might add more videos down the line. Maybe we'll work on subsets and symmetrical differences, But for now, I hope you enjoyed and I will see you in the next section, which should be reading and writing again. Maybe we're updating. I don't know what we have next. I'm so excited to get started for the next section and I will see you that. Bye bye for now. 121. Section 9 - Reading and Writing Files | 1. Opening Text files : Welcome back my fellow Python programmers to a brand new video. In this video, we're going to be starting a new section which is reading and writing files in Python. This is a very important section. It's very crucial that you know how to write and how to read from a file. Let's go ahead and get started. First of all, what is a text file in a Python context? Obviously, we know already a text file is, but we want to know what is it in the Python context. So first of all, a text file is a file that contains ASC II or Unicode characters. This is a standard in, in which the computer writes certain characters like ABCD, et cetera, et cetera, which can be read and written using Pythons built in functions. We can read and write these files using Pythons built in functions, and we are going to see what these are. They are used to store textual data such as strings, numbers, or any other kind of data that can be represented as a text. Python provides several built in functions to read and write text files, such as open read, write, and close. And we're going to see all of those and more. When working with text files, text files can be opened in different modes, such as read mode for R and write mode. We're going to see these when you want to read, you use, when you want to write. The mode is specified as the second argument to the open function. And we'll see how that looks like when we have the file object is equal to open the text file that we want to open. Keep in mind it's dot, this video will be about opening text files and then we will move on to reading. Stripping, parsing extra, et cetera, using the R right here to indicate that we are reading. If you don't provide it with anything, by default it will think you are actually reading from the file without any further ado. Let's go ahead and actually start applying this knowledge from here. I'm going to go ahead and create a new Python file. New Python file, and I'm going to call it underscore text. Underscore file. First of all, I'm going to create Python underscore poem, and it's going to be equal to open. And we are going to open a Python poem. Immediately you see that we have all of these suggestions. When you have them, just click. Don't worry about it. Now I'm going to provide you with these files somewhere in a button or something. So make sure to download them, unpack them, and then simply drag the Python poem into the reading and writing files right here, it will ask you where you want to do this. Move to D one. For some reason it's like, but if you want to do it in a better way, right click open with Go to Explore in here. Open up the reading and writing files and just send in this file. This is a much better way. Close this down again. Right click open, Explore. Go into the file and send in the Python poem. Down from here, I'm going to say Python poem, and it should recognize it. Obviously, we're trying to read from this file. So we will add an R here and we'll add an extra space. Now that we have this, let's write Click and run just to make sure that we don't get any errors. The open function is used to open a text file and it returns a file object that can be used to read and write data to that file. Now that we have access to all the lines in the text, we need to print out these lines. Conventionally, we call them lines in a text. In here, I'm going to create a four loop because we can iterate over the file object. I'm going to say four line in Python poem. In here, I will print out the line. If I write, Click and I run, this is what I get. Look at this in lines of code and syntax. Clear Python beacons with promised deer with power to transform and create a language to master, to elevate. Now, super cheesy I know. But it's a good poem if you go through it. If you read it, it's not a bad poem. I do recommend that you read through it, but as you can see, we were able to read through this file. Let's open the file and look and see how it actually looks like. If I double click, it opens up an Intellij. Intellij allows us to read, and as you can see, this is our poem. Now immediately you'll notice a few things in here. First of all, we have these extra spaces in between lines. And we also have three spaces in between each paragraph. Obviously, something is going on in here. We're having to get extra lines of code. Now this space is being printed out in the output only. This is because in the actual text document, we have something which we refer to as the Enter. So every single time you finish the line, you hit Enter, you go to a new line, and that key is being printed out in the output. Because remember when we are working with characters, the spaces are also characters, and in this case, the new lines are also characters. So that's why we have these extra spaces. We are reading every single character, and one of those characters is the enter that the user pressed when he wanted to go to a new line. So that's why we get this in the output. Now to mitigate this problem, it's very simple. We simply go in here to the line equals and just do this, meaning that the ending of the line should be nothing. Now when I write, click and run, there we go. You can see that the output is much better and there are no space or no blank lines in there. Keep in mind the white lines which are the space and the tab, and the new lines are all counted as characters. We've already seen this before when we were indexing strings. So none of this should be very new to you. It's just a new way of seeing those things. So now that you have all of this information, time for a bit of a challenge. And your challenge is going to be to strip the unnecessary objects. I want you to look up the method strip on three schools or Google or whatever, your favorite choice of information, Python resources, whatever, use it on the lines extracted from the Python poem. So try to use it on the lines that we are using or we are getting from the Python poem. Print out the strip lines and tell me how it looks. Post the video right now and go do the challenge. Welcome back. How did you get on with that? In here I will comment this line out. I'm going to say that the strip underscore line is equal to line strip and then I will print out strip line. Now if I write Click and I run, this is what I get. You'll see I can now do this without the end. Because what strip does if we hover over, it will give us anything. Returns a copy of the string with leading and trailing white spaces removed. If character is given and is not none, we remove the character that we want instead. For example, if I want to remove the right click and run, you'll see that the white spaces are not removed, neither is the comma. But we will delve deeper into how this works exactly. But for now, don't worry about it. Just know that when we don't provide anything, it actually just strips out the white spaces. Before we move on, there is one more thing that we need to look at when using Python poems or opening up text files, or any files for that matter, it's very important that we always close our files. What I mean by that is once we're finished with reading with writing from a file, we need to always type in the following Python file, close. This is very important because it avoids data loss sometimes if you don't close the file properly. So you know, when you're shutting down your computer and the windows tells you like wait, there are still some files that are open and haven't been saved and whatever. Like, it's a huge deal. Well, it is a huge deal because it can corrupt the data that is inside of a text file. Now obviously in here, it's not a problem, it's just a silly Python poem. But still, we need to close the file, but sometimes it's a bit cumbersome, having to open the file and then close the file and whatever. Thankfully, there is a small trick in here in Python that you can do in order to avoid forgetting doing those things. I'm going to comment these out, please don't delete them, keep them with you. And I'm going to show you with open and then we will open the Python poem or for reading as Python underscore poem. Then in here we'll say four line in Python poem stripped. Actually, why am I going through all of this trouble when I can copy paste this? Here, there we go. So this is a better way of opening the file because it avoids forgetting the close with the width. You actually automatically close the files. Now f right click and I run, you'll see that we get the same output. Thanks so much for watching. I hope you enjoyed this video. This is a new start. This is a new section, so I need your full concentration. It might seem a bit scary at first, but trust me, reading and writing files is not as complicated as one might think once you get used to it. I will see you in the next video, where we will be looking at reading files in. So see you then. 122. 2. Reading Text Files: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at more ways of reading text files. Let's go ahead and get started. First of all, I'm going to create a new Python file in here, which is going to be the reading text files. Reading underscore. Underscore files. Boom. I'm going to close the projects down. I just wanted for you to see the Python poem text in our file collection. For now, I will just close down from here. I'm going to do the following, I say with open Python poem R as Python underscore poem. If it wasn't clear from the beginning. Right here, when we say S Python poem, it means we're creating the file object just like we did in here. But this time it's a little bit different using the width from here. Python poem. I'm going to say that lines are equal to Python poem, red lines. There we go. This is a different way of reading. Then outside the width, I'm going to print out lines. I also want to print out the type of lines. And maybe we can do this just above it. Now when I write click and I run, this is what I get a class of list. And you'll see right here. Unfortunately, I have to move from left to from left to right. But as you can see, each line now has become a part or an item inside of a list, the read lines. If I hover over it, what does it say? Let's open this right here and let's look at read lines, three schools to get an explanation because the documentation just doesn't provide us with anything. It simply returns all the lines in the file as a list where each line is an item in the list object. And it's pretty obvious from the way that we have seen it in our code right here, that we have each line as a separate object. But you'll also notice that some weird characters are included, like the new line that you see in here. Now we're justified in what was happening in the previous video where we had separate lines between each line and the poem. It's because of this character right here, it manifested in a new line in the output. So this is a more beneficial way of accessing these lines, because now, for example, what I can do is instead of printing out everything, I can do the following. Let's say, what does this do? Think about it for a second. This, for example, could provide us with only the first five lines in our code from 0,123.4 What is this? I want you to tell me. I want you to think about it. What is this element right here in our poem? Well, obviously it's this line right here. We have the first line, second line, third line, fourth line. And this one is just a new line and it's actually an item in our list. There is something to consider about this way of reading from a file. That is, if we have a huge file file with millions of lines and all of those have to be added to the list, it can break our code at some point. Let's look at the read function, which is maybe slightly more efficient but still not the best in here. I'm going to say actually it doesn't like that, so I'll do it from here. I'm going to say that the text is equal to poem, read, read, lines do read. I will comment these out as well. In here I'm going to print out the type of text. I will print out the text as well when I write, click and I run. This is what I get. If I hover over the read, will it give us any useful information this time? Apparently not again. No worries. I'm going to type in read in Python. Three schools again, schools. Let's see. All right, let's read a little bit about it. The read method returns the specified number of bytes from the file. Default is minus one, which means the whole file with the read, we can actually specify how much we want to read from the file. For example, 33. I'm not going to delve too deep into it. Is slightly more efficient than the read line since it creates a single string of the output and you can determine how many bytes you want to read from that file. But it's still inefficient for large files because it reads the entire file into memory all at once. The last reading method that we're going to look at is going to be a challenge for you. Your challenge is going to be to read striped lines. You'll need to use read line instead of read lines to read a single line from the text file. Again, I recommend that you look it up in W three schools, then find a way to print out these lines without a special character. And I'll give you a hint. If you don't want the hint, pause the video right now and go do the challenge. If you do want the hint, use the strip on our read lines and then, or on our red lines and then print them out. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? It shouldn't be too complicated. I will comment this line out. I'm going to say that line equals Python poem read line. Let's just keep it at the read line for now. I will comment these out at a space. Then in here I will print out the line and print out the type of line. Before we do, I didn't talk about this line right here, the class is string When we did the text, when we did the read. So something to keep in mind. But now when I write click and I run, look at that, the class is a string. And we have in lines of code and sense text clear. So we read a single line from our text file. There we go. But you'll notice that we also have this extra space in here. And what is that? It should be clear by now, it's because of the backslash N or the new line. So how do we get rid of it? The strip, and now if I right click and run, you'll see that there are no spaces anymore. There we go by. Now this should all be clear. We can use also the while loop with the lines. For example, let's say we want to continue reading lines until we get to a line where we have the word tool. For example, I would do the following. I would do while true, I will keep reading a line, reading a line, reading a line until I print out the line. And I mean not until I will keep printing out the line. And then if I find if tool in line case fold, I will break now. Right click and run. And there we go in lines of context, clear, Python, beacons, deer, whatever a language elevate tool to solve complex problems. And then we stop. But obviously we still have, these are separate. Let me show you. There we go. They are separated from the original one, okay? That is basically it. Notice that if we don't add this parameter, this is one small little detail. If we don't add this parameter, if we don't specify the mode in which we're opening, it simply defaults to a read. And I just wanted to tell you about that. Thanks so much for watching. I hope you enjoyed. I don't think it's too complicated. I don't think we need to delve too deep into this. In the next video, we're going to be looking at stripping and understanding better how it works. Thank you for watching. See you in the next video. 123. 3. Stripping Text Files: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at stripping text files. Let's go ahead and get started. First of all, I'm going to create a new Python file and I'm going to call it the Stripping underscore Text Underscore files. In here, I'm going to say string equal to and I'm going to add 123. Hello world, 123. As you can see, I have three spaces on each side of the Hello world. In here, I'm going to print out original string, two space, even string if I right click, and this is the output that I get. Three spaces on the left hand side, three spaces on the right hand side. Actually, in here we have four spaces. Why? Because we have two arguments presented to the print which adds a space automatically. Next we're going to have the version we're going to have equals do strip. Then in here we're going to print out that the string two dots, close down, stripped right, click and run, and look at the output that we get only a single space because of the two arguments and no spaces on the left, the right. We've already seen this before. If we don't provide anything to the strip, it will simply strip out the white spaces or remove the trailing white spaces. Trailing and leading, by the way. Important keyword that we didn't talk about, the leading and trailing, and what does that mean? Well, because we don't just have the, we have something else. I'm going to say left underscore stripped is equal to the string L strip. Now when I print out the left stripped string, left strip, you'll see that now when I right click and I run, it looks as if the output is the same but on the right hand, on the right hand side we still have our spaces. This separate things from the left hand side. If I hover over the left, it returns a copy of the string with leading white spaces, removed the ones that are on the left. We have the same thing happening if we do the following. I do this and I say in here, right are right, right. It should be obvious by now that it only removes the trailing or the spaces on the right hand side. Now we can use the strip method to remove certain characters as well. I'm going to be changing the code in the appropriate places. I recommend that you copy this space in here and then make the changes and comment out the old ones just so you always know the flow of things. But it's up to you. You can do it however you want. I'm going to add three pluses on each side this time. Now if I do the following, add a plus in here. Let me copy this. Paste, Paste, right click, run, and there we go. You can see on the original string we have these pluses on each side. In the stripped version, we don't have any pluses, neither on the left nor on the right on the string. We have them, we have them on the left. I don't think there's any confusion in here. I think this is pretty much self explanatory. I'm not going to delve too deep into this, I'm going to move on because there are a few intricacies that we need to understand about the strip in here. If I add two minus signs and then I add a minus sign on the left hand side. Now we have a bit of a mix. Let's try to strip these things. First of all, I will try to strip the plus and minus on each side. If I write, click and I run, you'll see that the minus and the pluses have been stripped on each side. But on the left and the right, nothing has happened because I'm simply stripping the plus. Now you might be saying, well wait, why isn't this plus being stripped? Hmm. Interesting. And it's definitely a very interesting question to ask. And that's because of the nature of how the left strip and the right strip work. So I'm going to be testing a few things out. Let's say I add a plus equals on the left strip, right click, and I run look at that, it all disappears. Why is that? Because even though in here I have two minuses and then a plus, it doesn't matter. As long as there's a minus in here. It means that a minus will be removed. And it will keep going until it finds a character that it cannot remove. What do I mean by that? If I add an H in here and I right click and I run, you'll see that Hello world, or the H and hello disappears. If I now try to add an L, do you think the L's are going to disappear? No, they don't. Why is that? Because as it was going, as the strip was looking, It's plus. Okay. We don't have that. It's minus. It's like. All right, perfect. Let's remove the first minus. Another minus. Let's remove it. A plus. We do remove A plus H. We do remove an H. Now we're at. Okay, Do we remove an No, we don't remove an All right, that's enough stripping for now. What we can do is if we add an right here, boom, you'll see that now does disappear. Can you see it? Now, the disappears and the L's disappear. If I add an X in here, for example, it's still the same output. So it doesn't matter in which order we break, as long as the letters in here are continuous. Meaning that if we don't have an E, then the L's are not going to be removed. Why? Because as the strip is going through the string, it arrives to H. Okay. H is there, We'll strip. It is not, therefore stripping, so we stop. I hope that's clear. The same is true on the right strip. Now, I don't have a challenge for this video, but as a mini challenge. As a challenge, or let's call it an unofficial challenge. I recommend that you try and test out a few things here on the plus. So for example, if I do a minus plus, what do you think the output is going to be? This is a challenge. Please try to think about it. There we go. Of course, it disappears because we start with a minus and it sees a minus, a plus, et cetera, et cetera. What do you think will happen if I do the following? Right click and run, and you'll see that nothing happens indeed. Because remember we're going from the right. What if I do A also? Nothing happens. Click run, nothing happens as well. But now for the last one, what would happen if I add an exclamation mark? And boom, there we go. Because we've removed the minus and plus. We found an exclamation mark, removed it, found the D, removed it, and then we encountered an L. Do we remove it? The L. No, we don't. It means that we move on with our life. Thanks so much for watching. I hope you enjoyed the strip is not something that's super, super crucial, but if you ever encounter it when reading from a text file, it's very important that you know how the strip operates. If you ever want to go back to this video, rewatch it, re, understand it, try to test out different things in here. See the left strip, See, see the right strip, and so on and so forth. Thanks so much for watching, and I will see you in the next video, where we will be looking at parsing data in a text file. Bye bye for now. 124. 4. Parsing data in a text file: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at parsing data in a text file. Whenever we want to get data from a file, we first need to understand what that data is or what that data looks like in that file. The most important is to understand the structure of said data. Making sense of the data is parsing, for example, the code that we're typing in right now in the computer, like the strip and the equals and the whatever, all of that is parsed by the computer or by the IDE into one and zeros to really understand what is happening, sent to the processors, then given back to us and so on and so forth to create the output. In this video, we're going to be looking at parsing data. Let's go ahead and get started. First of all, we need to provide the peoples list dot. Now I already have this file right here. Peoples list dot, There we go, People's list. I keep doing this. Please let me show you what I did wrong in here. Right. Click open and explore, and we should see this right about here. There we go. Then in here, I actually moved it. I shouldn't have moved it, I should have copied it. Let me copy back the Python poem into my resources location. And then copy the people's list. And paste it in here into the reading and writing files. There we go. We have the people's list. Let's open up the people's list. And let's see what we have in here. As you can see, we have a list of people, but not just people. We have the ID name, department salary, and the job title. You can see the ID's on the left hand side, one for John Doe. His name is John Doe. He works in the Department of Sales. His salary is 5,000 I don't know what. And his job title is Sales Manager. Then we have Jane Smith at ID two with a department that is missing. And this is going to be an issue for us, this is what we mean when we say part data. Because sometimes the structure of the data can be corrupt. Some things could be missing, like the department of Jane Smith. And then we have the salary. And the title marketing manager, Mary Brown for example, doesn't have a salary. And so on and so forth. So let's first of all understand how this data structure works. Because, look, we have pipelines instead of spaces. This is more akin to a CSV file, and we'll look at CSV files later on. But for now, this is a text file, we need to extract information from it. Let's go ahead and create a new Python file that is going to be parsing underscore people. Parsing underscore people here. I'm going to say that the file name is equal to people's list of Xt. This is a handy way of using the file name and not having to type people's list. Every time I will say with open file name, as people file, I will say four row. Now we're working in rows. You can call it lines, you can call it rows, You can call it x whatever you want. Just know that it's the row or the line four row in the people's file. I'm going to say that the data is equal to split over the pipeline. I'm removing the pipeline, or actually I'm splitting on the pipeline. And I will print out the data just in case you're not sure what the split does. I recommend you go through W, three schools or you can look at the documentation right here returns a list of the words in the string, using the separator as a delimterliit between the split between the pipeline. In this case because we've provided it with a pipeline and we're printing out the data. If we run the code, there we go. You can see that each individual has been added to a list and for example, the ID is one or the ID is an item. The name is an item. The sales are items, et cetera, et cetera. And then finally, we have this symbol right here, which is not good at all. So it's time for a bit of a challenge. And your challenge is going to be to remove the unwanted symbols. First of all, use the strip function. Then make sure that to only remove the new line character because we don't want to remove anything else. Also you can use both the right strip and the strip. Choose whichever one you want. Positive video right now and go do the challenge. Welcome back. How did you get on with that in here on the data road split? Now, the challenge here was to know should we split and then strip or strip the split. Well, it's going to be strip, strip the split I'm going to strip oh, no, this actually is bad and then split on the R strip. I'm going to strip the backslash N. I'm going to do a right strip. It's the same. It doesn't matter if you do the entire strip or the right strip, as long as this symbol disappears. Let's look at representing this data in a better way. Meaning that I don't want to have all congestion congested here. I want it to be represented in a more sophisticated way. Which means that we want to actually split up this data and more accurately unpack this data. So instead of just printing, I'm going to say that name or actually ID, let's call it per sono, underscore ID, name, department, salary, and title are going to be equal to data. We've already seen what this does. This is called unpacking data. We're unpacking the data in data into each of these variables right here, the ID name, department, salary, and the title. Then I will print out personal ID, Let's say I want to change their order, salary, job title. We'll create a separator which is going to be, first of all, a new line, and then a back back. Do you remember what the backslash S are? Do you remember the backslash N? Because we've done it recently. But the back, what is it? I'm not going to tell you. You'll have to do the research. Right click and run and look at what we get. Of course, this is not the best way to represent our data. I know, don't hang me for that, but at least it's slightly better. You can see that we have the name ID, department salary, and job title. Then we have John Doe ID one, sales salary, job title, Jane Smith, ID two. Hmm, Nothing in here. The problem, this is a problem because we have these empty fields fields. We will deal with that later on. But for now as you can see, we've created a better representation. And you'll see that there are a lot of missing things in here. Some people really don't have all of their stuff together, So now we want to add that information into a dictionary. And for that we need to get rid of the first line which indicates what the data is, meaning that in our dictionary, I don't really want to see name, ID, department, salary, and job title. That's not something that I want. Think of what we can do in here. How can we do this? Well, it's very simple. Some of you might have overcomplicated this in your head, but it's very simple. All we need to do is we need to say people's file read line. Now if I write Click and I run, I go to the top, you'll see that I no longer have the name ID department. And why is that? It's because the file is able when we do a red line, it's like we've already handled that first line and now we're onto the other lines of text. What I mean by that is okay, wait, we can work with this one. Let's imagine that when we're reading from a file, it's like a robot. The robot is a small, tiny robot. Stands right here at the start of the line. And it starts like this. It reads character by character. But the robot, if it wants to go back, it cannot just jump to this part right here. The robot needs to go back step by step. Actually, the robot cannot go back that easily. The same thing holds true with the read line. When we've opened the file and we're reading from it, what happens is the robot, when we do the read line, just reads the first line. Now when we do the four row in people, when we get to this line of code, we actually start from here because we've already read the first line, for example, as a test, what if we don't want to include John Doe? We duplicate this line. And now we start from Jane Smith. Because we've read John Doe. This is very crucial to understand about reading and writing to files. It will come up a lot down the line. So make sure that you've understood it right here, right now. Now, now that we've read through the first line of code, we made sure that we don't have the name department and whatever we want to add these into a dictionary. Instead of just printing them out. I will comment this out here. I'm going to say the people underscore dict is going to be equal to the following. We'll have to do, well, the ID to do personal ID. You're pretty familiar with dictionaries at this point. The department two dots, department salary. Two dots salary. Actually you know what, I don't like having these capitalized except for the ID. Let's take these down to the lower case. You'll see why later on. It might cause problems when we're trying to access these keys. Job title is going to be the job title. I will add a because I can. Then I will print out the People's Dictionary. There we go. Now, let me move this down. I have a feeling we will need a longer tab. Right click and run. There we go. You can see that we've simply added Justin Lee ID, which is the last person which is not good. Obviously, this is not what we wanted. The reason why this is happening is because if we look closely, we have a people's dictionary. It's only a single dictionary that we keep adding. The personal ID name, department, salary, job title, two. And remember, dictionaries are mutable. We cannot have duplicate keys, so the values keep updating. And the last one to get updated is the actual last person that we have in the list. So when we get to Justin Lee, we parse the data, we put it in the People's Dictionary and we get the name being the name which is Justin Lee, ID, et cetera, et cetera. In the next video, we're going to be using the sparse data and actually putting each one of these into a big dictionary. Thanks so much for watching. I hope you enjoyed and I will see you in the next video. 125. 5. Using parsed data: Welcome back my favorite Python programmers to a brand new video. And this one we'll be using parsed data that we've extracted in the last video. So now that we have our data properly parsed and extracted, after we are going to put the data into one big dictionary, currently we have these dictionaries. Oh, and by the way, if you look at this output, and where the hell did this come from? I was just testing something out. You can actually move this print into the fore loop in order to see all of the names. As you can see right here, they did not show up because what we did was we printed the People's Dictionary outside. That's why it was the last name, which is Justin Lee. But if you want, you can print it on every single line. And it just occurred to me before starting this video, I tested it out. Maybe this is a better way for you to see things better for you to understand. I'm not sure. I hope it does help. Let's now put all of these into one dictionary, with the names being the keys. So we'll have a huge dictionary, which will be the people's dictionary. We'll create like a people right here, which is going to be equal to an empty dictionary, and we're going to be putting these names into the people's dictionary. So these dictionaries will become the values, and the keys are going to be the names of the people. Then we can access these names in a meaningful way. Let's go ahead and get started. First thing we're going to do is we're going to actually start putting these into the people's dictionary. After we print out each person, I'm going to say people, open up this and say name case fold. It's not allowing me, but that's okay. Named case fold equals to the people. Dict or dict. Then at the end I will print out, sorry, print out the people. So when I write click and I run, look at what we get here. First of all, we're printing out the names as usual. And I don't want to do this actually, let me comment this out so that we know exactly what we're getting. Okay, so look at this dictionary. Let's start from the beginning. First of all, we have the dictionary starting. Then we have the key, which is the name case fold right here. And I make sure that it's case fold because I don't want to have any mistakes with the upper case and lower case and so on. Let me make this smaller. We have John Doe being the key. And then inside we have all the information about John Doe. We have his name, ID, department, department, salary, job title. And then we close down. So this is the value, this is where the value ends for John Doe. And then we have another item in this big dictionary, we'll call it the People's Dictionary. And then we have Jane Smith. And Jane Smith is the key. And Jane Smith has a value of the dictionary that contains the name ID, department, salary, et cetera, et cetera. Now we have a big, big dictionary that has the key as the names of our individuals. And then the values are dictionaries with the information about these individuals. Now what we'll want is to have a way when a user, let's say me or you. When a user inputs the name of a person and gets their salary. And this is going to be a challenge for you. You need to get input from the user, which will be the name of one of the employees. Make sure the name is case, Fold check if the person's name is in the dictionary. This is the first things first, and if he exists or she exists, extract the salary field and print it out in a user friendly, a positive video. Right now, this is a hard challenge, especially if you're not 100% sure of your skills in dictionaries. But it's a very important challenge. If you can do it, that means you have dictionaries on point, positive video right now and go do the challenge. Okay, welcome back. So first thing we'll do is I don't want to print the people anymore in here. I'm going to say person underscore name is going to be equal to the input saying provide the name of the persons, person's person's salary or person's salary, sorry, provide the name of the person's salary, you'd like to look. Up and then we'll simply do this, this is going to be the input then I'm going to say underscore key is going to be the person's name fold in case someone, because you know, usually when you write somebody's name it's going to be capitalized. But in here, remember these are strings, they are unique. They are key sensitive. So we make sure that we take them down by the case fold and then we will check if we actually have this person in the dictionary, how did we use to do that? We simply say if key in people and then we'll say person is equal to people at the person key and then person's salary. Salary. No suggestions, Yes I know is equal to person at the salary. And print out the salary of replacement field person name is person salary. I keep forgetting the And salary. Now if we don't find the person, we'll just print out person salary. Sorry, person name is not in our or is not an employee here. Okay, I don't know why we need the explanation mark, but there we go. So let's go over what's happening in here. First of all, we're getting an input, very simple. Then we're doing a case fold. It's important here that we do the case fold on a separate variable, otherwise the name of the person will be printed out in a lower case here. And that's not very user friendly. We want the names to be in their upper case. That's why we created the person key a separate variable. To check this, then we use the person key. We check if the person key in people. We're checking if the key is available in our person. If it is, we'll do the following. If it's not, we'll simply print out it's not an employee. Remember when we do if a key or if person key in a dictionary. We're going through the keys. We're checking the keys, not the values. We're checking if we have John Doe, or if we have Jane Smith, whatever the name was, then we grab the person. We say person equals people at that key. So for example, if the person key was Jane Doe, then we grab the value and we put it in the person variable. Then we say that the person's salary is going to be that person. Because remember, this is also a dictionary and we grab the salary. It shouldn't be too hard, especially if you understood what was happening in dictionaries. It shouldn't be hard at all for you. First of all, we check if that key is in our people's dictionary. If it is, then we grab the person by their key. Once we grab that person by their key, we grab the salary by the salary key. Now if I write Click and I run, If I try, let's say Michael. Nope, Michael is not an employee here. Let's run this again. Let's say I try John. Let's say we type in John Doe like this. It enter the salary of John Doe is 5,000 If I go back to the list, let's see. John Doe does indeed have a salary. Let's try Steve Kim. He makes a lot of money. Steve Kim. Let's see how much he makes. So if I write the click and I run put Steve, there we go, Steve Kim. The salary of Kim is 7,500 All right, very nice. This seems to work. Before we move on, let's suppose that we'd like to look a person up not by their name, but by their ID. We have two solutions for this. Either we can create a second dictionary with the keys being the ID. And then we can check for a few things, but there is a better way. And that is actually adding another key to our people's dictionary, which is going to be the ID's For that, we can simply come in here, duplicate this, and instead of name dot case fold, we can do personal ID do case fold even though we have numbers, so it's not going to matter. We put them in here. If I try to print out the People's dictionary, look at what we get. John Doe. Okay, The information is still the same. But then we also have one and we also have the information. Now we could, for example, say provide the name or ID of the person's salary you'd like to get. When I write Click and I run. For example, let's say I want the salary of the person with the ID 11. Boom, enter the salary of 11 is 4,000 Obviously, this is not very good. What we can do for example in here is get the underscore name. We already have the name, Let's call it the person info in here. Change this to info and then, okay, seems to be good. Then we have the person name is going to be equal to the person and we're getting the name. And then in here, person name. Because we're doing this outside, it's not going to get recognized. Maybe we could create a like a function for this. For now, let's just keep it as it is. Let's just keep this as the key. All right, because we don't want to have duplicate codes. We could create a function that would get the person name and salary. But for now, our focus is to actually get this, for example, 11, Chris Lee. Let's look if Chris Lee is indeed at 11. Yes, there we go. Chris Lee is at 11 with 4,000 Ladies and gentlemen, I want you to really feel how much we've progressed. We've parsed a file, we've got all of the information, we've put it into the first dictionary, and then we put it into the big dictionary, which is the people's dictionary. We've used two keys in here. We've used their name, and we've used their ID, and now we're axing all of that information. I mean, this is great stuff, this is high level stuff. If you're not really sure about what's happening, please please, please take your time. Go back through the code, understand every single line. If you have any questions, make sure to ask me or your dedicated instructor that you've been assigned to, they will help you through this process. Thank you so much for watching. I hope you enjoy it. And I will see you in the next video, where we will start writing data to a file, not just reading. I will see you then. 126. 6. Writing Data To a File: Welcome back my fellow Python programmers to a brand new video. And in this one, we're finally going to be looking at writing data to a file. So the first thing we want to do is we want to save some animals. Yes, indeed. We're going to create a new Python file that we will call Save underscore animals. So in here I'm going to provide you with a list of animals. Don't worry, I hope I don't forget to provide. If for some reason I do forget to provide it somewhere or the way that I've provided it is not adequate, Please send me a message, send your dedicated instructor a message and we will get to you. But in any case, this is the animal data that we have. Now what we want to do is not save all of these animals in Peta does or whatever animal organization there is, We're going to actually save it to a Txt file. We're going to first of all name this file, which is going to be the animals underscore file name, is going to be equal to animals underscore printxt. Now you might be wondering, we don't have the file right here in the projects. Don't worry. The file will be created when it's needed in here. I'm going to say with open animal file name now, instead of the R, we need to provide it with the W indicating that we want to open the file in write mode and we're going to say as animals underscore file, this is the where we will be writing. Keep in mind this is only the name, the animals file name. This is the actual file object that we'll use to write two in here. I'm going to say four animal, Yes, in animals data. I'm looping over this list from top to bottom and what I'm doing is I'm printing out animal file, equal animals file. There we go. As you can see, this is something that we haven't seen before, but I'm going to take you through it. First of all, if the file exists, meaning that animals underscore print or the animals file exists, it will be overwritten. If it doesn't exist, a new file will be created. That's 12. What is the file equals right here? This is an extra parameter given in the print. The file parameter in the print function specifies that the output should be written to the file object, which is animal file right here, instead of the standard output that we see in the dropdown menu or what do you call it, the console or whatever. So when we say file equal, it means the output will go to that file. Now let me open up the project so you can clearly see. We didn't have any animals print. When I write, click and I run, Boom, there we go. Now we have the animals print right here. And if I open this, notice I don't have anything printed out to my console. It's all in the animals print. If I double click and open it up, I have it right here. But let's imagine we've written to a file and we can't really open. This can happen in many cases, especially when you're using special encoding. Let's say we want to actually open this file and see what's inside. To check if we were able to properly write to it in here, I would just say new underscore, animal underscore list is equal to this empty list. And I'll say with animal file name as the animal file, you can use the same name. And here, don't worry, it's not a huge deal. We've already closed this file, remember, because we're using the width. So we've closed this file so we can use the same file name. It's okay. And in here I'm going to say four animal. In the animal's file, Animals file, I'm going to say new animals list append with the animal. Now, there is one thing missing in here and I want you to tell me, it will be obvious, but I want you to think what's missing in here. What have I left deliberately out. If I write, click and I run, look at what I get my list. But what do I have in here? I have my new line symbol. How do I solve this? Take a few seconds, think about it. Yes, exactly. I can hear you on the back saying the strip, when we do this now it works completely correctly. Okay. It's pretty similar to what we've been doing before, but there is a different way of storing data in a text file and that is using the right method. So let's do that. I'm going to go back in here where we've written the data. And I will comment this line out right here. I'm going to say animals file, right then I will write the animal into it. Now keep in mind we already have an animal's file. What happens when we already have one? It will be overwritten. When I write Click and I run look at that, my output is a bit different and this should give you an indication of what is going to be in our actual file. Look lion, mammal, and then we immediately start with Eagle. Notice we have a list of one single item with all of the names of the animals mushed together. If I open the animal's print, you'll see that this is how it looks. The only difference, or the main difference between the print and the right is that the print adds a new line character by default, while the right does not. Let's look at another thing that the right cannot do. My words are getting confused. And when I say we or let's, I'm saying let's see, You see what? Okay. I'm not good with words today. Just write ten numbers. Write the first ten numbers, one through ten, to a file called the numbers file. This is something completely different. If you want, you can even create a separate Python file for this. Actually, it's a good idea if you create a completely separate Python file for this. First, you must open the file with the W, of course, with the W mode inside the width create a loop in the range of ten. This with means when we say with open, et cetera, inside the width. Create a loop in the range of ten. And use the print and then the right functions to write the numbers to our file. This is a challenge for you to try out writing to a file using the print and the right, you know the difference, You know how this goes. Positive video right now and go do the challenge. Okay, welcome back. How did you get on with that? I'm going to create a new Python file in here which is going to be right numbers in here. All that I'm going to, I'm going to say numbers underscore file name is equal to nunscorefilet. I'm going to say with open numbers mode as numbers underscore file, we have the same name number file. I think we can use that no problem. And I'm going to say four in range. And this is the loop that I told you about that's inside over ten. I will print and then file equal numbers. File, there we go. And add an extra space at the bottom for the eight. Now if I right click and I run, I get the numbers file which is zero through ten with an extra space at the end. Neat. But now I want to use the right. And I don't think there's anything that I need to really explain in here. The for loop. We've already seen that. We've seen how to open a file to right. We've seen how the print operates. There's nothing else to explain. All that there is to is to use the right. So I will say numbers file, right. And then I'm writing V, I right click, Run, and we get an error because I argument must be STR not an integer. Not that the right method will write only what you tell it to write. No conversion is performed, and obviously when you're writing to a text file, it shouldn't be an integer. It doesn't understand integer. There are ways of converting. If it's not dot, for example, you could do a conversion. Why use right at all? Why use right in the first place if it's so bad? Well, it depends on the situation you're in and how you want the data being written into your file to behave. So for example, if you need more control over the data that is written or if you need to write, for example, binary data to save as much space as possible, then right might be the choice for you. Meaning that maybe you don't want to add an extra line but but the print forces you, maybe, I don't know convert things. Maybe you want them to stay the way they are filed. Again, print does not allow you. If you want more control you would use the right. If you're just writing something simple to Txt file, then using the print would be your choice. In this case, I would use STR to convert the right click and run, and I still get a bad output. And the numbers file, they are all mushed together. How do we solve this? Take a few seconds, think about it. What should we do? There we go. And we have this output. Ladies and gentlemen, thank you so much for watching. I hope you enjoyed. In the next video, we're taking things to the next level where we are going to be learning all about Jason files. So thank you for watching. I will see you and the next one. Bye bye. 127. 7. JSON files 101: Welcome back my fellow Python programmers to a brand new video and probably a long one, where we are going to be, first of all, explaining serialization and what it is we're going to be explaining what Json file are, Jason files are. We're going to delve deep into them, test them out, so on and so forth. Then I'm going to also show you how to write and read from these files and we'll see a little bit about encoders and decoders. Let's not waste any more time and let's go ahead and get started. First of all, let's look at serialization. What is serialization? Serialization is the process of convert and objects state to a format that can be stored or transmitted. For example, if we're sending information through Bluetooth, the information doesn't get sent as in strings or couples or whatever. They are sent through waves and zeros and ones. That's how they understand the stuff, that's serialization. When writing to a file in Python, serialization is often used to convert an object into a text representation that can be written to a file. To write representations of the object to the file, we use the function dump. We dump the information in there. There are many ways of serializing data and one of the most widely used is the Chason file. If you're thinking, whoa, this is too complicated and whatever, don't worry. For example, when we were trying to write a number to a file in the previous video, we had to convert it to a string and then add a new line. And that is what we call serialization. Seralization can come in many forms. It could be very complicated, and it can be very, very simple. Just like we saw in the previous video. Now let's look at what Json is. Json is Javascript Object Notation. It's a format commonly used for website application or web application. Not just a website, but anything that you do when you're interacting with the World Wide Web uses Json serialization. In the context of the Json files refers to the process of converting a Python object into a Json encoded string that can be written to a file. We have an object and Python we encoded using the Json. And then it's a string that can be stored in a file. When we want to use Json, we need to import a module, just like we import the random. When writing a Python object to Json file, we use the Json dot dump, we've already seen in the previous slide. When reading a Python object from Json file, we use Json load. Not all Python objects can be serialized to Json format. We'll see a lot of examples. But for example, the set cannot be serialized to Json format. And Jason serialization and deserialization is faster than other serialization formats like XML. We were not going to go into XML in this course unless I, for some reason decide to update it and use XML. But Json serialization and deserialization is the more commonly used one. You've probably heard it before and it's what we are going to be focusing on, enough theory. Let's go and look at an introduction to Json files. First of all, I'm going to create a new Python file in here which I'm going to call Jon Underscore Intro and I'm going to right click on Json intro and I'm going to close all close other tabs so that we only have a single tab. Close this down as well and maybe keep this one right here. The projects, just so if we have any extra files added so we can see them. I'm going to import the Json, as I told you, it needs a module and then I'm going to have computer underscore parts. I'm going to have this list. Now, again, I'm going to provide you with this information, don't worry, it's just a list of these elements. 198, it's the year where the hard disk drive was created, the random access memory, the Ram 1968, et cetera, et cetera. Now what I'm going to do is I'm going to write this to a Json file. I'm going to say with open and I'm going to do the following. I will say, Jason underscore score, just test file dot Json to make it an actual Json file and then as Jon underscore test file. Then in here I'll say Jason dump and I think, yeah, no, it's okay. It's okay for some reason. I thought maybe it interpreted it as the folder here, the entire module. I mean, then I'm going to send in the computer parts into the Json test file. And you can read all about the dump and how it works. You can see it send a very extensive function or method that you can look into for me. All that you need to know is what you are actually sending in, what you want written to and the file you want things to be written to or the data to be written to. Now if I write, Click and I run, look at that. A new Json test file has been created. If I open it up, look at what I have. I actually have a list. But there are a few limitations to Json and we're going to see them. But before, let's look at what happens when we want to read data from file. If I go back in here, let me comment this out because I don't want to write again. I'm going to do with open and then, oh my God, I hate this by the way. I hate this and I don't know how to get rid of it. Json test file, it will default to writing and it's just going to be the Json underscore test file. And then the Jon underscore data will be equal to Json load. And we've already seen and notes we have loads and load and we will see the difference Json test file. Now if we try to print out the Json data, right click, Run, boom. Look at that. We get all of the data still in the form of a list. Let me try to print out the type of the Json data. Right click, there we go. It's still a list. So keep in mind, we wrote into the file as a list, it was serialized by Json and now it was deserialized. And it kept its integrity, it stayed in its four. This is something very important to keep in mind when we did it previously, when we serialized, for example the integers, the numbers 0-10 or 0-9 in the previous video, they were converted into a string. If we tried to read it again from the file, it would be a string. But in this case it kept its integrity. We can even, for example, axis the data at position number two. If I write Click and I run look at that, I get the central processing unit CPU, which was made in 1971. This all looks fine, but there are limitations to what Json file can serialize and serize. Let's take a look at this limitation. First of all, what we want to do is we want to convert all of these into pupples. Now, we could come in here and start adding this, and then, oh, wait, it changes automatically. I think, yeah, we can do this. I wanted to show you a nifty way of doing these things, but unfortunately, it just showed what? Let's just do it. If you hit, for example, control R, R. You'll see maybe just one control R, one control R. For example, you can say that find all of the square brackets. It will find them and convert them into round brackets. You'll see it will give you where do you want to convert? You can, for example, select this one and say exclude, exclude this one, and replace all. Boom, there we go. You can see this one. We don't want include replace all. Okay, there we go. Now we can select this side. We can click in here and ex, then convert it into the. Boom, this one. Replace all. There we go. So we've converted this into a topple. And by the way, this wasn't present a few months ago when I was working on the scores. For some reason, maybe in the update they included it. But anyways, what we want to do is we want to convert these into topples. Hitting the control R, you can select what you want to change and then exclude the things that you want to keep. Very, very powerful tool, by the way. So now that we have these in the form of a couple, I'm going to, Let's keep it, let's keep the read, and let's comment this one out, meaning that we are going to write again. Now if I write click and I run, what do I get? I still get a list. If I open this file, I still have a list. But guys, this is Apple. Let me write, click, and run again. It's Apple. What is happening? Well, it's the limitations that Jason faces where it cannot serialize topples. Let's look at a few things that it can and a few things that it cannot. If I open this and don't worry, I will send you the link for this. This is the Jason. Jason encoder and decoder. If you scroll down, you can read all about this, how to use this, go super, super in depth, but I don't want to waste time on that for now. I want to look at encoders and decoders, the Json file in here, you'll see that performs the following translation in decoding when you want to decode. If, for example you have an object, it becomes a dictionary. If you have an array in Jason, it becomes a list. If you have a string, it goes out as a string in Python, and so on and so forth. If we scroll down to decoding, I mean encoding following objects and types. By default, for example, a list and a couple are converted into an array. An array in this case is just like a list. It has square brackets. A string stays a string, but an integer float integer, and flow derived enums, whatever are stored as numbers, true stored as true, false as falls, and none as null in a Json file. That is why when we converted in Python from a list to a couple, we still got an array and we still had the same output. So I hope this was understood, I hope this is not too confusing. You can always look back at this and understand how it works, But using Jason files is super, super important. For example, if you want to save dates into Jason files, it's impossible, They are not registered properly. Jason has its limitations. Anyways, I know this video has been long. I try to be as brief and as in depth as possible. In my explanations, I think I covered everything that I needed to cover. To give you a broad idea and a little bit more in depth idea. I do recommend if when the time comes when you become the data analyst or the Python developer or whatever, you will have to delve a lot deeper into these things. I'm not going to do that in discourse for now, Maybe later who knows. But let's now look at a practical application of using Json. Back in here, I'm going to create a new Python file. Sorry, not a new Python file. A new just file. And I'm going to call it students. Jon, I want to have a Json file created. Then I'm going to put this data in again, please. You should see it somewhere. If you don't nudgeI don't know if you remember nd MSN, I don't know, how old are you. Maybe what I just said makes no sense at all. But anyways, look at what we have in here. We've created a Json file and intelligent recognizes that we've created a JSon file. Maybe on your side it does not recognize this. Maybe you have to install something that pops up on the bottom right corner. Do whatever is needed. You should see this color change. So notice what we have in here. It's kind of a dictionary, if we look back at this right here. So we have object, right? So this is an object because Jason doesn't have a dictionary. Now in theory, what should happen when we convert this or when we read from the Json file, We should get dictionaries. So keep that in mind because we're going to create a new Python file that is going to be practical underscore Json. And we're going to issue you a challenge where you need to load the students. First of all, import the Json module, open the students folder in the correct mode, load the data into students variable to a students variable. You can call the variable whatever you want. Keep in mind you have to load, print out the data that you get and does it look user friendly? Can we do it in a better way? Pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? First things first is importing the Jon. Right? And I know some of you at this point are complaining like these challenges are getting really, really hard. But what I'm imagining you as is you've already done like maybe ten, maybe 20 hours. I don't know how long this entire course is, but you've done so many hours, you should be very, very familiar, especially if you were working with one of our instructors. You should be top notch. So you should be attacking these challenges without any mercy mercilessly. So I'm going to say with Open. Oh my God. Students Jason, I want to be faster than the other one because I emphasized using the right mode. I will do the R as students underscore file and then in here I will have students and I will say Json load and we will load the students file. That's it. We've already seen the load. We've already seen the Json module. We've already seen most of the things that we talked about. All that's left to do is to print out the students and to print out Wait. Before we do that, first of all, we wanted to look at the students and what we get and look at that. These are what, let's say we don't even know. Let's not assume anything. These are dictionaries. Indeed, if we wanted to print things out in a more user friendly way, how would we do that? What do we have in here? Look at the data and understand what it is, parse it, really understand how it's looking in this file. What do we have in here? We have the key students and then we have name, a major, et cetera, et cetera. These are our students. The key is student. The value is a list and it's a list of dictionaries. So for example, how do I access, how do I go deeper in here, I print out students, students, what do I get? Boom, I get a list. How do I delve deeper? I open up the first element inside of this list. I get this dictionary. I get the name John. How do I access this even deeper? I want to get the name, for example. I get John. Again, practice this. Make sure that you've understood how this works. There is nothing to this. I'm just going deeper and deeper. Actually, let me duplicate this so that you can see what I want to do. This one and then this one. Okay. Yeah, this should be good. Okay, so now let's maybe deerize this information and printed out properly. I'm going to let me first try to click and run. Okay, there we go. So we've created the steps. Now let me print in here. And I'm going to say students underscore data is going to be equal to students at the students in student data. I'm going to print out student. No, wait, this one should be a student because we're accessing each individual student. Student name is my God, what am I doing, years old and studies. And by the way, this was part of the challenge to print it out in a user friendly way. Studies student major, right click, run and look at that. John is 20 years old and studies computer science. Alice's 22 and Bob 21 and they each study mathematics and physics. Ladies and gentlemen, this was a very long video. I think we're at the 20 minute mark at this point, maybe even more. If you made it to the end, you are incredible. If you understood 50% of what just happened, you are doing extremely well. This is not easy. These are new concepts. Serialization, deserialization, Jason, reading, writing, load, write, dump, what the hell is happening? Don't worry, it's natural to feel like you're getting started. It's natural to feel that these things are hard. You're seeing this for the first time again. Breathe out. Go over the video, how many times you need extra resources. Go to W three schools. Make sure you understand everything. Contact your local instructor at Tm Python Dev. Make sure that they explain to you everything. Make sure that they help you out. Don't worry, it's very important what you did right here. If you can understand what happened, you are amazing. We serialized JS file, we deserialized AJson file, We extracted information from whatever this was. And look at what we got in the end. Look at what we printed out, this beautiful looking information. I don't know what that even is. We just got this. I hope you enjoyed. I hope it wasn't too confusing. The next video, we are going to be streaming Json file from the Internet, which is going to be very cool. Which is going to be like something like we do, for example in Netflix when you stream files. Thanks so much for watching. See you in the next video. 128. 8. Streaming JSON files using urllib: Welcome back my fellow Python programmers to a brand new video. In this one, we're going to be streaming Jason files using URL Lip. What does that mean? We're going to see in just a bit. But first we need to understand what is file streaming in the first place. You might have seen streaming in many places like Youtube, like Netflix. I don't know anywhere else where you've seen streaming. What is file streaming? Jason is a data format that is commonly used for exchanging data between client and server. So as we said, Jason is used very widely in web application. And when you are using the web, you are communicating with a server. So you have, let's say you've opened Facebook or Instagram or Twitter or whatever. When you're on your phone and on Facebook, let's say you're scrolling down or you're uploading a photo, or you're liking a photo, what's happening is you as a client, you are having an interaction with a Facebook server. So you're interacting with a Facebook server. So how does that data come to you? Some of it comes through Jason. So you're streaming that data through Jason, for example, or you're streaming that data from the Facebook server using whatever encoding that they use. Streaming files like streaming movies on Netflix, is accessing Json files online that are always up to date, and printing them out to an application for a user to see. So for example, you have the Netflix application, or you might open Netflix on Google Chrome. So then you are streaming the Netflix files to your computer. You don't download them. Remember this is not downloading. You are streaming, so you're getting bits and pieces of the file as you're getting them, you're displaying them on your application. R Lip is a Python library that is used for accessing URLs. It can be used to make HTTP requests and retrieve data from web servers. So HTTP is a way to create security, let's say HTTP request, how can I tell you? Like, for example, if we open again the link that we had in the previous video. Okay. All right, here, that continue. Right here, you'll see we have HTTPS right here. Let me check what it actually stands for. Control HTPS copy that, meaning hyper transfer protocol security. Basically, it allows you to create a connection between you and the server that you're trying to work with, that's HTPS. When working with Json data using URL Lip, you can use a stream to retrieve the data rather than loading all of it into memory. This is done using the URL open, which returns a file like object that can be read in chunks using the read method. Let's go ahead and stop with the theory and actually start working with streaming Json files back in our code in here. We're going to create a new Python file that I'm going to call Jon. Underscore file. Underscore streaming. Boom, here we need to import Json and we need to import UR lib request. This is very important. This is what will allow us to access websites in here. I'm going to say Jason underscore data. Underscore link is equal to the following link I will of course, provide to you somewhere. There we go. Now with that link, if you want, you can even open this link if I open this link. So this is the link. If you follow it, you'll find that we have a list. A huge list for that matter. Boom. Inside of this list, what do we have? We have this dictionary which has ID, name, user, et cetera. Then the address, the address has inside of it, another list, another dictionary. And I'm saying dictionary, but in fact, what is it when we're talking about this in a Json context, it's an object, not a dictionary. But when it's deserialized, it will be a dictionary. In Python, right here, there we go. You can see that the geo, which is a key inside of the address key, has its own dictionary in it. It's very important for you to go through this and parse it correctly. You need to understand what is happening here. But anyways, let's take this back here and let's go ahead and continue on. We are going to do the following, we're going to say with, and this is going to be new but not worry. Url, Lip request, URL, Open Json data link as Json underscore stream. Then in here I'm going to say that the data is equal to Json stream, read, decode. And it's not giving me suggestions. I'm not sure why user equals Json loads data. Keep in mind this is not load like we've done before, this is loads. If we hover over loads, okay, that's a lot of information. But basically what the loads, the difference between the load and the loads is that it allows for streaming. Can I find in this documentation somewhere that it says that this is for streaming? No, I cannot. I do recommend that you go and you look up this in more detail. There are more differences than just the streaming part print out and maybe we should do the users right click and run. What do we get? There we go. We get list for that matter. To look at this, the list which inside has the ID and the name, and the username, and the e mail, and then the address. And then the address is a complete based on its own. So a lot of data in here that's happening. And somebody has to decode it. And you know the drill by now. When I say somebody, it means you because you need to print things out in a user friendly way. You need to use the data that we got to print out a user friendly output. We want the name of the person, their city, and their phone number to be printed out correctly. We want this for all the people we have in the file that we streamed. Pass the video right now and go to the challenge. Welcome back. How did you get on with that? I admit this is not an easy task to do here. I'm going to say four or four user users. I'm going to print out the following if we just follow the example in here. First of all, what do we want? We want the name very simply. We're going to do the following. Open the parentheses and say, open up the brackets and open up the the brackets as well. What's the matter here? What is the problem name? What is it expecting from me? User parentheses. Okay. I think it's not recognizing. Let me try to run and see. Okay. Name parentheses, unmatched. I don't think it recognizes that. I apologize, this is embarrassing. I spent a few seconds trying to figure this out. Again, I like to keep these mistakes because you should always know that everyone does these mistakes, even an instructor. The problem was that when I used these two quotations and I was like, What's happening? Maybe Python isn't realizing that dictionary or I don't know, something is very, very wrong. The problem was that I was using single quotation marks around these and I was using single quotation marks inside. That was it. I spent, the editor probably edited that out, but it took me 2 minutes to realize this name. If I write Click and I run, there we go. You can see that we get all of the names. Very nice. Now they live in. We open this up again, You should know the drill by now. What do we next want? We want the city, correct? We said the city and their phone number. We want the city. Our stream right here. Now we found the name. It's pretty easy were accessing every single individual item in here. And then we access the name, we get the name, but then the city is inside of the address. First we need to access the address and make sure that it's written correctly. Let's double check. Where is it? Right here. Let me copy this actually and paste it in here. It's the same. Then we, the city, we click and not debug. If I write, click and let me stop this and run. There we go. Lee Graham lives in Gwen Burl Irvin. How lives in Wiscommb. These names are very weird. I don't know where they are from, but as you can see right here, address, address, city, and so on and so forth. Now, we want to also get the phone number you can call them at. Open up the parentheses, where is it phone? It's on its own. It's not inside of the address, so very easy to access. What was it? Phone. Phone, right click, Run. There we go. Now I'm getting the sweet symbol here. What is it? Oh, it's part of the phone number. All right, there we go. So maybe this was completely nuts to you. I think everything was easy. Maybe this line of code is weird. It's part of decoding, it's reading, decoding, and then loading into users. This should be pretty simple. This is new, but this is how we access, not files. We're not opening a file, we're accessing a stream here. These should be pretty simple. The hardest part, I think, in my opinion, the one you might be struggling with, is understanding how this operates. Take your time. Understand exactly what is happening in here step by step. Focus on one at a time. Just focus on Lea Graham. Focus on the ID, on the name, on the username, and email. Just for training, just as an extra challenge on the side, try to access the latitude. Okay, try to access the latitude that each person is working on. It will be a great exercise for you. Once you can do that, you are solid. In the next video, we're going to be looking at CSV files which are a completely different beast on their own. But don't worry if you can understand this. You can understand anything in life. Thank you so much for watching. I hope you enjoy it. And I will see you in the next video. 129. 9. CSV files 101: Welcome back my fellow Python developers to a brand new video. And in this one, we're going to be looking at CSV files without any further or let's go ahead and get started. First of all, what the heck is even a CSV file? Csv stands for comma separated values. It's a is a simple or CSV is a simple file format used to store tabular data. Tabular data means data that's in a table, meaning Excel. Google Sheets. Very important in data analytics and data analysis. It's often used for exchanging data between different applications, such as spreadsheets and databases. The CSV module provides functionality, provides functionality for working with CSV files. Just like we imported the JS file. In order to work with Json encoding, we also need to import the CSV. To read CSV files, we use reader function, which returns an object that can be iterated over to access each row of a file. We've seen how we access rows in a text file. The same holds true when we're using a reader on a CSV file. We access individual rows and each row is represented as a list of strings, with each string representing a value in the row. We're going to see more of that when we actually start working with CSV files. And finally, to write CSV files, we use the writer function, which allows you to write rows of data into a file. We're going to see all of that strap on your thinking caps and let's go ahead and get started. First of all, I'm going to go back into my code. In here I will create reading CSV file, Python file to a new Python file, reading underscore CSV, underscore files head book. Next I'm going to write, click and open and explore. I will go right here on the side, just like we've done before. You'll see that we have, we have this as well. We should have the resources. Again, if you do, if there's any problem, please let me know. We should have two ones. One is quoted, one is not quoted. And I'll tell you what the difference is. Control C control. And now we can start using this file. We should see Av file, Where is it? Where is it? Somewhere in here. Wait, am I just blind and I can't find it? Oh yeah. There we go. So the SV file. Let's open it actually, and let's look at what we have. So this is the comma that I promised you some versions of. Intelligent have seen it with students, maybe because of the update even though I keep this updated as much as I can. There we go. It's in the table format. Some of you might not have these in color or you might not have the option for table editor. I think somewhere when you try to open the CSV file, you'll have a pop up right here, or you can see CSV plug in. You need some kind of CSV plug in or whatever. Download it, Set it up so that you can see it in this format, just as I do right here. If I move this up a little bit, you can see that this is a table format or tabular data. So we can see we have names, the ID, department, salary, and a job similar to what we had with the XD file. But this time it's a little bit different with the ID's being these huge different numbers. Usually ID's don't come in 1-10 in order back in the reading CSV file. First of all, we need to import the module CSV. Next, we have to say that the CSV underscore file name is equal to the people list CSV Sv. Now, just like we do with every single other file we say with open CSV file name, new line, I'll tell you what this new line is in just a bit. As people or people underscore CSV, underscore file. Then we're going to use the reader because remember we want to read from this. We'll create a reader variable which is going to be equal to CSV reader and we're reading the people CSV file. Then we'll say four in reader print. There we go. So first of all, what is this new line? The new line parameter is used when opening a CSV file to specify how line endings should be handled when reading from the file. This is only special for the CSV. What do you want to have at the end of the line? And I told it that I don't want anything. So let's right click and let's run and look at what we get. So as I told you, it's going to be a list of strings with each separation between the com being an item of that list. So you'll see name, ID, department, salary, job title, John Doe, ID sales, their salary, and the job title, et cetera, et cetera. You'll see even some of these are empty. Now let's expand on our example and make it more suitable to read. We'll start by setting the headers properly. First of all, obviously I don't want the headers to look like this. I'm going to go inside of this file file and I'm going to say headers equal to people CSV file read line. I'm reading a single line and we always have to strip. I'm not sure what I want to strip. I'll just keep it as it is. I'll just say strip. I don't know what it will be. And I'm going to also split over via. Then in here I'm going to go ahead and print out the headers. I'll have headers, two dots, placement, field headers, right click, run and boom. Look at that. I have my headers. The only problem is that I'm not getting rid of these. It's still in the form of a list in here. First of all, I'm going to do a few strips. I'm going to do a backs R, which is called the carriage return and the backslash N. Let me just show you what happens with the backslash R. If I right click and I run look at that, I'm stripping away the R's in here. First of all, we want to catch the headers. I'm going to say that the headers are equal to the PeoplesVfilereadline. I'm reading the first line from my CSV file and then I am printing out the headers. There we go. Now if I write, Click and I run, look at that. I have my headers right here. Just for an extra thing, you'll notice that we have a space in here, we just do a strip and this should look good. Now we have the headers in a slightly better looking way. Now, the issue with this is if you notice on these tables, we can extract this information because we have them as roles, we have them as lists, we can extract the information. The only problem is that all of these values are strings, even the ones that are supposed to be integers, like the index, or that are supposed to be floats, like the salary. So that is obviously a problem. So now we're going to look at something called the quoting CSV files. You'll notice that I also have, you also have another file, It's the People's List CSV quoted. So I will copy this, I will paste it back in this file. Now in here we should see the quoted. If I double click and open it up, look at what we have in here. The quotation marks indicate that this should be a string, that this is a special something that should be a string, while the ones that are not quoted mean that they should not be strings. Anyways, let's see this in action and in real life. Now I'm going to create a new Python file. A new Python file that I'm going to call q CSV files did underscore CSV underscore files. In here I'm going to import CSV. I will say that the CSV underscore file name is equal to people quoted. People list CSV quoted with open CSV file name, new line, just an empty space or just nothing. I mean, people underscore CSV, underscore file. I will say that I have the reader which is equal to the V reader. People CSV file, and this is the most important one in here, I'm going to say. Equals to Sv non numeric and four row in reader print doesn't like the spaces here. Okay, let's right click, Let's run and we have a problem. Before I tell you what this problem is and how to handle it, first of all, we need to look at this argument right here. The quoting has been non numeric. This argument tells the reader to automatically convert all the fields that are not enclosed in to a float or an integer if possible. Now the error that we got is from this argument, because it's telling us that we tried to convert the ID, but we couldn't. Meaning the word ID right here, you'll see that ID is not in quotation mark. And the same will happen to the salary. For that reason, we have to do the same thing that we did before and that is take out the headers first. In here I'm going to say that we have headers equal to the people CSV file dot read line hoops, dot read, line, dot strip. And then I will print out headers, headers. And now we should not have any issues. As you can see, we don't, you'll see that we have the name ID, department, salary, job title, et cetera. In here we have the ID, but it's a float. Now the salary is a float. And that's great, that's perfect. But this should not be a float. We have to find a way to fix this by issuing you a challenge. Your challenge is making integers. So first of all, how would we go about fixing this problem, to think about it before moving on to the next steps? If you can think about it, you can do it. Go ahead and do it. I highly recommend that you do, but if you don't, this is your last chance to think about it. Here's a hint, convert every ID into an int using the int function before printing. But make sure you access the ID correctly from our roles, pass the video right now and go do the challenge. There's an extra challenge hidden deep inside of this challenge. Try to find it. Try to fix it. Welcome back. How did you get on with that? I hope it wasn't too hard. It shouldn't be too hard. All that we need to do is inside of this fore loop, I will take the row at position one because remember this is where we have it. And I'm going to say that it's equal to integer row one. And that's it. And now we can print it out in here. What's the issue? Unexpected type. And I think it's just not sure what's happening. Right click and run. Uh, what is the problem? A invalid literal. Everything worked except for what's the hidden issue here? Some of our ID's are not full. For example, after Mike Chen, if I opened this, let's look up two until we get to Mike Chen. Where's Mike Chen? Mike Chan is after David Lee. Sarah Kim. Okay, so my Chan, there we go, look at that. The ID in here is missing. So what we need to do before we convert all of these is we need to check if the row one is actually different than an empty string. If one is, excuse me, different than an empty string, only then will we convert it. And then we will print out the row. So and I right click and I run, look at that. We have everything printed out properly. Thank you so much for watching. I hope you understood what was happening. There's nothing too much in here. Nothing too complicated. In the next video, we're going to be looking at dialects and sniffers. Dialects and sniffers are going to be very important to be able to parse data because right now we know that we have commas, okay, in the case of the text documents, we knew that we have the certain limiters. But what if we can't see the file? What if it's hidden? What if we want to extract data from it and it's encoded in some way? How would we know we would need to use the dialect and the sniffer? And I will see you in the next video where we tackle these issues. I will see you then. 130. 10. Understanding Dialect and Sniffer: Welcome back my fellow Python developers. In this video, we're going to be understanding dialects and sniffers. Now, you might have noticed that every time we get information from a file, we need to know what that file or what the file that we're reading from looks like. Especially when we're working with TXT files. Does this file, let me show you what I mean. For example, right here, the TD for the Python poem. I mean, does it, how does it end? What does it have? What are the spaces in between it? Or when we try to parse, for example, to do the animals print on the people's list, x T, for example, we needed to know that we had this delimter right here. What if we don't have access to that file? What would we do? Well, we're going to use CSV in order to see how we can sniff through and understand what this file is made of in case we don't have access to it or maybe it's hidden or encoded, or top secret or whatever and you need to extract information from it. Let's go ahead and get started. We'll go to file new, create a new Python file that will call CSV underscore dialect. In here I'm going to import CSV and I'm going to create the people's file name equal to the people's list T. Let's say we have no idea what is happening in there. I will say with open the people's file name. New line because we're working with CSV even though it's a XD file, but we're working with a CSV file. And we'll say people underscore list here. I'm going to say that we have the reader. We always create a reader when working with CSV reader and the people's list. Then we'll say four lines in People reader, print the line. If I write click and I run, we should get all of the lines from that file. Notice that they are in the form of a list, but that is not a problem for us. The next thing we want to do is we want to see what are the separators inside of this file now. Okay, I know it's a pipeline, but imagine that we have no idea what these are. Also, keep in mind that each of these lines are a list that contains one item, which is not very helpful. So let's go ahead and start dissecting this. Let's say we know that it's a pipeline. If we add a delimitter in here, delimit, yes, this should be correct. There we go. And if we add the pipeline, if I write, Click and I run, look at that. We have dissected our lines. As you can see the problem is solved. But what if you wanted to create a code that can receive different types of Txt files that might have different delimeters? If the Demeter was for example. I don't know. Maybe you want this code to work on multiple files. Whatever type of file that you send it, it will limit it using its own delimter. The way we do this is going to be using the dialect and the sniffer. Sometimes CSV files or TXT files for that matter. Any type of files have different formatting options such as different delimeters, de characters or line endings, that is possible. Csv module provides two very useful tools which are the dialect and the sniffer dialect allows you to define the formatting option for a particular type of CSV file. The dialect is going to be the formatting, you know, when you have a language it always has its own dialect. How it's written, what are the rules for its writing, what is its grammar? The same holds true in cases where we have these different types of file formatting. And the sniffer works by analyzing a small sample emphasis on the word, small sample of the CSV file to determine the formatting option used. So the sniffer goes through a sample of the file, and I know I keep saying CSV file in here, but it's because the dialect and the sniffer work from CSV. But as you saw, we can apply TXT file to this as well. The sniffer goes through the file, sniffs around, sees what the dialect is, and gives it back to us so that we can then use it in the formatting and you can then pass the sample data to the sniffer sniff method, which will return the dialect object representing the detected formatting option. The dialect object representing the detected formatting option. You take a sample from the file, you send it to the sniffer sniff, it returns the dialect and then you can use that dialect in your programming or in your parsing or formatting or whatever enough theory. This is a bit complicated on the surface, but don't worry, it's very simple. Back in our code in here. Let's say we want to change a few things in here. First of all, we need to create a sample from that file. I will say sample equal to peoples list Read. Now you'll see that this is not something that we want but for now it will work. Then I will create the people dialect which will be equal to CSV sniffer sniff and I will send in the sample. Now if I write Click and I run, you'll see that I don't get anything at all even before using the dialect or testing things out. We don't get an output. And why is that? You should be familiar by now. Because we already read through the entire thing. Now the cursors again, imagine that you have this small robot cover going over every single character and line in that file. It's already read through it. What should we do in here? We should change this. Or at least we shouldn't change this, we should take it back to the top. And the way we do this is by using the people's list zero. Now this takes it back to the beginning. Before we continue on, we need to change this dilimeter in here to the dialect and say that it's equal to the people's dialect. If I write Click and I run, look at that, I get the separation without even knowing what we have inside. This is amazing, but there is a problem here that might not appear on the surface immediately. It's the fact that we are reading the entire file. And remember I told you that we need a small sample from this. Imagine if we have a file that's 10,000 or 1 million lines long and that could happen. Don't think it can't happen. You can encounter a lot of huge text files from databases or collecting data throughout years and years. So imagine you have to read through all of it. It will take a lot of processing power from your computer. So the better thing to do in here is to simply read through three lines. And that should be enough to get all of the information out. This is going to be a challenge for you to only read a few lines. First of all, instead of reading the entire file, read only a few lines from the file and use them as sample for the dialect. I'll give you a few hints if you don't want any of the hints. Positive video right now and go to the challenge. If not 321, create an empty sample string variable, create a loop over a certain range. At every iteration, a pen that sample variable with read line, pass the video right now and go do each challenge. Okay, welcome back. How did you get on with that in here in the sample? Instead of doing this like this or reading the entire file, I'm going to comment it out. I have an error, but that's okay. I'll say that sample is equal to just this empty string. I'll say four line in range. I don't know why I call it the line doesn't matter. It's because we're going line by line. I think it does make sense. Do sample plus equal peoples list. Read line. There we go. That should be enough. We are reading only three lines now. This should stay the same. Obviously nothing should change because in the first case, we were reading through the entire document. Now we're just reading through the first three lines. There we go. That is all we have for this. Before we move on, there are a few things that I would like to show you right here at the bottom. Let me add a print and let's print out a few elements that are available to us or a few properties from the dialect. The people's dialect that delimiter duplicate this, the people's dialect, The duplicate this. The quoting. If I write Click and I run, this is what we get. This is the delimiter. Look at how it was sniffed out. This is the, the character that we use for, if it was, for example, something different, maybe a single, we would have had that present to us as well. Then finally, zero means that we don't have any quoting in here. Let's test something else out. Let's test, instead of the people's list, let's test the people's List SV and see what we get. Keep those in mind. Right click, Run. All right, there we go. Now the delimiter is the comma, the quoting double quotation or the code chart is still double quotation marks and the quoting is zero. Let's test out the quoted. The people's list. People's list quoted. Let's see what we get. There we go. It stays the same. Nothing too much in here. Let's finally test out the Json file. What was the Json file called? J was this We could test out the Json test file, but I wanted to. What else? The students. All right, so the students let's test out the students. Jason, Run. All right. There we go. So you can see a few things are different in here. Don't worry about what we're reading. Obviously, this is not set up to read from Json file, but as you can see, there is no delimitter which is good. At least it's got that and there are a few code charts I'm quoting. Ladies and gentlemen, the dialect is very helpful when working with CSV files, JS files and TXT files in order to understand what is happening on the inside. If you don't have access to the file for some reason or you don't want to go sniffing through it yourself. Thanks so much for watching, I hope you enjoy it. At the next video, we will be writing CSV file, so I will see you then. 131. 11. Writing a CSV file: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at writing CSV files. Let's go ahead and get started. First of all, we're going to create a new Python file that will call writing underscore two, Underscore CSV and Enter obviously. First of all, we need to import CSV. That's obvious by now. The next thing is we need to get this data. Now I'm going to provide you this data somewhere, and as always if I do for some reason forget, please let me know in here. We're going to create an output file, we're going to have the output file name and it's going to be called people underscore written underscore v CSV. And then we'll say with open output file name comma because remember we're writing new line equals nothing in here as the output file, or let's call it out file just so we can have a clear distinction between the name and the out file. First of all, we need to create the writer object in CSV just like we have the reader object. We have the object, we'll say that the w is equal, is equal to sv. There we go. And then the file next, we want to actually write that data into the writer, we'll say writer right prose. The data, the data is what we have right here. Now if I right click and I run, you can see there's no output obviously. Let me right click and close other tabs. And then in here we should find that we have people written CSV. There we go, look at that. We have name, age, gender, country, city. And there we go, you can see we have John, Bob, Alice and so on. All three people, not too much, This is what we wanted. John Jane, we have everyone. John, Jane, Bob. Yes, we do have everyone in here. But sometimes the problem in here is that we don't have all of the data, meaning we don't have the headers for our data. For example, we would have this kind of data and we would have the headings underscore data like this or not even like this, maybe it's written like this. We have the headings on one side and we have the data for the people on the other side or in other list. How would we write the headers? Because now if I write click on, you'll see that in the people written CSV we don't have the headers. We don't know what's the name, what's the age, what's the gender. Obviously we do know. But imagine if we might not know. How would we solve this with a challenge? Write the headers into our CSV file. This should happen before we start writing all the other rows. And I will give you a hint in here, look for a function called right row. Pass the video right now and go do the challenge. Okay, welcome back. Just like we have read lines and we have read line which reads either a lot of lines when you use the red lines or one single line when you use the read line. The same principle holds true in here. You can write a row and you can write rows in here, right under the writer. I'm going to say right, right, oh my God. Right row and then the headings data, and then we write the data. So write the click and run, and if you look right here, look at that. We have the name, age, gender, country, city, and then we have the rest of the data. So ladies and gentlemen, this was very, very simple. We are almost at an end, but before we leave, there are two other methods that I want to show you that allow us to read and write from files much more easily. Or not much more easily, but maybe in a more sophisticated way. So thanks so much for watching. I hope you enjoy it and I will see you in the next video. Bye bye for now. 132. 12. Reading in a different way (DictReader): Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be looking at dict readers, so it will be a different way of reading from files. Let's go ahead and get started. First of all, the dictreader, it is used to read CSV files and parse the data into Python dictionaries. Immediately, we parse data into dictionaries. We've done this before, but in a much longer way. Now with the dict reader we have a much simpler way. A dictionary is created for each row in the CSV file, with the keys being the head er, row and the file, and the values being the corresponding values in that row. Dictreader objects can be used in a fore loop to iterate over each row in the CSV file. And dict reader can be used to read CSV files with different delimeters. Finally, dictreader is a convenient way to read CSV files into Python dictionaries, making it easy to manipulate and analyze the data using Python's built in dictionary methods. You have a CSV file, you have a lot of information. You use the dict reader to set it into dictionaries. And then you analyze and manipulate that data using the built in methods. Without any further ado, let's go back into our code and let's start coding. First of all, in here, I will create a new Python file that I will call the dict read, or let's just make the R capitalized CSV file. Hit Enter, and let's close all other tabs in here. First of all, import CSV. As always, we always say that it works on CSV, but this could work on other files as well. File name equal people's list, CSV with open file name, new line. And then as people file and we'll create the reader equals Csv, Reader, reader and people's file. Now when we try to, first we'll do four line in reader print line, right click run. And there we go. Notice how the output is in the form of a dictionary that we learned before. Now we're going to apply all of this to our people's text file and make a dictionary out of it. The keys are going to be the people's name, and the values are going to be the dictionaries from the read. Now before we do that, I want to also take you to parsing people, if you remember this file or project that we worked on. So in here we did basically the same. What we did is we parsed the file and created a dictionary ourselves. To help us look through it, we use two keys, the name of the person and the ID of that person, which we can then use down here to access their salary. So now we're going to do the same thing that we did in here, but in a few or a much less few lines. How do you say it? In a lines file? Let's create a new Python file. I'm going to call it dict, Read underscore people. Underscore xt. In here I will import CSV. I will create the people file name equal to people list of the XT equal to not parsing people equal to just an empty dictionary. Now I'm going to issue you a bit of a, your challenge is to use the, did open the file, use the dictreader in the file. What is missing in here, Add a second argument to the dicta function, which should be the liter is obviously the pipeline. No need to create or use the sniffer in here. We can just use the lime to do this fast. The main focus of this video is going to be the dict for now. Do the following challenge, okay, welcome back. Very simple, with open file name, come on new line. Obviously as people underscore file and then the dic underscore reader is equal to Sv dictreader, then people's file. Let's just try this. With nothing, I'll say four line in dictreader. Print line. Let's see what we get when I write, click and I run. This is the output as you can see. We have all of the headers being the keys and then the values are all of these things mushed up, so we need to use the limiter is equal to the pipeline. When we do this, we should see something a little bit different. So we have the ID one named John Doe. Department sales salary, 5,000 job title sales manager. Look how nice this is. Now we have separated these into dictionaries. Dictionaries have been created with the keys being the headers and the numbers or the values being each individual person with their corresponding ID, salary. You know what I mean? Before we move on, there's something we need to do. We want to start writing to our files using dict, right? To do this, we need to have a dictionary to write to that file. Let's go ahead and create our current code. I'm going to create a new Python file which is going to be called creating, underscore, underscore four, Underscore writing. You're going to see that this is going to be special. Honestly, I'm tired. I'm just going to copy this and put it in here. This one is going to be the People's CSV. For the CSV, also, we're going to have People's Dictionary. Actually, I'm going to have this exact same thing except four. I will have four line in the underscore reader, I will print out the line, but I will also do the following. Say that we have people line name case fold is equal to line, duplicate this and then the ID. What are we doing in here? Right click. And then I run. What do we have in here that case fold name. Wait, the limit. The read, okay. The limit in here is no longer the pipeline. Let's try to remove the limit. What do we get? All right, looks good to create the print and then print out the people. Let's see what we get. Right click and okay, something is not wrong. Built in method case full to STR, something is wrong. I mean, now we do have this dictionary, but it's not associating with the name. Excuse me, I apologize. Yes, there we go. So as you can see now we've parsed this data and look how many lines it took us. Look at the difference between this 16 lines with extra spaces. We could even reduce that. Look at parsing people, look how many lines it took us to do this. And look at how many lines it took us to do this using the dict read. So you can see that we have a lot of advantages when using dict read, but we haven't finished here. The next thing is to actually start writing to set file. First of all, we need to understand that we can actually open multiple files at the same time. In here, I'm going to open another file that we're going to be writing to. This is going to be the people underscore list. Underscore dict. Now this is a dot py file, and why are we doing that? At the end, it's going to make so much sense. This is going to be the output underscore file. First of all, we need to import CSV into our new dot py file, right? I'm going to print out import CSV file, file equals output file we're writing at the top. Let me show you. Right click and run. Let's look at the output, sorry, is that the people's list? Dictionary. People list, dictionary, list. There we go. Import CSV. Look, we are writing code without writing actual code. Next, we're going to print out file equals. Output file. Now what do you think this does? Very interesting. This actually creates an empty line of space. The next thing we'll do is we'll print out the following, people underscore table is equal to. We open up the parentheses output file, right click run, and look at what we get in here in the people's list dictionary. Next we're going to actually start writing things. And side, first of all, we need to determine the order of the headers that we have at the top right here, maybe just below the file name. I will say that the order underscore headers is equal to name ID, job title, come, and salary. Now I'm going to create a pattern. Now you might be very surprised at this pattern, but once I use it, it will also make sense zero through nine star back zero through nine. Basically, I'm going to add a comment in here, this will help us identify when we have a float number. Look at this, it says zero through 90 through nine with a.in the middle, or it might not have a dot. This is the pattern that will help us identify if we have a float number, for example. And we will be able to convert it then into an actual float instead of having strings. Now that we have that, next we need to do the following. After we do reader equals V dot read four line in the dict reader, we will not be printing the lines. Let's just remove these for now. The first thing we'll do is we'll create a new underscored dictin here. This is going to be just a temporary variable. Then we'll say four key in order headers, value equal to line at that key, we're getting the value, we're checking if the value is numeric. It's not allowing me to use the method on it because it's not sure if the value can even use the Is numeric, but the numeric should be there. If the value is numeric, we'll say value is equal to value LF bull. And I'll tell you this is going to look crazy. But R E match pattern come a value value equals float value. Let me just finish off and we will come back. Newt at the key case fold is equal to value. Then at the end we will print. Now we're printing to the output file. We are open this up, the back, the new dict, come on file, output file. And then at the end, once we're done, let me remove these, we don't need them. We will print out the closing brackets. File, output file, and then just an empty line of space. Let's write the click if we have any issues. The file, output file, IO operation closed up. I apologize. These two lines should be at the end. This is a very bad mistake on my part. Right click. There we go. If we look at the People's List dictionary, look at that. Look at what we've created. Now obviously there's still an issue in here. We need to add them. Because remember, this is where the new dictionaries are being written into the output file. Now if I write click and run again, we should have all of these look at that. The ID is an integer and the salary is a flawed. Let's go through this from the top to understand everything that is happening. First of all, we're opening the first file which is import file name, sorry, it's the People's list, CSV. We're importing the CSV file and we want to go into the people's table dictionary here. And you'll see in the next video we're going to be using this a lot with the dict writer. The next thing we're doing is we have this order of headers, correct? So we have the name ID, job title, and salary. We are going to be using these later on to create these lists. Right here we have the pattern as well. This pattern, as I said, will help us identify float numbers. And we've actually used it right here in this lip. We'll get this lip. We opened the first file. We open the second file, which we're going to be writing to, which is the people's list dictionary dot py. This is a py file. We print out, import CSV into the people's list dictionary right here. We write a small line of code or an empty line of space, which is right here. And then we print out people table with an open bracket, which is right here. Now we are going to get the dict reader. Create a dictionary reader. And we're going to go through every single line that we've read from the people's list CSV to see what we have on every line. We create a new dictionary, a new empty dictionary. We go through the keys in our order headers. Right here we use the key, we access the line. Correct. We've seen how line is accessed from running it previously. If you're still not sure, maybe what we can do is we can maybe print out the line again, just so you can see. Okay, so that we have everything in front of us. Let's say we're working with John Doe. Okay, we are at this line, we access the line. This is our line at the key. The key remember is going through the order headers. First of all, let's say it's name. We access the name. What do we have? We have John Doe. We check if John Doe, which is the value is numeric. If it's not, we check a Lyp. Is it a bull in here? The bull just like we have the integer which converts anything that you sent to it into an integer. The bull converts anything that you send into it into a bullion. It returns true or false. To check if the rematch, don't worry about this too much, just know that it allows you to match two things together. Try to apply the pattern at the start of the string to return a match of the object. We're, if this is not numeric then what is it? A float, for example. The way we're checking this is we're seeing if we have a number that goes 0-9 right here, zero to nine, right here, we have this match. If we have somewhere a floating point, it means that this is a float, which means we want to convert it to a float. I will add in here, this is used to check if we have a float using the pattern. Using the pattern, a good comment to that. After we do that, we create a new dictionary or we add to the new dictionary key case, fold value, and then we go back through this for loop. Again, we get the ID. Now on the ID we have a numeric string, which means we convert it into an integer. That's why in here we have this as an integer. Then we go through, again, the department sales. It's neither numeric nor does it match this pattern. It just gets added normally. Then we go to the salary. I mean, the department and the previous words I was saying, now we go to salary, we get the value we go through. Is it numeric? No, because remember we have a.in here. So we have some kind of character. Then we check if it matches this pattern. It does match this pattern. We convert it into a float, we put it back in the value, and this is what we get, the salary. And we also have the job title. We forgot to do that right here. Salary, job title. I apologize, and we're not getting it because job title. Oh, I'm so sorry for this. We already had job title, but for some reason I saw it at the end. It's being gathered right here. Sorry for that. As you can see, this is how it works. I tried to explain it as best as I could. If you're still unsure, please contact one of the instructors or me so that we can give you further help. This video has been too long. I think it's like around 22 minutes. I think it's a very long video. I do recommend that you watch it again. It's very, very helpful if you can understand this. I mean, I think the worst thing is this right here, the match. Don't let this throw you off guard. Make sure that you understand how we're creating a new dictionary and how we're writing it to the output file. And after we write all of these, look, we have the backslash D, which creates a tab. Then we close it off and we add an extra line so that, oh, you know what, maybe we don't even need the extra line in here because it's added automatically. Let's see. Yeah, there we go. So that we adhere to the Papa ladies and gentlemen, thank you so much for watching. We are almost at the end. In the next video, we're going to be looking at dictrter, which is going to complement this people's list dictionary. Thank you for watching, and I will see you in the next video, which will hopefully be not as long as this one. 133. 13. Writing in a different way (DictWriter): Welcome back my fellow Python programmers to a brand new video. And in this one we are going to be writing in different ways using the dictwriter. We started with this project in the previous video. In the previous long video. And in this one we're going to be continuing what we started. First of all, back in our file that we've just wrote our dictionary into, dict class is similar to the writer class that we've seen in the CSV module, but it also allows you to write data to CSV file directly from a list of dictionaries as we have right here. Which can be more convenient when you have data that is already organized in a dictionary. Let's go ahead and get started. First of all, at the top and here I'm going to add the fields. The fields that are going to be in that CSV file are going to be the name on the ID, on the job title, and the salary. They have to be exactly the same as the key names that we have in our people's table, In our dictionaries inside of the people's table. Next we're going to open up the file that we want to write the data to open. We've already seen this so many times. People, people data dot CSV to write and new line empty space as output. Underscore file two dots. We're going to create the writer, which will be the Svc writer, requires two things. First of all, it requires the object file or the output file that we are going to be writing to. And a list of the field names or the column headers, if you want to call them that, that correspond to the keys in the dictionary. In the list here, we'll have the field names equal to the fields. Basically what I mean in here. Let me open some ACSV file. It's these fields right here at the top. We need to provide it with those as well. That's why we created a list of fields. Next, we need to access the writer and write row, write headers or the header. We write the headers first. This method can be used to write the field names to the first row of the CSV file. And then we are going to do four row in people's table, two dots, right? Right. If I write click and I run, I don't get any errors. That's good. Let's look at the people's data, CSV, People data, CSV. There we go, Look at that. Ladies and gentlemen, we've created everything in here. Salary, job title, a name, ID, job title, and the salary. There we go, Name ID, job title and the salary for each and every person. This is one way of doing things. The other way is to use right rows right here. I'm going to comment this out and I will do, and I'm going to send in the people's table. If we click and I run, let's look at what I get. The same output. I set the names, and then I set every, There are two ways of writing this. Maybe you want more focus on each row. Maybe you want to change some things. You would use the for loop. If you don't, you just want to send in all of that data, you can just use the right role. Before we move on, let's say that we wanted to have our names sorted. You might think that it's as easy as saying sorted in here and then sending in the people's table, right clicking and running. But you'll see very fast that you cannot do this because you cannot compare two dictionaries. You cannot check if one dictionary is bigger or smaller than another dictionary. What we need to do is we need to actually compare the names of the people that are inside. To do that, we need to create a function that will do. For us, this is going to be part of your challenge and we are back to functions. First of all, create a function that takes a dictionary as a parameter. Very simple, it should return a string. These are indications that you should show the string it returns is the value in the name. Key access the dictionary, access the key name and return it as the return object from that function. Pause the video right now and go do the challenge. Okay, welcome back. So this should be pretty simple. I don't think it was hard back then. Where should we do this? I will do it under the import. I will say define underscore keys. Open this up and I am expecting act, which should be of type dictionary and it should return the SDR. These are the annotations that you should have added in here. You will return the dict to sort name. There we go. We add an extra space here and an extra space here. There we go. For example, in here, if I, for example, want to print out what was named sort keys, Keys. And it's not allowing me to do this. Let me write, click and do this. Okay. What do we have? The peoples table, for example. People table at the, at one, let's say. Right click, Run up. We're still comparing this. Let's remove the sorted from here. Try this again. All right. Jane Smith. Because at Jane Smith we simply return the name. You might think that it doesn't do anything. But what we can do in here is the following. We can say that key equal to the sort keys. Very interesting, but make sure to remove the parentheses from here around the sort keys because we're not actually calling this. If I write click and then if I go back to the people, you'll see that I have Bob because he starts with A B, Chris, with David, with the Emily, E, H, J, L, K, L, M and P. So they are all sorted just like magic. What did we do in here? If we hover over the sorted, we can see that we can provide it with something called a key. A custom key function can be supplied to customize the sort order, and the reverse flag can be used anyways, the reverse flag is just to reverse. But what we want to focus on, on this is this line right here in the documentation. A custom key function can be supplied. Basically, what we did in here is we did not call the sorting function or the sort keys function. We were providing the name of the function and the sorted will call it when it is needed. When you pass a function as a parameter to another function, you don't need to use parentheses after the function name because you're passing a reference to the function itself and not calling it. Makes sense. I hope that was understood. Basically, what's happening is the sorted is trying to sort the people's stable and it only uses the sort keys when needed. It goes, checks the name, comes back, then goes again, checks the name for the next people, and the next people, and the next people. Just as an extra thing in here, let's just create a new Python file, and we'll call this the function underscore argument, just so we can test it out. So I will define in here the underscore by underscore length. Let's say we're providing a word, not going to delve too deep. I simply will return the length of the word. Then in here I will say, we have a few words. Let's say the words. Let's say apple. Let's just pick fruits, banana, cherry, and the orange, orange. Let's say in here we want to have the words with an underscore equal to sort the words key, sort by length, okay? And then print sorted words, or actually will call the sorted words by length. This right here will be the sorted words by. Letters. And I will say that it's equal to words. Okay. This will help us understand what's happening in here. Let's add an extra space. When we do the normal sorting, we sort with the letters. Now, unfortunately, I made a, let's add. We'd, let's make the apples apples or like the apples to make it even longer. But now now apples, banana, apples. How many does it have? Three and then three. Okay, that's not good. Banana. Okay, cherries, orange. Actually, let's do banana apple, apple pies. Okay, So apple pies. So now if I write, click on, look at that. Apple pies is the longest word. Unfortunately, I made a very bad choice of words. In here, they are all the same length. Let's maybe remove the from oranges. And now you'll see that cherries is at the end. One, right here, we created this function that sorts or that returns the length. And we use that as a key to sort the words, not by their letters, notice, and here as a start, B, C, and maybe I should change the location of these, and this example is off the top of my head. So that's why I am not 100% sure of the word that we're using. Okay, What is the problem in here? There we go. Okay. On the first word, when we use the sorted without any keys, we are sorting by the letters. When we use the key, sort by length, we are sorting by the length of the word. Banana has six. Orange also has six, but for example, if I make this bananas, you can see that now orange is at the start. And then we have cherries and then bananas. Okay? And for example, if I add an extra R in here, there you go. You can see it's orange bananas, cherries. The key use in here by the sort, by length, Remember it's a function, but we're not using it as a function, we're using it as a parameter. But that's besides the point, the main focus here was using the right header. But we got, of course, but I still think it's very important that you these concepts. Thank you so much for watching. I hope you joined. In the next video, we'll be looking at how to use the dictwriter without a dictionary. And maybe we will be adding more lessons to the section. But I think for now that is enough. I think your head is probably about to explode because of all the information. But trust me, read through it, understand it. It's very simple, very easy once you use it once or twice. Thanks so much for watching and I will see you in the next video. 134. 14. How to use DictWriter without a Dictionary: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be using the dict writer without a dictionary. So first of all, we're going to create a new Python file. And the Python file is going to be the zipping underscore lists bo. The first thing we'll do is we're going to add this information into our file. Now, obviously I'm going to be providing you with this, but just in case you can't find it, let me know in any form of communication that you can get to me or the instructor. We could have easily added these CSV files and just be done with it. But we'll use this opportunity to transform them into dictionaries first and then use them in the dict rider. Now how are we going to create the connection between these two? We have movies, director and year. It's obvious that we have a list of couples in here and each couple contains three items, which are the movie director and the year it was made in. But how are we going to create this connection? How are we going to merge these two together? Well, we have a very useful object in Python that's called the zip object. The zip object is a special collection that is created by the zip function. Pretty obvious. The zip function takes one or more itterubles and constructs an iterator of tupples. It creates multiple tupples out of multiple itterubles. When we say itterbles, it means a list, a topple, or a dictionary, or a range, anything that you can iterate over. And then it constructs an iterator of tupples, meaning that you can iterate over multiple tuples. And we'll see what that means when we take a few examples where each tuple contains element elements from each itteruble. We said that we had two itterubles. These two itterubles are joined together to create iterator of tupples. And then this topple, or each tupple in that iterator contains elements from each of these two iterators. You're probably like, whoa, whoa. What the hell is even happening now? Don't worry. Once you see a few examples, it should become more obvious. The length of the zip object is the length of the shortest itterble. Because remember, we are constructing a third topple out of two itterbles. The shortest one will be the length of set topple. And finally, the zip object can be useful for tasks like iterating over multiple lists simultaneously pairing related data, like an hour example, or transposing data also like an hour example. So without any further ado, let's go back into our code and let's try zipping our two lists in here. I'm going to say four row in movies. I'm going through every single movie. I'm going to create the zip underscore object and I'll say that it's equal to zip keys row and if I truck keys to print out the zip object. When I write click and I run look at what I get, I just get a zip object, It's a reference to said zip object. It's not like actually printing out something useful. In order to see something useful, I'm actually going to just remove this because we don't need it. I just wanted to show you that it's the type of zip object. I'm going to instead do a four items in the zip object, print out the items. And let's just add a print in here just so we can separate these from each other. When I write, click and I run, this is what I get. I have movie the Godfather, Director Francis Ford Copolayear, 1972 movie, Pulp Fiction director Quentin Taro year 1994. Does this format remind you of anything? Doesn't it look like a key value pair? Basically, what's happening in here is we're taking the keys which are movie, director and year. So this is our first it, remember we said we had two itterbles. Then we are pairing it with another itterble, which is the row. And the row is changing for each movie, we pair movie with the Godfather Director, with Francis Ford Pla. And here with 1972. We go through this, we print out the items, boom, boom, boom. And this is why I told you that the zip object is an iterator of tupples because you can iterate over it, and at each iteration, you get a topple. That's why it's an iterator of topples. That's also why the length Where is it? The length of the zip object is the length of the shortest itterbal. Because if we had in here, for example, something else like for example, I don't know, actor right click and run, You'll see that the output is the same because there's no fourth element in here. There's nothing to join the actor with one of the elements inside of the stopple, we just take the shortest one, that's why it's the shortest. Now that you've understood how the zip object combines these two, how are we going to use this to our advantage? They do look like key value pairs, but how do we actually make them into key value pairs? Well, we've seen this before. What we can basically do, let's comment this out for now. Basically, what we can do in here is we can say movies underscore dict equal to dict zip object. We convert the zip objects into dictionaries and if I print out the movies dict at every iteration, we should get the following. Look at that. Now we have a conversion. We have literal key value pairs with the director and the year and the movie name. Now that we have our dictionaries, it's time to use the dictwriter. When I say it's time to use the dict writer, I mean it's time for you to do a challenge to write dict writer. First of all, we need to obviously import the CSV module, open the file, we want to write two with the correct mode. You can name the file whatever you want. Create the writer object using the dict writer, write the headers, don't forget the headers. And then add the code we did earlier inside the with block of code. When I say when we say with open et cetera, the code that I'm talking about is the code that we just created here. This code, this should be inside of the width. It should be pretty obvious. But just in case, right, the dictionaries created to the CSV file with the right row. Pass the video right now and go to the challenge. Welcome back. How did you get on with that? First of all, as we said, we need to import CSV. Great. The next thing we need to do is we need to create the file name. In here we'll have the file name equal to movies zip sv. Next, we need to open the file with open file name, that is the correct mode and the new line, nothing as the movies underscore CSV or movies zipped underscore CSV, that's a very long name, that's very unnecessary. I'm going to make this a bit smaller, push this to the front and we'll say that the writer is equal to Sv dict writer and we are going to be writing to the movies zipped underscore CSV with the field names being equal to the keys. We've already seen this before. Then with the writer right headers, we will go four row in movies, et cetera, et cetera. And then what do we do at the end after we print out the movies dictionary? We don't even need to do that. We'll say that the writer right row the movie dictionary. There we go. When we run this, we should see that a new file was created right here in the project, which was the movie zipped. If we open it up, look at what we get. Nice. The headers are in place. Movie director, year, the movies are in place. Everything looks good. Ladies and gentlemen, thank you so much for making it this far in the videos. Thank you so much for making it this far. And of course you are part of the two M Python master class. I mean, if you've gotten to this point, you basically have more knowledge in Python than 99.7% of the human population on Earth. And I congratulate you already with your amazing skills. You can start applying to jobs, you can start looking for deeper information. But I think that you still need the extra information that is going to be coming up in the next section, which is Database SQL. It's very important. This is probably the last video. I might update this later on to make it more extensive, but for now, this is the end. Thank you so much for watching. I appreciate you being here. If you can leave me a review anywhere, please do. Let me know what you think and I will see you in the next section or video. 135. Section 10: Using Database in Python | : Welcome back my fellow Python programmers to a brand new video. And in this one, oh, and a brand new section. Of course, in this one or in this section we're going to be looking at using databases and Python and SQL language. So this video is going to be database 11, where we will just be understanding some terminology, what database is, how it works, what can we do. And then we will install SQL Lite three. We'll also explain what SQL Lite Three is going to be. We will set things up and just make sure that we can confirm or continue on from there. First of all, what is database? A database is a structured collection of data. We've already seen a lot of structured collection of datas like couples lists, dictionaries, and sets. All of these are also structured collections of data. But database comes in handy when we start having huge amounts of data. It is organized and stored for easy retrieval, manipulation, and management. So just like we have with list stupples, et cetera, et cetera, we also have the same idea behind databases. If we have a lot of data like e mails, names, locations, whatever, we want to set them in a structured manner so that we can then later retrieve them when needed, change them up, manipulate them and manage them, make sure that they are well organized. It's designed to efficiently, efficiently store and manage large volumes of data. Store and manage is the key word here. Large volumes of data is also very important. You get to a certain point where saving the data to a list is not feasible anymore. Setting it up in, I don't know, maybe Json file is not feasible enough. You need a database, you have millions and millions of people. You have thousands of gigabytes that you need to save. Files are no longer good, You require database allows users to store, retrieve, update, and delete information. Databases are widely used in various applications such as website, enterprise systems, mobile apps, and many more. For example, when you're using Facebook, when you're using Instagram, when you're using Google, when you're using any website, any website that you can think of, any application that you open that you can think of uses a database. Database is super, super important. This is one of the advanced sections. But if you want to go into any career, almost any, if you're looking to become a data analyst, data scientist, if you're looking to do machine learning in Python, database SQL is important, super important. Let's take an example of a database so we can see what it is. To be fair with you, a database is just a very glorified table. Of course, there are many more intricacies to it. It's a collection of very advanced and well organized tables. But if you look at it, it's just a table. First of all, it's the table. It's the collection or a collection of related data organized in rows and columns. Then we have the fields. A field is a single piece of data within that table. Sometimes it's referred to as an attribute, sometimes it's referred to as a data value. You'll find a lot of different nomoclatureor terminologies for these things. Just try to follow the ones that I provide you with. Maybe if you go looking around on the Internet, you'll find different terminologies. For now, I would follow these. Next we have the columns. So as you can see, it's a vertical arrangement of fields within a table. So for example, the customer IDs are all arranged in a column. The last name, last names are all arranged in a column. The phone numbers, the countries, and then finally we have the row. So it's a horizontal arrangement of data within a table, also known as a record or a couple. You'll see both of these words used. We're going to be referring to them as rows as often as possible. This is an example of a database, It's just a glorified table. You'll see there will be more intricacies to this later on. What is SQL and what is SQL? Light SQL stands for Structured Query Language. It provides a set of commands and syntaxes to interact with databases and perform operations. Just like you have Python language, which allows you to interact with the processor of your computer, which you send it some commands. In English, it returns some output. The same is true with the SQL. It's a language that allows you to talk to databases. These operations are selecting, inserting, updating, and deleting data. We will be looking at all of the operations in SQL. Query is the request for data or information from a database. Maybe the only weird word here was query. The query is the request for data or for information from the database. Now what is SQL light? It's a lightweight version of SQL which is server less and self contained. When you're working with databases, you're usually working with servers. Servers are just, you can imagine them as a big, had a huge hard hard drive with millions of gigabytes that are available to you where you save information. When you're working with Facebook or any website or application that you're working on, it's usually you as the client or as the user contacting the server through SQL language and retrieving data from there. Now what we want to do is we want to use SQ alight, which is server list, because we don't want to go through the hassle of getting servers and trying to test things out on there. We'll do it server list using SQ alight, meaning on our computer, so the databases will not be saved to some server on the outside of our computer. It will be on your desktop or your PC or whatever, and we'll do it using SQ alight. Don't worry. The same commands hold true. It supports the full SQL language, so when we work on SQ alight, it's the same as working with SQL language. It's used in applications that require local database like us. Or for example, if you have a small application that saves some file on the user's cell phone, then SQ Alt is the way to go. Without any further ado, let's go ahead and get started. The first thing we need to do is we need to go to this website right here, which is Sqlite.org in here. Just go to the downloads, of course. I will be providing you with the link once you go to the downloads. And here you need to pick either the Linux, if you're using a Linux, the Macos, or Windows, you need to select this. A bundle of command line tools for managing SQL database, et cetera, et cetera. Either this one or this one, or this one right here. Select one of these. Download the file. As you can see, it's a very small file. Now, it's very important that you do the following. You take the directory, you take the file and you need to put it in one of the directories, meaning either the D or or somewhere else. And it needs to look exactly like this. Look at this SQL tools, Do whatever the name of your file is. It doesn't have to have the same name. As long as when you open it, you have these three folders inside. This is very crucial to follow. You have these three folders. It's in the local disc D directory. You can see the folder right here. When we double click on the folder, we have to see these three folders inside. Okay? Clear on that. Good. Once you have this, the next step is also very crucial. First of all, I want you to go to control panel. When you open it, I want you to go to system and security. Now maybe yours is a bit different. I will set the steps somewhere below the video. If you forgot the steps or you can't follow them, please contact me or your instructor and they will help you. Once we have the system and security in here, we need to go to system from system, you need to go to Advanced System Settings. It should be around, maybe your version of Windows is older or newer. Go to Advanced System Settings. Once this is opened right here, I want you to go to environment variables. Now we have two things to do. We can either or one of the two options. You'll see right here, we have user variables for ish. Now ish is the name of my Windows. Unfortunately, when I bought this laptop and I changed the names, I didn't set it correctly. Now, I'm stuck with this curse, but that's okay. No problem. You should find the path here. If you don't have the path, you need to create a new use variable. When you click on the path, you need to go to Edit. Inside of the edit, you'll see many options in here, but one of them should be this right here. This is the path of the folder that we just set up in the directory. If you don't know what the path is, go back into your directory, open this file, select any of these three folders, right click property and copy the location. Copy it, control C, You don't want to type it out. Just copy it out, right? Control C, Go back in here, add a new right here, and just paste it. Okay. And that should be good. I will cancel because I don't need to do this just in case because I've had some students that don't have the step work for them. You can also go into the system variables, go into path, go into edit, and add it right here. Please do not delete anything from this. Don't delete anything from this part either. Keep it exactly as it is and just add the SQL tools. And you should be good to go if you follow the steps correctly. The most important part is making sure that this folder right here is the exact same scale light tools, not as mine as yours. When you extract the folder and everything, when you open the folder, you should see these three folders or files, or applications wherever you should see them in here. Then when you go to control panel, system and security system advanced system settings, environmental variables right here. Copy the path. Where is it? Right here. Use variables, path, edit, or new. If you don't have one edit, send in the path of the folder of the applications. If that doesn't work, you can also add it to the path right here. But I don't think it's necessary. For example, on my side, it was not necessary. On one of my students, it was necessary, test it out, see what works. Hopefully it does. And if you don't find it, contact one of your local instructors, of course, from two empt on De. Now, with that out of the way, we want to test out our SQL connection. So it's going to be a challenge for you. Open the command prompt. If you don't know what the command prompt is right here, type in command prompt book and you should see the following with your PC name instead of mine. Type in Q three, it's right here, just as it is right here. It should have a version displayed, type Inq. Now we are ready to work. Posit the video right now and go do the challenge. Okay, welcome back. How did you get on with that in here? Ask lid three, hit enter, and you should see something similar to this. You don't, if it's telling you there's something missing or this is not available, go back, do the steps again. And if you still can't figure it out, contact me. Contact the instructor that's assigned to you and that is it. Thanks so much for watching. I hope you enjoyed it. I hope you're ready for this journey. Sql database is very easy when you go through it step by step and understand everything that is happening. Don't be afraid. Even though this might seem as a new language, it's fairly, fairly easy. If you've done all the sections in Python so far, this should be a cake walk or a piece of cake? Or a cake walk. Do they say cake walk? I'm not sure. But anyways, thanks so much for watching. By the way, we'll be working in the command prompt for the next couple of videos until we learn and comprehend SQL correctly, then we will move on to using the Intelligent and Python. Okay, thanks so much for watching. I will see you in the next video. 136. 2. SQLite 101 : Welcome back my favorite python programmers to a brand new video. And this one will be delving into Skylite 11 or Esculte three or whatever you want to call it. First of all, as we've seen before, we need to open skylite three. But this time we actually want to create a database. I'm going to type in light three space test B and a Sem column. Hit enter and you'll see that testdb was indeed created or opened. Sometimes it's opened. Now if we go right here, let me show you where this is actually created. So if you go to see users and then the name of whatever, you'll see that the Testdb or Testdb was created right here. As you can see, I have this one. What I'll do actually, is I'm going to delete it because this was from previous students. I will delete this. Okay? It's not allowing me because the file is in use. Very nice. What I'll do in here is I'll do quit and this is going to be very important. That's why I will keep it in the video. I will delete this one as well as you can see now I can do esculte three space test B semicolon, hit enter, and we shall see that. Let's go back. Where is it? Why hasn't it been created? Where is my database? It should appear. Okay. It's not appearing, It's okay. We will look at it later on. For now, let's start with escult three. First of all, let's do the help. Help shows us a lot of useful information that we can or we will actually be using later on. Some of the useful information we've already used like the Quit for example, which stops interpreting input streams and exits. If whatever the recovery is going to be important, the restore the schema or schema. In French, we pronounce it schema, schema. You will find also something very important, the header. Where is it? The headers will be in use? Those are a few things. First of all, in here, I will do the headers space on which will turn on any headers that we have in the table. Now it's actually time to create the table. I'm going to create table contacts. And the table name is going to be contacts. And inside I will have the name which is of type text, the phone which is of type integer, then the e mail which is going to be of type text. Whenever we do a line or command language, we have to finish with a semicolon. When we hit Enter, the table is indeed created. Now maybe we'll see the test DB. There we go. I think it was, oh, by the way, I apologize. We didn't have to use a semicolon. Right here, right here when we're doing the SQL three. When we're doing SQL commands like table contacts, we need to add a semicolon when we're doing just prompt commands like the Sqlite three test B, we don't need to use a semicolon. It's just a force of habit. Like for example in here on the dot headers on, we didn't need to do a semicolon, I apologize, it was a force of habit, but it's good seeing like you, seeing the mistakes that I make from time to time is very important. But anyways, and here we've created a table in our database. Now you'll be like, okay, where is this table? Well, if we look right here in our Helps, maybe we could find something useful like for example dot ABC, RST do tables nine. So list names of tables matching like pattern. Don't worry, let's just do tables and there we go. It gives us all of the tables that we have and one of them is contacts. Very nice. Now let's try to insert some information into the table. I'm going to type in Insert into contacts, into the name, into the phone, and into the e mail. And I'm going to say that the values are going to be, and we don't need to add a space, but we'll add it anyway. And by the way, make sure you understand how dis cursor works. The name will be Michael. It should be in between single quotation marks. The number is going to be 1,589.365 And I just made it up, by the way. Please don't call this number, then the E mail is going to be contact at two M. Python dev.com Very nice. When we don't hit Enter. Oh, actually let me show you what happens if we hit Enter on a command that is not complete. Look at that. It opens a second line. It doesn't execute when it executes. You'll see it right here. You'll see it just prints out as a light. But it did not finish executing. So we can add this extra semiclumnow executes, all of these follow. So what did we do in here? We insert it into. So these are the commands insert Into. Into, into contacts. What do we want to insert? The name, the phone, and the e mail. What are the values, Michael, this number, and contact at 02:00 A.M. Pythondev.com As you can see, the only issue in here is that if we did get an error, it does not show us how to fix it. But this is why we're using. The command prompt is going to help us increase our SQL skills substantially from just using the normal IDE for this. Because either way, there are very few ID's and languages that really give you any hints of how SQL works or where the exact error is. Getting to know SQL through the command prompt with almost no help, is going to be very helpful for us. Now, by the way, I might have lied. You can actually use the double quotations. Let's say I want to insert another value instead of selecting all of this and copying it, which I'm not even sure works. And if you hit control C, you have to right click in order to paste it. The control V works as well. But that's besides the point, let me remove it. There is an easier way of doing this. So let's say you want to go into a previous command that you had. You can use the arrow keys. So if I hit up, look at that. I get into the command key that I had used and now I can add a semicolon. Let's try the double quotation marks around contact. And Michael, let me change this actually changes to Steve. Sure, Steve, let's change the number and we'll change their E mail to Steve. At Steve.com There we go. No such column as. Okay, there we go. That's I think only using a single quotation marks. Let's test it out. There we go. Exactly. So it is very nice we're exploring together. We're testing out things together. It's very important we've inserted another piece of information. Now how can we display this information? Well, we can type in the following. Select star from contacts. Star means that we are selecting everything. If I hit Enter, look at that. We have the headers if we haven't typed in the head, if you didn't do it, you'll notice that you don't have the headers. But because we typed in headers on, we have the headers and these are our information. You'll see that they're separated by this delimeter which is the pipeline character. Now as you can see, we've inserted this information, but this is not really how we write SQL language. Some people write SQL this way. But this is not the conventional way. The more conventional way is setting the actual SQL commands as capital. For example, select star from contacts. The QL commands here are the select and from the insert into. These are the things that don't change and the values, these are the words, the commands that don't change. These are the actual L commands, they don't change. But for example, the name of the table could change the name of the values that we want to insert. Could change these stay in the lower case. Like for example, contacts. Because we are from the contact table, we might want to change this to another table. Now, what is the star in here? The star means we are selecting everything. The name, the phone, the e mail, and everything that's available to us. But what if, for example, we just wanted to select the names, Then we would select name. Name. Because keep in mind it's the same word that it's right here. So if we type in names, for example, it will not work. Select name from contacts. Hit Enter, and look at that, we just get the name. Very nice. Now, let's go back into inserting. I will use the arrow up key in here. Actually, we should start changing. If you know what, let's just delete all of this. We don't want it. We will start from scratch because we will use insert into, what are we inserting into the contacts table. And now usually in here we should do name, phone, e mail, and then provide the values. But if you have all the values in place, for example values, I can now provide it with kalen. The number is 123-45-6789 and we'll see that it's Kalen at kalen.com semiclumn. Insert into values are the actual SQL language key commands. I mean, then you have the contacts table and so on and so forth. So that's why we have them in upper cases and lower cases. Notice in here because we've provided the name, the phone, and the e mail, or all correctly, we don't need to tell it to which fields we want to be added or to which roles we want these to be added. It will be added automatically to the appropriate roles. Now if we hit Enter, you can see that it worked because we don't have an extra line. We just have scar line command without any errors or warnings. Now if I hit the arrow, keys select and we'll do star from contacts. Look at that. We've inserted kalen into our database. Okay. Now the issue in here is what would happen if we tried to insert into contacts? Let's now try to do, Bob, let's say for some reason we just forget the e mail. Forget the number. Just forget the number by mistake. Hit Enter. Oh, there is an error parse error table. Contacts has three columns, but two values were supplied. So how do we fix this issue? Well, we provide you with a challenge. Add the contact anyway, find a way to add the person into the database. Anyway, I will give you a hint if you want, you can go search for this yourself. This is a great journey to start on your own. But the hints are specify which attributes you're adding, similar to what we did before. And when I say what we did before, I mean right here. So for example, you are providing the name and the e mail specified that you are providing the name and the e mail. So pass the video right now and go do the challenge. Welcome back in here we're trying to provide, Bob. So if we go up right here, you can see that we're only providing the name and the e mail. So I will say name, come on e mail book and now select star from contacts. There we go, you can see that Bob does not have a number, and he's also in the lower case, which doesn't look good. But we will see in the next video how we can update, delete, and also use the War in SQL. Ladies and gentlemen, thank you so much for watching. I hope you enjoyed. Some of you might be scared, some of you might be excited. But please don't worry. That is the most important thing. We will go through these step by step. If you're not sure what we did right now, please go back. Understand every single small detail that we did. These are going to become very trivial, very easy as we progress through the section. And I will see you in the next video. Bye bye for now. 137. 3. UPDATE, DELETE and WHERE: Welcome back my fellow Python programmers to a brand new video. In this one, we're going to be looking at update, delete, and where, meaning more SQL using SQL light. First of all, we're going to quit. When we quit, we simply close down the database. Let's go ahead and clear all of these lines so we can type in CLS. If you're using a Mac, I think you can type in Clear. Hit Enter and it should be cleared again. Let's open up Sqlite three, test B semicolumn. Unfortunately, I've called it like that. I have to type it in again to open it again. If you've called it something else, then please do type in something else. Next we're going to hit Select Star from contact semicolon. Hit Enter. There we go. These are all of our contacts. Next we're going to insert into contact. Then values. And the values are going to be, James must have an upper case, the number should be, there we go. And then we will have James at.com And I'm using James.com and everyone by their name or the website with their name on it because I don't want to sponsor anyone. And we have a problem. Because look at that, this is a very good issue that we just encountered. No such table as contact, because the table is contact with an S. So there we go. It's very crucial that you always have everything set up correctly. The next thing we want to do is we want to create a backup for our database, because now we're going to start deleting and adding things. So we want to make sure that we always have a backup for our database just in case we mess things up in here. It's very simple, just hit back up and then call this the test underscore backup. Boom. Hit enter. Now, if we go back in here, as you can see we have test underscore backup, which is our backup. Also something very important that we just glanced over right here. When we selected star from contacts, we did not get the headers. Why is that? Because we started where we opened the database from scratch. We need to say headers on, and then select star from contacts. There we go. Next I want to update one of our e mails. Let's say Kalen got a new e mail, I want to update it. I'm going to do update contact set. These are the important keywords, update and set. Email equals underscore kal calen.com and then semicolon. Hit Enter, select star from contact. Oh my God. Oh no. Oh, no. Look at what just happened. We just changed all the e mails of all of the contacts that we had. That is a huge problem. We've destroyed our database. Somebody trusted us with this database and we destroyed it. But thankfully, we did something very important that Michael told us about, which is to back up and how do we restore our backup. We restore test. Underscore back up. Boom. Select star from contacts. That's good. We were almost fired from our job, but thankfully, we were able to watch Michael's course and now we are no longer fired. Very good. Next thing we need to actually update only where we have Kalen. How do we do that? Well, we do the update again, but now we don't stop here. We actually where name is equal to Ken. And keep in mind it's case sensitive. Now if we enter and we select Star, there we go. You can see that only Kalen had their E mail updated to new Kalen at Kalen.com There we go. This is the update. Now it's time for a bit of a challenge. And your challenge is going to select only Steve. I want you to select from contexts where name is equal to Steve Google It, and try to find the solution. Otherwise, here's a hint, if you want, you can positive video right now, go do the search on yourself. Or maybe you already know the solution without any Google search. But the hint is to use where name equals Steve. Select from contexts where name is equal to Steve. Positive video right now and go to the challenge. Okay, welcome back. How did you get on with that? In here I'm going to select Star because I want to get everything from texts where the name is equal to Steve and Sem Nicolo. Now if I hit Enter, boom, there we go. That I only get Steve and not everyone else in here. We could do something else, for example, we can not star. But let's say I want to select only the phone and the E mail from contacts where name is equal to Michael. All right, this is Michael's number and that's his contact e mail. We can also use delete and we should also be super careful when doing this because like the update, we can potentially delete everything in here. When we want to delete, I can say delete from contacts where name is equal to Bob. Because if you remember, Bob doesn't look really good. They're missing an E mail, the written in the lower case. We want to get rid of that data. Hit Enter and now select Star from Contacts. There we go. We don't have Bob anymore. Keep in mind if you do delete from contacts, you'll keep that in mind. And by the way, something that we did not mention or maybe something you might not be clear to you. When we do delete from contacts where name or when we do select from contacts were name, we don't just have to provide the name. We can say for example where number or when where foam is equal to. Let's say let's delete James. I will just copy James number. James number and then click. Did that work? Nope, it did not. Let me try this again. Control C, will it work? Right, There we go. Boom. Select Star from contacts. And there we go, you can see that James was deleted isn't just with the name, it could be used with any of our headers. Right here. Right here. Okay. So before we leave, one more thing I want to do is I want to try and insert. Let me just find it. Insert into contacts. James, I want to try to insert. Instead of a number, I want to try to add a number in the form of a string. Because I want to do this plus 15. Obviously this is not an integer because we have pluses. But remember, we said that we wanted the phone to be an integer. So let's see what would happen if we do the following. If I had Enter, it works. We added it even though it's not an integer, it's say string, and it worked. If we try to select star from contacts, look at that, we actually have the number. Now on the surface, you might look and be like, okay, this is no problem. But if you start working and interacting with this database more and more, this can cause huge problems. We need to always make sure that we add things properly. We don't want to have issues like these. If we said that the phone is an integer, it should stay an integer. And you need to make sure through your user interface that this is the case. So I'm going to delete from contacts where phone, where name is James, because this is not good. Bye bye James. Select star from contacts. All right. This is the basics of it. The last thing I want to do is I want to go over a few, a few commands that we can do in the SQL. For example, tables. This command displays all of the tables that we have in our current database, we have the schema. This is a very important one because this command is used to display the schema or of a specified table, or all the tables in the database. The schema represents the structure of the table, including the columns names, da, data types, constraints and indexes. For example, if you're trying to select only a few columns, but you don't know what D's are, you can use the schema to find out how the table was created and what values or what headers you can insert into or what roles you can insert into. The other thing is the dump them. This command is used to generate a text file containing the SQL statements that can recreate a database scheme from scratch. It outputs all the SQL commands necessary to recreate the database and its contents. For example, first of all, we ignore these for now. Later on we will explain them in more depth. But for now, look at the Create table and the insert values so that we can recreate this exact database. Notice that we didn't provide or the dot did not provide us with the deletes and the updates and so on and so forth. It's just if you want to recreate your current SQL database as it is, you can use this text file. And notice at the end we have commit, something to keep in mind for later on when we start working in Python. And finally, we have the exit which is similar to the Quit. This command is simply used to quit out of the SQL light command line interface. Ladies and gentlemen, thank you so much for watching. I hope you enjoyed. I hope you're not too confused. In the next video, we're going to be looking at database administration, where we will be querying data with our SQL light. And we'll be using a much more extensive database that I will of course, provide you with in the resources. So thank you so much for watching. I hope you enjoyed leave me a review anywhere that you can contact me if you ever have any questions. And I will see you in the next video. By by far now. 138. 4. Database Administration: Welcome back my favorite Python programmers to a brand new video. And this one will be actually going through an actual database that I've provided you with. Below this video, there will be a link or a button or something where you can download movies B, which is a database of movies. The first thing we want to do is we want to right click on our desktop and create a new folder, and we'll call it the movie Database, okay? And we're going to put the movies into the movies database. So we have something like this from here. I want you to right click and I want you to go to properties, and I want you to copy this exact location as it is control C. And hit okay. And now back in the command prompt, I'm going to do CLS to clear everything and I'm going to do CD. And then right click to pass this. And when I hit Enter, look at what we open now. We're no longer in C, users ish or whatever the name of your computer is. We are now in the users is desktop and the movie database that we just created because now we want to open the movies B. If we don't specify where this movie dob file is, it will not be able to find it on its own. In here I will type in Sqlite three and then movies B and hit Enter and we are on. Let's go ahead and first of all set the headers on headers on Enter. Now how do we know what tables we have? Tables, boom. Hit Enter, we have three tables, we have actors, genres, and movies. Let's go ahead and let's go ahead and actually select star from the movies. Let's select everything in the movies. And there we go. As you can see, we have the Shaw, Shank Redemption, Godfather, Dark Night, Pulp Fiction. And in total, we have ten very nice movies that I've selected. So you'll notice that first of all, we have the movie ID, and then the title, and so on and so forth. Now I have a bit of a challenge for you, and your challenge is to show me the headers. Now, sometimes I forget what the challenges are. So one of the challenges was to turn the headers on. This was an easy one, but now I want you to select from the movie table, the movie title that has a movie ID of three. Now keep in mind what did I ask in here? I want you to select from the movies, the movie title that has the movie de of three on the movie title. I don't want everything on the movie title where the movie idea is three. Pause the video right now and go do the challenge. Okay, welcome back. How did you get on with that? So we said we only wanted the title and look right here, we have this title. So I'm going to select title from movies where movie ID is equal to three. Hit Enter and it's the dark night, very nice as you can see. We have a database that now we can administer and we're obviously going to be looking a lot deeper into this database. But for now the first thing we need to do is to create a backup. And the backup is going to be movies underscore, back up one, Let's call it back up one because I have a feeling that we will need to create multiple backups back up one. Now if we open the movie's database folder, you'll see that this is where the movie backup was created. Very nice. Now let's go ahead and look at other tables. Let's go ahead and Genres. We'll select everything from genres. Yep, that's how it's written. Boom Head enter. No such table as genres because this is case sensitive and I've already told you, and sometimes. Okay. It's still not a select star from Jeans. Okay. Okay, Let's test out if it's actually no. Okay. And in here we have an E, hopefully. Yes. There we go. So the table name and the column name are not actually case sensitive. It's obvious because right here we did movie ID with a lower case M, and here we had a upper case M. But for example, if you want to select 12 angry men, this would be case sensitive. So just keep that in mind. Now if we look at our genre, you can see that we have the genre ID and the genre name and we have drama, crime, action, and adventure. Very nice. Let's try to insert into this database. I'm going to insert into values. Values are going to be, well, first of all, we need to provide the ID. The ID will be four. I will do comedy. Now, obviously you're telling me right now, whoa, wait, why four? We already have a four. What's the issue here? I just want to show you something. If you'll see that I get an error and it's very important that we read what this error is. So you'll see parse error near inserts and tax error. But what really is it? The error is that we typed in instead of insert. And I don't know what the matter is in the matter with me today not typing correctly. The words are not coming out as you can see, but we'll try to get through it. Runtime error, unique constraint failed, and the genres, genre, ID. There is a problem in here. Basically what it's telling us is that you cannot have keys that are not unique. But why is that? Let's do the schema and look at how this table was created. So you'll see that we create the table, movies, table genres and table actors. And you'll see right here that we have the movie ID, which is an integer and it's a primary key and it auto increments and that holds true for our three tables. Right here we have the actor ID, it's an integer and it's a primary key. And when we say a primary key, it means that you cannot have the same key appear twice, meaning like four adventure. You cannot have four comedy. Also, something very important about the primary key in here is that it auto increments and we'll see how that works later on. Another thing that we also should keep in mind is the null, meaning that we cannot have empty fields. If we try to add a movie, we have to provide it with the movie ID and the title and the release here. And the genre and the director and rating obviously because they cannot be null. Okay, I hope that's clear. There's nothing too much in here. The main important thing is that we have a primary key. Primary key means it cannot be duplicated. Just like we have a set, for example, a auto increments. It increments on its own, and I'll show you how that works. And we also have something called a foreign key, but we'll look at that more later on. For now, if we want to insert something into genres, we have to do the following. Insert into genre's value. And now instead of comedy or four comedy, I can just do comedy like this. And instead I'll just have in here documentary. Okay, hit enter. Look at that parse error table. Genre has two columns, but one value was supplied. How do we solve this issue? You should know this by now. Exactly. I can hear you say that. So the genre Name and make sure that it's correct. Name, Genre name, hit Enter, and there we go. Now if we select start from Res, there we go. You can see that the ID auto incremented and we have the documentary at the bottom. Thanks so much for watching. I hope you enjoyed now getting into the administration of an actual database. I will see you in the next video where we will be working on order by and joining tables using the foreign keys that we looked up right here. Before I go, just to show you, we have the movie ID, title, release, genre, ID, director, and rating. You'll see for example, the Shashank Redemption release year 1994, and the genre ID is one. And if we go back into our genres, you can see that one is drama, because the Godfather, or the Shawshank Redemption, is a drama. If we look, for example, Pulp Fiction, the genre idea is four. If we scroll down, we'll see that four is adventure. We're going to see how we can connect these two keys. How we can create a connection between the genre table and the movie table. Thank you so much for watching and I will see you in the next video. Bye bye for now. 139. 5. ORDER BY and JOIN our Tables: Welcome back my favorite python developers to a brand new video. And in this one we're going to be looking at two things. First of all, we're going to be creating the connection between the genre ID on the movies and the genre ID in the actual genre stable. So this is going to be the joint part. But before we do that, we need to look at order by. So for example, right now if I select from genres, you'll see that we get them in the order of the genre ID. But that's just because this is the default and we don't have to adhere to any default settings. So we can specify that we want to order them by the genre name. Now if I hit Enter, you'll see that they are ordered by their genre name. Well, it should be pretty obvious there's nothing much to it. We start with action than adventure, because we start with the first letter and then we go to the second letter, A, B, C, D. Then see drama. But not something. Documentary is at the end. And you might be thinking, well, that's maybe obvious since drama and documentary and that's the end. Let's try to insert into genres, genre name, values, and then we will do comedy. Just to properly show you when we do this and we select the genre, you'll see that comedy, even though it starts with a C, is under drama. And we've already seen this before when we were trying to sort out lists and letters and so on and so forth and Python that the upper case are considered to be before the lower cases. So how do we make sure that the comedy and documentary appear in the correct positions? We can do the following. We can select star from genres ordered by genre name. And then we can specify that collect no case hit enter. And as you can see now, documentary appears before drama and comedy appears before crime. Because a appears before R and also appears before. That's obvious. As you can see, we don't use any case. We can also add an extra option in here and that we can present it in a descending way or descending manner As you can see. Now drama is at the beginning. And then we have documentary crime, comedy, and action and adventure are listed at the end. Pretty simple, nothing too much in here in case you want to display things in a different order or using a different parameter as an order if you want to display them without any case. And also you can display them in descending order. Now I have a bit of a challenge for you to sort out the movies. Select all the movies from the movie table. Sort them out based on the genre and the movie title. This is something that you can look up. The case should not matter and they should be in descending order. I will give you a hint about the second point where you should display them or order them based on their ID and their title. If you want to go search for this yourself, go ahead and do that. If you don't, I'll give you the hint in 321 at a common between the genre ID and the title. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? In here we want to select star from movies and then we want to order order by the ID. We start with the Genre ID and then the title. Collect, case Descending, Hit Enter, and there we go. As you can see, the Genre ID in here are 111-122-3344 And then we display them, first of all based on the genre ID, but how would we order them next? Well, we ordered them by the title, so you'll see, because we have and then we have numbers at the end. Why? Because we are using the sending order. If we were using the normal order, we would start with the numbers first. Same thing holds true right here in these two movies. Unfortunately, they both start with the same. Letter. And they have almost the same name, except for the godfather at some point. Or the godfather part two has the column right here. Another example would be the threes. Right here we have two threes. They are also, we compare the D and the ABC D. D appears first, but because this is descending order, we present the good, the bad, and the ugly first. This is the order. Nothing too much in here, very simple. Let's try this in a slightly different way. Let's try to print out the actors. I'm going to select star from actors. Or by, by the way, if you don't know what we have in actors, again, you can use the schema. If I scroll up, look at actors, what do we have? Oh nice. We have the movie ID, We have the first name and last name. I'm going to the first name and then come up movie ID. Yes, that is enough. There we go, these are all of our actors. You can see it starts from here. Sometimes this might be confusing, but through trial and error it will be very easy for you to spot. So you'll see, first of all, we have Al Pacino and we have two Al Pacinos. Why? Because they act in two different movies. They act in the Godfather part two. And in the Godfather you'll see even the connection. Because notice, and this is very important for you to understand right now on the actors. Right here on the actors we have the foreign ID, which is the movie ID. References movies. Movie ID. So there is a connection between Al Pacino to the ID right here and the godfather, very important. So there is a connection between the movies and the actors. And then we also have Al Pacino Nine because he stars in the Godfather part two as well. Ladies and gentlemen, thank you so much. I apologize, thanks so much for watching so far because now we're going to talk about the join and what is the join? The join is basically going to allow us to create the connection between these two movies ID, the movie ID on the act, and the movie ID on the movies. The join is used to combine roads from two or more tables based on a related column between them. So in our case, the related column is the movie ID. Here are the most common types of join. So we have the left joint, full outer join, and left join if null, right join, if null, right join, and inner join. All of these are different joints, don't worry for now. What we are going to be focusing on is the inner join. All of the other ones are for very special cases. 90% of the time you'll be doing inner joints because you want the connection between these. What's in common between the two tables or combine the roles between the two tables where they have related columns. Let's take an example to make this more clear. Let's go back into our command prompt. In here, I'm going to select at first name. The reason I'm doing this is going to get very clear and a few. First of all, I want the first name on the actors from the actors table. This is indicating the table. Next I want to get the actors last name. So keep in mind, and in here, this should be last name. Come on, and then I want the movies title. I'm getting the first name from actors, the last name from actors. And the title from movies. Now, where am I getting these from? Well, of course I'm getting it from actors, but that is not enough. Because I'm not just getting it from actors, I'm getting it from actors. Join movies, it's joined together. And then I'm going to say on what are we joining these on? What is the connection that we're trying to create? It's on the actors do movie ID, where it's equal to the movies movie ID. And there we go. So as you can see, we've never before had the actor and the movie displayed in the same table. But we've created this display ourselves. So we've printed out the first name, last name, and the title. For example, Tim Robbins, The Shawshank Redemption. Let's take an example. Here we go. This is Tim Robbins, right here. You can see Tim Robbins has his own personal ID. The actor's idea of one first name is Tim, last name Robins. He was born in this date. He is American and his movie ID is one. If we go to the movie stable, where is the movie stable? This is the movie stable right here being displayed. If we go to the movie stable, what movie has their movie ideas? We I want you to find it. It's the Shawshank Redemption? That's correct. This is the movie ID. Our command in here said the following. I want to select the first name, last name from the actors and the movie title. This is why we have the display. The second part is where do we want to display this from? Where do we want to get this information from? We want to get it from actors join movies. We're getting it not just from actors, we're getting it from actors joined to movies. And how are we joining these on the actors movie ID and movies? Movie ID. I understand you're probably very confused. Like Michael, what the hell is happening? Like I just learned the order by now. You're throwing all of this information on me. I understand the join is not something easy to master. But again, like always, you've come this far in the course. You should trust me that at some point it will become very intuitive. The most important thing is to understand the connection being created. For example, George Mckay is British with ten their movie ID, which means he acted in the movie. Where's the movie? So these are the movies he acted in 1917. What should be the output at the bottom? Let's find, who are we even looking? George Mckay. George Mckay. If we look to where is George? Actually, I can't find George anywhere. There we go, 1917. So very important that you understand the join before we move on. Something very important is that when we say join, we automatically mean inner join. Okay? Because we're only getting the things that are in common from both sides. Very important to know that we're getting the inner join Finally, in here, let's say we want to get these, but we want to create a certain order. I will remove the semicolon from the end and I'm going to say order by and then movies, title actors or actually know what, let's do act, first name, title. There we go. So we start from the top. Al Pacino, the godfather. Al Pacino the godfather part two. You should have seen this coming because in here, look at that right here, when we had these two, we had 2.9 which means the Godfather and the Godfather part two. You can see from the movie ID, when we scroll down, this is what we get. The Godfather and the Godfather part two. Ladies and gentlemen, some of you might be going crazy. Some of you might be excited for the challenge. Some of you are like, I did not sign up for this. What the heck is happening? Trust me, everything with time will fit into a place. All the puzzles will fit into their place. Just take your time, fresh breath of air, and then look back at this. Understand how to join works. Try to test a few things out. Try to see how you can mess things up. Don't worry, you have the backup, you can always restore it. So thanks so much for watching. In the next video, we're going to be delving deeper into joint queries. So make sure that you understand it right now before you move on, and I will see you in the next video. Bye bye for now. 140. 6. Chaining JOINs Queries : Welcome back my fellow Python programmers to a brand new video. In this one, we're going to be chaining multiple joint queries together. Now we're going to start writing more complex SQL, and that means we're going to be maybe making more mistakes, which means that we will have to reorganize our code in a better way. And when we are working with command prompts that's not really flexible and possible. What we're going to do is we're going to create a new text document inside of our movie database folder, which is going to be the query test file. This is where we're going to be writing our SQL queries and then we're going to be sending them to the command prom. That way if we make a mistake, we can then copy it from the text folder. And I'm going to show you what I mean by that later on. First of all, and here we are going to select from the genres and the movies and we're going to join the movies and genres. I'm going to select the genres, genre, name movies, movie, it was just title. And it's going to be from what movies interjoinenres on movies, genre ID equal to end, sorry, genres, genre D also in here. I'll just enter and I will order them by genre, do genre name. I just made a huge mistake in here and I know that I made the mistake, but I made it for a specific reason. I've written them. I was thinking of them, but I just written them. Let's say you made a mistake, how would you fix it? You cannot go back in here and change it. That's impossible. And if we go back with the arrows, you'll see that we can only get certain terms. So we will have to rewrite a lot of things. So what we can do in here, and this is where the SQL text file that we created comes into play. We will select this, we will open up the text document and we will paste everything in here. And of course, we will remove this arrow. Now, I can simply fix this by removing it. Copy this, and then paste it in here. And hit Enter. There we go. Very nice. Again, No such column as genre, genre name. Where is that? I'll write very nice. We changed this once, copy base, hit Enter, and there we go. So as you can see, this is a very helpful tool to save everything that we do inside of a text document. And maybe sometimes you want to redo a few of these. Having this is a very helpful tool. Great, let's now see what would happen if we wanted to access three tables at the same time. Instead of just two, we are going to try and print out the genre, the movie, and the actors at the same time. So let's go ahead and do that. First of all, what do we want to display? We want to select genres, genre name, Okay. Then we're going to get the movies title. Then we're going to get the actors first name. Actors dot last name again. Remember when we're working with the names of our fields, It's okay. It doesn't matter if we have upper or lower case letters and then from actors, right? But of course, this is not the end, because on actors, let's go to the top and see what we have in the scheme when working with actors. We have first name, birth date, and then we have the four and key which references the movie ID. What should we be joining on in here? Well, of course we should be joining on the movie ID in the actors to the movie ID of the movies. I'll scroll down, since we are already getting things from the actors. I'm going to create an inner join with the movies on the movies. Movie ID. Equal to equal to actor movie ID. Round of applause For the shark anti virus for keeping us safe. And this is not sponsored by Shark. Unless they want to contact me and give me some money, then yes we are sponsored by Shark, VPN. Anyways, inner join on the movies and the movie ID. Movies movie ID with the actor's movie ID. Now the next thing is we want to get what the genres and where are the genres. Again, if we scroll up, I know this is a bit cumbersome, but this is necessary in here. What we have is the movies we have the genre ID, and then in the genres we have genre ID. Perfect. So we're going to join on these please. I do recommend that you take a few seconds in here to fix this as well, or do it yourself. So in our join, genres on movies do moved equal to genres, genre ID, and I really hope that we make a mistake here. And finally, why do I hope that we make a mistake? Because I want to show you the power. Okay, thank you. I mean, this two scans in a couple of minutes. I mean, that has to be a record. They're making sure that we're safe. Anyways, I want you to take the time to really appreciate what is happening here and how we are connecting these. And I hope you make a mistake to show you the power of using the text document that we just created in here. We want to order by genres, genre name, and then by the movie title and then by the actors dot first name. And I think that's enough. So let's hit Enter. And there we go. We have everything correct. But just in case I'm going to copy this, Just put it in here if you want. You can also add like a description of what this does maybe above it. That would be very helpful, but I will just keep this right here and then control S to save it. There we go. As you can see we've joined on the movie ID in the movies to the movie ID in the actors. We were able to associate every single actor with their movie. Then we joined the movie ID with the rest genre ID. There we go. We did make a mistake in here. Something is definitely not correct. Let's try and figure it out. What we did was we joined the genres on movie ID and then G genre ID. That's why we don't have all the, and we have some weird things in here happening. Let's change this again. We have comedy. Schindler's List is definitely not a comedy. And documentary doesn't work. We made the incorrect thing. What we had to do in here to fix this is we would have to get select, then go to the inner join, then the second inner join, et cetera, et cetera. Obviously, we don't have time for that. Instead what we can do is in here, just change this to the genre, now we can simply copy this, boom, pasted in here and head enter. All right, there we go. So now we have everything set up correctly. The action, the adventure, the crime, and the drama. So as you can see, saving very, very crucial. So what did we do in here? We associated the movie ID on the movies with the movie ID on the actors. So we created the first connection, then we created the second connection from the genre ID on the genres, with the genre ID and the movies. And we got everything written correctly to us. I hope you enjoy it before we go, there is a bit of a challenge in here for you. So we want to get only from a single movie, so we want the same result that we just got. Meaning that we want the genre name, the title, the first name, and the last name of the actors. But we only want the actors from Pulp Fiction to display here. The challenge here is to know where to insert the query. Get it where The important part is where to insert this. Pause the video right now, and get all the information. But only from the movie Pulp Fiction. Welcome back. How did you get on with that? Basically in here we will not copy everything. We will copy these first three lines because they are exactly the same. We will hit Enter, and now we're going to say where movie title equal to Fiction. I hope I've written Pulp Fiction correctly. And then in here I will copy the last line because I'm lazy and hit Enter Error. No such movie C. This is exactly what I mean. Mistakes can always be made, especially when we're working with SQL, where the slightest mispronunciation can lend you in big trouble. Let me remove these, save a copy, paste it, Enter, and there we go. So now we have all the actors from the movie Pulp Fiction. Ladies and Gentlemen, I hope you enjoyed this video. I hope you understood the importance of using the text files. In the next video, we're going to be looking at like wild cards and creating views. Very exciting stuff. I can't wait to show you how all of that happens. Thanks so much for watching and I'll see you in a few seconds. 141. 7. LIKE Wildcards: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be looking at like wild cards and how to create views. First of all, what the heck are we even talking about? Let's say you're not sure what the name of the movie that you're trying to look up or print out the information of, but you know approximately what its name is going to be. This is where we would use something called the like. So first of all, let's do the following. I'm going to go, first of all, let's try L S in here. Okay? That does not work. We need to quit. And then open it up again. You know what? Let's just keep it as it is. It's okay. And here I want to go back and I want to get the following. I think select border by genres. Yes, I think this is good enough, So I will print all of this out. Okay, so at this point, it's a good idea to start putting our codinsXDfile because it's going to be much more extensive. So if you haven't started doing that yet, I recommend that this is the point where you do so in here, let's say we want to get all the movies with the word or whatever you want to call it, for example, the Godfather or the Lord of the Rings. Or for example, we don't want Pulp Fiction in this case. The way we do this is the following way. I'm going to copy this in here. I'm going to change the swear the movie title two or the movie title equals to, to where the movie title is, like where is it, this and then the percentage sign again, don't worry. I will explain to you what this means. So I will copy and paste it in here. And when I hit Enter, you'll see that all the movies with the in them are going to appear. Everything that doesn't have the will not appear. This is wildcard. If you want to first we use the keyword. Instead of the equal second, we use the percentage character, which is called the wildcard. Hence the name of this video, wildcards. And a third thing, you can also use like without any wild cards. So for example, if the word just like in here for example. If we just remove these wild cards and we will be then looking for a movie that is of title. But let's look a little bit deeper into wild cards because there's something other than the percentage. Wild cards are a special character used in pattern matching within the queries. So you're trying to match a pattern in your search for specific data. They allow you to perform flexible and powerful searches by representing unknown or variable parts of your string. There are two wild cards. The first one is the percentage sign, which represents any sequence of 02 more characters, Like you might have one character, two, or maybe none of them, just nothing inside and the underscore which represents any single character for that matter. Okay. So with that out of the way, of course in this case we wouldn't need, where's the query? We wouldn't need the percentage sign behind that. But we were thinking of the idea that maybe we want this to appear somewhere inside of our word or the movie title doesn't have to be at first. Obviously, all of the movies that we have have the start in the beginning, but maybe it could be in the middle. So that's why we use the percentage sign on the left hand side as well. So with all of that information, now it's time for a bit of a challenge. Your challenge is going to be to find something like this. Find all the actors who have a first name with only three letters. Interesting challenge. Print out the title and the year they were released in, of the movies whose directors have a ran somewhere in their name. These are two completely different tasks that you need to do, okay. So first of all, do the first one, then print out the title and the year they were released in the movies whose director have somewhere? Get the directors that ran somewhere in their name and print out the movie title and the year the movie was released of the directors that have an somewhere in their name. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? First of all, we need to select star from actors where the actors do first name like underscore. Underscore. Underscore. There we go. So when we hit Enter, as you can see we have Tim, Tim, Ben, Eli Lee, and Lee. Very nice. These are all the actors with only three letters in their first name. Now we need to get all the movies and the year they were released in, when the director has a name that has in it, we need to select the title. Release here, is that how this is called? First name title. Okay. No, it's not here. We'll have to go more to the top. Let's just go to where. Okay. There we go. Movies. We have the release here. Yep. There we go. And the director. Okay. Perfect. Release here. And then from movies where percentage ran, percentage closed the parentheses. Sam Colin, hit enter the Shawshank Redemption. Actually know what a good idea here would be also to print out the director's name, the as well. All right, so we have Frank Arrabon. You can see we have Ran, we have Francis Ford Copola. We have Quentin Tarantino and another movie by Francis Ford Copola. And these are the movies. So ladies and gentlemen, this is a quick one, this is a very important one as well. In the next video, we're going to be looking at creating views. So thank you so much for watching. I thought it would be in this video, but apparently not. I apparently found that it is too long, so I had to create two videos instead. Thank you so much for watching. I will see you. And the next one. Bye bye for now. 142. 8. Creating Views: Welcome back my fellow Python programmers to a brand new video. And in this one we'll be looking at creating views. Let's talk about views and what they are. Views are virtual tables that are based on existing tables. If we want to combine one or more, if we want to combine two or more tables, we can combine them into a virtual table, that is a view. They allow us to group together data from multiple tables and presenting it in a way that is easier to understand. Views can be used to simplify complex queries, height sensitive data, and grant users limited access to certain data. To create view, you use the create view statement. After that, I'm going to give you a challenge directly. I mean, who doesn't love a video that starts with a challenge? Your challenge is to create a view, you'll need to create a view, name it, movies underscore title or movie underscore titles. It should have all the movie titles ordered by their title. Check how you can create view search, Google four creating views, and SQLW three schools. Even though I showed you a bit of help with inter pass the video right now and go do the challenge. Okay, welcome back. How did you get on with that? From here I'm going to create view and then movie underscore titles as then I'm going to select title from movies. And then order by the keep liners I now giving by the title head. There we go. Now if I select star from movie, underscore titles, look at that. We have just the title from all the movies and look, we selected everything. So this is how we start looking at views. They simplify complex squaries. Okay? Even though this is not a complex squary, but it does simplify the query. It also hides sensitive data. So for example, the Genre ID. Maybe we don't want people to have access to the genre ID. Now we've hidden that sensitive data. And it also granted users limited access to data. So for example, let's say we didn't want the users to see the year the movie was released. I know bear with me, these examples are a bit absurd but still gets the point out there. Maybe just replace the genre ID with a password and the release year with, I don't know, location or something live location. It gives users limited access to certain information. And it's simplified like look now these three lines are a single line. We can select everything very easily. Actually, let me copy this and put it in our text file in here just so we know how we created this view, even though it's not very complex, but still could come in handy later on. With that, out of the way, let's look how we can maybe destroy or delete a view. I'm going to drop view underscore titles. There we go. Now if I try to select star from movies titles there you see no such table. Let us create it again, but this time with a few modifications. I'm going to set this right here. I'm going to make sure to title and make sure that there is no case as well. Boom. There we go. Select star from movies, or why is it like this? Where's the actual select star from movie titles? There we go. Even though there's no case in here. No problem with the case. I just thought it would be a good idea to add this. This is very simple. This is not something that we would really like. We want to look at a better use of our view. Let's go ahead and create a more substantial, more complex view and see its use. First of all, I'm going to create view and call it the Genre Underscore List. And we're going to say that we've created the view list as, then we're going to select Genres, Genre name as genre right here. Notice that we had the title as title, but if we had something else, what would we call it? Now we have specified that we want the genres, genre name to be represented as the genre, then we want also to have the movies do. Title as movie name. Maybe then we would like to have a first name and I think first name will be enough or should we add last name? Yeah, let's just stick with a last name from actors. Let's just, yeah, let's just keep it first name and last name. No need to change anything in here. I think from actors hit Enter. Now we're going to have an inner join of the movies, and you should know this by now, of the actors. Movie ID equal to movies, movie ID, hit enter inner join of the genres on the greenD equal to movies, genre ID and we are going to order by Johns name, movies, title and actors do first name. Great. I will copy this. I will paste it in here and we'll remove this one. This one. This one. This one. Okay. What is the problem in here? It's telling me that are movie title as Oaks movie name. Okay. It doesn't like having spaces. So we'll have to maybe make an underscore, or let's just call it movie. Why go through all this hassle right here? There we go. Now if we try to select Star from the genre underscore list, look at that. We have this complex query printed out using just the simple line of code. Now we have a view, which is a virtual table, which gives us the following information. And this is going to be very helpful in the next video where we will have a few challenges for you. It will be a very special video with lots of challenges that you will need to find on your own. Thanks so much for watching. I hope you enjoyed. I hope you understood the use and the usefulness of having views and virtual tables. That's basically, that's everything that I have to say. In the next video, we're going to be looking at restoring backups and a few functions and also a pack of challenges to finish off with database so that we can move on to using Database and SQL in Python. Thanks so much for watching. See you in the next video. 143. 9. Restoring Backups and Function: Welcome back my fellow Python programmers to a brand new video. And in this one will be restoring backups and looking at functions. And as I told you, do the big, big challenges first of all, in here, as we've said, we have already created a backup for our movies, but we want to create another backup. So we'll have backup then movies underscore, back up. Wait, let me just check. What did we call the first one? Movies back up one. Movies back up, one. Okay, so this one will be movies back up to. Now we have a second back up which is movies back up to Excellent. Now we're going to delete from actors all the nationalities or all the actors that have an American nationality. I'm going to delete from actors where nationality, is that what the name actually, let me copy this. Let me delete it and do the schema again. Okay, thank you for that schema. Okay, what do we have for the actors? Yes, it is indeed, nationality control. Nationality is equal to American enter. Now if we select a boom, we'll see that we don't have any Americans in here because we've deleted everyone. Now let's try and delete everyone who is not British. We'll see that we have an Australian, and an Irishman, and a New Zealander as well, which is Peter Jackson. Let's try and delete everyone except for the British. The way we do this is actors where nationality is different than the British. British. Now, if we select star from actors, you'll see that we only have British still left. Let's go ahead and do the following. I'm going to also show you the count. We select count star from a boom, you'll see that we have nine actors left. 12,345,678.9 Let's do the same for the movies to see how many movies we have. I believe we have ten. Boom, exactly. There we go. And then finally let's do the genres. And I think we had six or six. There we go, very nice. Let's do the restore movies underscore, back up to boom, and now if we count the actors again, there we go, we're back to 39. So as you can see, restoring is very helpful. That basically, of course this doesn't cover all of SQL. Sql like would need maybe hundreds of hours to make sure that we understand every single small nook and cranny, but this is basically SQL. In the next video, we'll be using database inside of Python, meaning inside of Intelligy. But before we go, I have a series of challenges for you. First of all, you need to select the names of all the actors on the movie Pulp Fiction. Second, you'll need to repeat the previous query, but this time display the actors in name order. Display all the actors in the genre. Action set Al Pacino's nationality to Italian. Select the titles of all the movies in the drama genre in alphabetical order, include only the title and the output. Count the number of those movies. Search the Internet to find out how to get a list of the movies from step six without any duplicates. This is a very cool one. And then search the Internet again to find out how to get a count of the movies without duplicates. Also, I recommend that you always keep the view that we created. So we've created two views, the genre list and the movie titles. So think of how you could use these views to your advantage in some of the later steps past the video right now. And try to do your best to do these challenges. Because if you can do these challenges, it means that you've become intermediate at SQL. Not super advanced, but intermediate and above. And you know a lot about SQL at this point. Of course, with more practice, with more examples, with real world examples, and when we go through it in Python, it will become much, much more evident for you. But for now, try your best to do these challenges. And I'll see you in a few minutes. Okay, welcome back. So how did you get on with that? Let's first of all look at select the names of all the actors on the movie, Pulp Fiction. This should be fairly simple, we just need to get all the actors. We'll select act, first name, actor, last name, then where from actors. And then we'll create inner join of the movies on actors. Movie ID equal to movies, movie ID, then where the movies title is equal to Pulp Fiction. All right, there we go. So these are all the actors from the movie Pulp Fiction. And obviously, we needed to create an inner join just to make sure that we have the same movie ID, where we have Pulp Fiction as the title. I will save it. Right here. There we go. Save that. What do we need to do next? We need to repeat the previous query, but this time display the actors in name order. This should be pretty simple in here. I will just copy these lines. Actually, let's just write it in here. We need to order by name. Actually copy this and put it right here. Copy this and put it right here, and boom, as you can see. Bruce Willis, Harvey Keitel, John Travolta, Samuel. And there we go. Yes. Abc, D, E F G H I, J K Mano Pi R S, T U, V, et cetera. Let's continue on and let's look at three. Display all the actors in the genre action. Very nice. Again, we go back in here, let me actually use the arrows to select the actors first name and last name from actors. Then we're going to create an inner join to the movies because we don't have access to the genres from the actors. In order for us to get all of the action actors, we need to first get all the action movies. First of all, we create an inner join of the movies on the actors movie ID equal to the movies movie ID. Then we create a second inter joint on the genres or with the genres on the genres. Genre ID equal to movies genre ID, where we have genres, genre name equal to action. Uh huh. Very nice. We have an error. No worries. We copy this, we paste it in here. You know what? Actually, just for extra safety, so we know that we have the movies, we're going to get movies. Movie, it's just title then genre, genre name. This is for extra protection. And what was the error? Not extra protection, just to make sure that we got it correctly. And what do we have in here? The error was no such column as movies do genre D, where did I write that? Genres ID. Okay, movie, genre D. Yep, there we go. So if I copy this, paste it in here, Hit Enter, and let's see, the first name, last name, title and genre. The Dark Knight, The Dark Night, the Good. Deb and Ugly. The Good and the Ugly. Yep, there we go. Do we have anything else? Let's try select star from books, from movies. Let's see, we have what's even the genre. Let's select the genres as well. The genres we have, action is at three, so we have two. Okay. Yep. So there we go. We made sure, I'm just making sure that this one right here is correct indeed. So we only have two action movies, which are the good and the bad and the ugly. And we actually got all of the actors for that very nice. But in this situation, we could have done something even better. So remember the genre list that we created? Let's select, oh my God, select star. From the genre list of view that we created, but as you can see, we already have the actors associated with a genre. What we can do in here is we can say the following. Select first wait, let me check the headers. Okay, first name, last name, Genre. Underscore list, where I believe it was called the Genre. The Genre is equal to action. And look at that. We got the same output as we had in here, Christian Bail, the dark night action. Let's see, there we go, Christian bail. Now, obviously we don't have it, but it's Christian bail, Heath Ledger, Clint Eastwood, whatever it was. Three or four from the dark night crisis and three from the movie at the bed. And the ugly, how cool is that we were able to do. Look at how big this one was. Oh my god, where is it? Yeah, it can get a bit confusing. So there we go, look. We had 1234 lines of SQL because of the view that we've created. It was done in one. Yeah. There we go. Next we need to set Al Pacinos nationality to it. Let's go ahead and do just that. How do we do this? We need to do the update. If you remember, we need to update actors and set nationality equal to it, where first name is equal to all and then select star from actors. Al should be at the top. Oh, no, he's not in here. Al Pacino now, is it? He's no longer American Al Pacino. Where is the second time is only one time. No, he's not. We've seen him appear multiple times. We just need to find Al Pacino who is Italian as well. There we go. Number four, done. Challenge number five, select the titles of all the movies in the drama genre in alphabetical order, Include only the title in the output. Again, this is where you can start thinking of the view that we've created because we already have a table or a virtual table where we have the movie and the genre in the same place. If we go back and here we can do the following. And I believe it was movie. Yep. Movie, not the title. Very nice. Also something very important to keep in mind that the view, you might have a change in the name of the headers. Select movie from genre underscore list where the genre is equal to drama. Was it drama? Yes, the drama genre drama hit. Enter Boo. There we go. Movie 12 Angry Men. And notice what we have in here. We have duplicates. And why do you think we have duplicates in here? Why do we have four Schindler lists, two Shashank Redemptions to 12 angry men? That's too many angry men. What is happening? Well, if I do select star from underscore list, you'll see that for example, okay, action. As you can see, the dark night appears three times. 12 Angry Men appears twice. Schindler's List appears four times. Why? Because for every actor we have to display the genre and the movie title. So how do we avoid this? Avoid this with challenge number six. Challenge number seven. First of all, we need to count the number of these movies. If I go back in here, I go back to this one, and in here we select the movies, but this time we count them. Instead of displaying them, count, boom, boom, boom, and we have ten. But obviously that is not true. We have ten because we've counted these multiple times in challenge number seven. We need to make sure that we get them without duplicates. I hope you tried your best to look this up on the Internet. So the way we do this is right here. We need to add the following. Select distinct movie from genres list. There we go. Now if we try to count it, but notice this is also a very important part. How do we count these distinct ones? We need to count the distinct ones. There we go. Now we have four. And that is the end of our series of challenges. It is the end of the use of a command prompt to work with databases. I hope you enjoyed. I hope you learned as much as possible. If you're still not sure, please go back and review this. Using SQL is mega mega important? I cannot emphasize it enough. Thank you so much for watching. In the next video, we'll be looking at databases SQL and Python. I can't wait to start or to go back to our Intelligent, to go back to Python and to use SQL with Python and blend our two tools together. Thank you so much for watching. I hope you enjoyed and I will see you in the next video. Bye bye for now. Oh, also leave me a review. I mean, if you don't have anything, if you're satisfied with the course, come on, leave me a review. Contact me. Tell me how great it is. Let's go. 144. 10. Commit Changes: Welcome back my fellow Python programmers to a brand new video. And this one will be actually committing our changes through connections, cursors, and making transactions. Let's go ahead and get started. First of all, we're going to create a new Python file which is going to be contacts number two. Contact two, enter in here. I'm going to import escult three. I'm going to create the database connection and say that it's equal to escult three connect and it's going to connect to contact, sorry, cult the one, the database that we've created. I'm going to say four row in B execute or execute because I don't want to create a cursor yet. I'll tell you the difference between the cursor and the connection. Select star from contacts. I will print out the role and I will say Db close. If we run this we should, we don't get anything that's weird. If you were expecting to get all of the information printed out, nothing happens. The problem is not with the code. The problem is that we did not commit our changes and it's different than writing to a file. Let me explain to you what that means. Back in our contacts, we've created a table, we've inserted information, but we haven't really committed our changes. Do you remember when we were working with prompts and we did the schema? You can even test it out on your own command prompt. We did the schema, actually, let me try to see if I can replicate this. Let me try to ask you light three, test B and I will do schema. I hope it shows up. That doesn't show up. I will have to open the movies folder for now. I just don't have the time. I recommend that you try the schema and you'll see that the last line has the semicolon, the function commit. Because whenever we make changes, we have to commit those changes. If I do, b commit right here, now we've committed the changes. Now when I write click and I run, if I go back to contacts two, write click and run. There we go, we have all of the information, how cool is that? But let's go ahead and dissect this slightly. So instead of just having the row in here, I'm going to have the name, the phone, and the E mail. I will do and print these out, just like we've done before. Actually, let's make it the dash, It looks more appropriate, more user friendly. Right click and run. And boom, there we go. We have all of the necessary information. And keep in mind we don't need to commit the things in here. And I call them things on purpose. Why do we commit the things? Because we haven't made any changes. We don't need to commit those changes. Okay, so let's go ahead and now try to update a few things inside of our contacts too. In here we've created the connection with the contacts. Let's go ahead and do a few things. I'm going to update underscore SQL, and this is going to be our SQL querian here. I'm going to update contacts. Set E mail equal to update at update.com Where, let me get rid of this. I'll put it down here where the contacts do phone is equal to. Let's change Michael. There we go. Now I'm going to create the update underscore cursor and say that it's equal to b cursor. Then I'm going to do the update cursor, execute update SQL. I will print out that, let's do it like this replacement field, I will say the updates, I will tell you what this does. Updated. And we need to make sure that we close the cursor right here. After we finish update. Cursor close, Actually it's better that we put all of these at the end. We close the cursor, close the database. If we look at what the row count does, let's hover over this, okay? It doesn't provide you with anything. I mean, you can look at the documentation if you want, but basically it tells you how many rows were updated. Right click and run. And we should see right here that was updated. And you can see it was of Michael With that out of the way, if we issue you a challenge to make some changes, you should be able to do it, change the phone so it doesn't match the one that we want to change. And by the way, you should know by now, because we haven't committed anything. If we do the following, for example, we'll see that the e mail goes back to what it was. Of course, we have an error because we're trying to close a cursor that we haven't created. But there we go. Now your challenge is going to be to change the phone so it doesn't match the one we want to change. Remove the entire Were query and of course, test it at every point. First of all, change the number so it doesn't match. Then run it. Then try to remove the entire query. Run it. Create a new Python file called checkdbtpy, and print out the list of all the contacts. And remember I said the list. And then what did we get as the output? Pass the video right now and go do the challenge. Welcome back. How did you get on with that? I'm going to change these. 6958-69 2047. Now the numbers don't match. If we write click and we run, you'll see that we get zero rows updated and we have still contact at two python dev contact. Obviously nothing gets updated because we don't commit our changes from before. The next thing to do is to remove the entire Were clause. What do you think the output is going to be? You should know this from all the work that we've done. In the prompt, the command prompt, try, click and run. Boom. There we go. Because we haven't specified where we want to make these updates. It made the updates everywhere. Now, before we move on, the excuse me, we need to create a new Python file and call it check DB in here. We're going to import escult three, we're going to create the connection. And this time we'll call it connection, not just database. And then contacts lite, excuse me, Contactes Lite. And then we're going to do, I said list, right? Let's print them out. Normally, if you did print them out using the fetch all that's okay. I said list but I just changed my mind. Four in connection execute and we are going to select star from contacts and print the row, and I forgot the two dots. And of course we need to close the connection. If I write click and I run, look at that. I still have the old e mails and you know what? I just want to copy this. I like having a good structure in here. Even though we've made the update in contacts to it didn't work. Why? Because we haven't committed our changes. How do we commit the changes? We've already committed the changes. Look back at it in here. Before we close the update cursor, we need to do update commit. Oops. But we don't have it because we first need to do connection commit. It should work if we do the commit directly on the cursor, there we go. We can see that we cannot. On the cursor, we need to do it on the connection. Now if I write click and I run, there we go. We've made the update to everything. If we do check B, we should get, there we go, because we've updated or we committed the changes. The changes also happened in the check. We've officially destroyed our beautiful database and here and made everyone have the same E mail update. And just before we move on, I want to show you one more thing in here in the contacts right here. I want to show you that the connection from the update cursor is the same as the connection that we have in here at the B. I'm going to do a print in here. Just print and then I will print out are the connections the same replacement field, Answer this is a replacement field and I'll say update cursor connection is equal to B. And this basically should return true if it is and false if it's not. And yes, these are the same connection. Thanks so much for watching. I hope you enjoyed something we didn't talk about is that two roles were updated because we removed the word clause. This is something I forgot to tell you, but it should be obvious by now. Thanks so much for watching. In the next video, we're going to be looking at hacking. Sort of kind of, it's not officially hacking, but I'll show you how vulnerable our database actually is. It can be easily exploited. So I will see you in the next video. Thank you for watching you. 145. 11. How To Hack (Kind of): Welcome back my favorite Python developers to a brand new video. In this one, we're going to be looking at how to hack. Not quite how to hack, but just an introduction of what happens behind the scenes when somebody tries to infiltrate a database. Let's go ahead and get started. First of all, back in contexts two, we want to create a new update in here. I'm going to create another update. Where should I do it? I think I will do it right here, just above the update that we had. And I'm going to create the new underscore e mail and it's going to be another update at.com Then in here, I'm going to have the phone number which will be equal to 65. What was the actually, let me just comment this out. Right click and run. What number did I have? Let's copy this one. Paste in here and then co, And then I'm going to say that the update contact set e mail to be equal to the replacement field inside. I will have the new e mail. That should be it. Oh, and also we need to make sure that we only update where the A phone is equal to replacement field and then the phone, this should be good enough If I write Click and I run, I should see that I have another update right here on Michael where the phone number is different. All right, so now that we know that this is working, the next thing we want to do is we want to change this phone from just the typical phone to an input, let's say the user wants to input which person or data entry they want to change. In here I'm going to change this, Please provide me with the phone number, two dots and in here I'm going to call this another update input. And I'm going to call this one input, just so we always know to distinguish between each and every single update. Now if I write Click and I run, you'll see, please provide me with the number. I will hit control V. Okay, that did not work. What was the number again? I have no idea. Let's redo this real quick. And now it does. Okay? Let's duplicate this. If we comment this out, it will also work. You know what? Let's check B. Right click and run. Okay, copy the number. This is no longer needed. This can be uncommented. Right click and run past the number. Hit Enter, and there we go another. Update Input at update Input.com So we were able to change this e mail. All right, this looks great, but one last thing I want to do, and that is I want to update or execute the update SQL using not execute, using the execute script. And basically what the execute script does is it allows us to execute multiple lines of SQL commands. So for example, in here we just have a single line which is the update SQL, meaning that this is the only command that we're providing it with. What I mean by here is for example, somebody can have a Sem column and then continue with another update. You know what I mean? That is the purpose of using the execute script. It allows you to have multiple executions. But for now we don't want just this. I want to, okay, I want to print out the update SQL actually in here, I might want to create a print just so we can have an empty line of code. This is going to come very handy later on when we actually start hacking. But for now, I'm going to tell you a little bit about SQL injection and what it is. Sql injection is a type of attack where an attacker can inject malicious code into the SQL query. So they inject malicious code. And you might now have started forming the idea of what's going to happen in a few minutes. So this malicious code can then be used to gain unauthorized access to a database, modify the data, or even delete data, which is the scariest part. Sql injection attacks can be carried out by adding special characters or queries to a user's input field every single You know, like when you're trying to work with the database, usually the user has the option to search through this database, send in SQL queries. Not directly obviously, but when you do click on a button to search, I don't know, through usernames or to find your friend on Facebook. Usually this is an SQL query or it gets converted into an SQL query. What the attacker does is they inject a malicious code into that search engine, which then produces some result and gives them access. So for example, you can use a single quotation marks, get all the roles in the database. This is something that's very scary, and I'm going to show you a few of these ways of access. But before I show you, you have to try and hack the database yourself. How about that? Instead of just providing the number, I want you to provide it with some malicious code. And what I want you to do is to delete the contacts table. Interesting, isn't it? I'm going to give you a hint of how this would work. For example, if we have the number, I then want you to add a semicolon and type in drop table contacts. Then I want you to go into check B, and I want you to run it. And I want you to tell me what the results that you get are. Pause the video right now and go do the challenge. Welcome back my fellow hackers. How did you get on with that in here? What I'm going to do when I write Click and I run, is I'm going to provide it with the number. And then I'm going to do semicolon drop table contacts and hit Enter. Oh, what just happened? First of all, we have minus one update. You can see what the actual SQL command or update was like. It had a semicolon and then dropped the table. And then when we tried to access contacts, what did it tell us? No such table as contacts. Something weird happened if I tried to run the B. Oh, I also get an error. So what happened? Well, what happened is that the contacts table was dropped, was deleted by our hacker. And this is not good at all. So now let's say the hacker doesn't know what the table names are from the beginning, they don't have an idea of what it is. Let me show you. First of all, I want to go into contacts and I want to run this again so that we recreate the table. Now if we go into check the B right click and run, you can see that we have our information and tables back. This is from running the contacts. I want you to see something. I want you to look at the following. I'm going to add a print in here and then I'm going to say four row in the connection. Execute. And then select star from cult underscore master. This is a scary, scary proposition because in here I'm going to print out the row. And if I right click and I run look at what I get. The Esculte master gives you a lot of information of what's happening. The hacker can use that information and they can use it to access all of the available tables. And even they can see how they were made. So they can see the actual fields. They can see the names, the phone, the e mail, and what type all of these are, and they can use that information to their advantage. That's a very scary prospect. Obviously, throughout the years, people have found ways of defending against such malicious injections. But one of the most simple ones is going back to contacts two and instead of having execute script, we can just execute. Now the reason why we were using execute script because as I told you, it allows you to use or to provide multiple SQL commands at the same time. Which led to us being able to drop table or to our hacker being able to drop the table. But what the execute does or the cursor execute, because remember this is the update cursor. What it allows you to do is it allows you to escape out and disregard any further SQL statements. Once you get to the first or once you get through the third one. Let's try running this again. If I write Click and I run and I provide the number and I try to drop table contacts, Hit Enter, you can only execute one statement at a time. Okay, this raised an error. This is not a very good thing to do. But at least the hacker was not able to destroy our contacts. Of course, there are much, much deeper layers to this. Hackers use tons and hundreds and thousands of ways to gain access to the information. But I just wanted to show you on the surface level what the SQL injection would look like. Thanks so much for watching. I hope you enjoyed Leave me ribbon. Leave me review somewhere. I would love to hear your opinion of what you think of the current lessons. And I will see you in the next video where we will be looking at placeholders and parameters substitution. So thank you for watching. See you in a few seconds. 146. 12. Placeholders and Parameter Substitution: Welcome back my fellow hacker developer, Python programmers. In this video, we're going to be looking at placeholders and parameter substitution. Which is going to provide us with a better way of allocating and providing inputs to certain database L commands and also help us in preventing SQL injections. First of all, I'm going to go back in here and I'm going to update this code a little bit. I'm going to duplicate the update SQL and comment out the first one instead of using this E mail directly, or what I mean by that is instead of using the replacement fields like we've always done, I will remove the F from here. And then I will replace this with a question mark, E mail equals question mark, and phone equals question mark. Then I will do the goal fashion format and in here we'll provide the new email and phone. Then here when I scroll down into the Execute update SQL, I'm also going to do comment and provided with the new E mail and the phone, The question marks are called placeholders and the extra parameters we've added to the execute is called sanitizing the input which checks if any extra queries are added and detects SQL injections. Now obviously, this is a very low level sanitation and this will not, again, prevent very experienced and high level hackers. But as I said, this is a start of you understanding how these levels work. From here, I'm going to first of all, explain to you, actually let's test it out. If I write Click and I run, please provide me with a phone number. Do we still have it? No, we don't. What was the number? Actually, let me go back and try to do this. Let's try to get this number. If I write click and I run, and I provide it with this and I try the drop table contacts, boom. As you can see, nothing was dropped. Nothing was updated. And we are good to go. Nothing happened in here and we've printed out the update, which is great. We did not drop the table. At least that was good. Let's go and talk about placeholders and what they are. Placeholders are special characters that are used to represent parameters in SQL statements. Just like we saw right now, placeholders are useful in preventing SQL injection attacks. They are similar to using replacement fields and print statements, or any strings for that matter. By the way, something that I did wrong. You don't even need the format in here because while obviously we're not using the replacement fields anymore, so I apologize for that. Parameter substitution is done using the cursor execute method. They are indicated by the question. Obviously, in the SQL light, these are very helpful. You can use them in the execute. For example, right now if I write click and I run and I just provide it with the number and I hit Enter, we should see that we have another update. If we write click and we run, and we try to provide the number with the drop table contacts, boom. Nothing. Oh, it does get updated. There we go. As you can see the oh, because we've already committed the changes. That's why we have this. Let's try to add a few Xs in here. Right click and run. And let's strike this again with the drop table contacts. Boom, there we go. It did not update even though we've provided the number correctly. But that is because we tried to drop the table. Let's try this again with just the number and we should have access. There we go. Very nice. So let me just take it back and that is enough. All right, so now that we've understood what placeholders are, let's go and try and use them when we're working in the check B in here. What if we wanted to get the information for only a specified name? Instead of getting all of the information from the contacts, let's just get the name of a certain individual. So I'm going to get the input in here and I'm going to say, please provide the name. To search for. I want you to pause the video and I want you to try and get this yourself. Time's up in here where name is equal to question mark and then name. I will actually, let's not do it here. Let's instead do it down here. Let me take this part and let me put it here where the ask from contacts. Let's first work on the rose and then we will take it back to the from contacts where name equals question mark n comment be here. This should be this. Yes. Let's right click and let's run the name that we're looking for is Michael. Hit Enter. All right, what do we have in here? Michael? Michael, everything is up but there's still a problem. The first loop worked. And actually maybe we should get rid of the first loop just so we know what is happening exactly in here. If I try Michael, boom, what is happening in here? Cult three, programming error, incorrect number of binding supplied. The current statement uses one and there are seven supplied. Is it telling us that we've supplied seven items in here? What do you think is the problem if you're not sure? Let's try another name. Let's hit Enter. It's telling us that we've provided five. What is happening? What's happening is that the parameters we're sending should be couples. When we did it right here, you can see that we provided the new e mail and the phone under the form of a couple. We've sent in a couple. What's happening here is when we're sending in the name, what it's doing is it's dissecting the name. We're getting K, L, E and we're getting five elements supplied. That's where the number five comes into play. And if we run and we provide it with Michael, Michael is 123,456.7 That's why it's telling us that we are providing seven. What's the solution in here? We add parentheses around the name with a comma, which makes it into a topple. Now if I write click and I run, and I type in hopes Michael hit Enter. There we go. I only get the information of Michael. And if I try to right click and run and try to get the information of Kalen. Boom, there we go. I also only get the information of Kalen. Of course, this could be applied right here in this format. If I remove this and I say in here space where the name is equal to this and then provided with on the name right click run in here, just Michael and I get the information for only Michael. Thanks so much for watching. I hope you enjoyed. But before we leave, there is a small hiccup here. That's why you always have to test your code. If I write, Click and I run and I type in Michael, I don't get anything. Hmm, that's not good at all. So what should we do in here? We should give you a challenge. Did you think that I would forget about giving you a challenge? No. What should we do? Look for how you can send in parameters to your SQL queries without worrying about the case. This is some research homework for you to do, test it out in our program. And I will give you a hint, but I do recommend that you go and try to do this yourself. Use the like instead of the equal. Pass the video right now and go do the challenge. Okay, welcome back in here, instead of using where name is equal to the peace holder, we'll use the like and we'll use the like. Now if I write click and I run and I type in Kalen without any upper case on the K and I hit Enter, I still get the correct information. Thank you so much for watching. I hope you enjoyed. In the next video, we're going to be looking at introduction to exceptions because we need to handle exceptions in case some errors come up. This is not just useful for SQL language, it's especially useful for SQL language, but it's useful for any field of Python that you're looking to learn through. I will see you in a few seconds. 147. 13. Introduction to Exceptions: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be looking at an introduction into exceptions. I think that this video is going to be exceptionally long because we have a lot of information to cover and this could have been a separate section on its own, but I decided to keep it in this section using databases in Python. It's very important that we learn this not just for database and SQL, but also for anywhere else that you might encounter this throughout your professional career. For this, we need to create a new project in here. And this project is of course going to be Python. And make sure to save it in the appropriate place. And I'm going to call this the exception handling. And finish up. Yes, this window. First of all, I'm going to create a new Python file and I'm going to call it the examples. Just a few examples where we're going to look at very surface level errors that can occur. And what happens? First of all, we're going to say x equals eight equals five. Now obviously this is something that by fund doesn't like. As you can see, even before we run, we already have this error right here. Test that you cannot assign this literal. If I try to write, click and Run, there we go. Syntax error cannot assign to a literal, meaning you cannot assign five to the number eight. You cannot do this. This can be saved by a simple correction where the student, or the user, or whatever just made a mistake and they were intending on writing eight minus five. Now, there we go. No more error. Of course, this is a very simple or surface level error that can happen. Let's look at something more serious. For example, if I do the following. If I say that I want y to be equal to x divided by zero. Now this is a different type of error where we don't have any indication with a red line. Before we saw that even before running the program, there was something wrong. Now, there's nothing wrong. But you should be aware that dividing by zero is a big no, no, we have an error specifically for that zero division error, division by zero. It's not possible. As you can see, the issue here is that sometimes we might get an indication, sometimes we might not get an indication. And we have many different types of errors. So I'm going to show you the following website, and of course I will provide it somewhere. If I don't, please contact me and let me know. So this is the built in exception in the Python documentations. You can go through this entire website, understand properly all the exceptions. So for example, except except buffering errors, these are how should I say it more in depth? Things like the buffering error and the lock up error. But still you can find any error that you want in here. If I do control andintype in zero division, there we go. So raised when the second argument of a division or modulo operation is zero, if I try to search for value. For example, value error. There are many iterations of this. There we go, raised when operation or function receives an argument that has the right type but an inappropriate value. There we go. As you can see, there are many different types of errors. You can go through all of them. Also, I recommend that you check out this website, so this is a more compact way because sometimes as you can see, the documentation can be very overwhelming. Like what do I need to look at right here? And by the way, the table is also very crucial to understand. You don't have to go through and remember every single one. But now at least you can go back to this website and see a few examples. Now right here, the Python built in exceptions are also very important. This is W three schools. It's one of my all time favorite. I've been using it since I think I was like 11 now. I'm much older than that. I've been using this for years, more than 15 years. Amazing website, highly recommended. They're not sponsoring me, although I would take their sponsorship and actually I would do it for free because they were incredible. Again, go through the exceptions, Look at what we have. For example, index error raised when the index of a sequence does not exist. They've created, compiled a very nice list in here and I recommend that you go through it. I will have the link somewhere around. But let's go ahead and try to create something called a recursion error. Meaning that when a function calls itself too much here, I'm going to do the following. I'm going to define a new function, which is going to be, actually I think. Let's comment these out. Let's define the function at the top. And we'll just have this, we'll have the count underscore down and we'll count until n. Then in here I will check if n is equal to zero, then I will print of last. Then I'm going to print out n. Then I will count down. I'm calling the same function, but this time n minus one. This is a recursive function, meaning that it calls itself, what does this happen, what does this do? I mean, if I print out countdown I provided with. Actually, we don't need to print. I apologize because we already have a print inside in here. I will do ten. If I write click and I run look at that, we have 109-876-8321, Blastoff. We have a blast off. This function can have its problems because if we do 100 and write, click and run, we do get a blast off. If we do 1,000 boom, you can see that we were able to get to five, and then suddenly we had a issue in here. And that issue was that we repeated 993 more times. The Python went into its maximum recursion depth. It was exceeded while calling or calling a Python object. This is another error that can come up. So how do we catch these errors and how do we make sure that they do not break our code? As you saw right here, we can do that using exceptions and try and get exception. Exceptions are objects that are created when an error or exceptional condition occurs. Just like we saw right now, what you're seeing are objects being created. Just like I told you, everything in Python is an object. Almost some built in exceptions in Python are value error, type error, file not found, error, and the zero division error. These are just a few examples. Accept is a statement that allows you to handle these errors and I'm going to show you how it works. The tri block contains the code that you want to try to execute. The accept block contains the code that you execute if an error occurs in the tri block. So the final block contains the code that you execute. The final block contains the code that you will execute regardless of whether or not an error occurs in your tri block. And we're going to look at the final block later on, but for now we're going to work on the tri except blocks. In the next video, we will look at the final block. Let's see how we can use this tri except block to make sure that we don't get the recursion error back in here where we call our function. So this is the code that we are trying to run. What I'll do, and you've probably seen this before, we are going to try the code, then we're going to do an exception in case we have a recurs or recursion error. We're going to print out the counts are too many. What should we call the counts are too many. Then in here we will print out program program terminated. If I write click and I run, look at that. Instead of getting an error and having our code stop or break. Instead we have the counts are too many and that the program is terminated. And I added the sprint just to show you that we actually were able to continue down the lines of our code. And this is great, especially on the user side, it's usually better to be explicit when presenting the potential exemption that would occur. But sometimes you might not know what the error could be. So right now, sure, we know that this is a recursion error because we've tested it out. And we know that we called the count down too many times, but what if? We had a small potential error inside. And obviously, again, I want you to take this with a grain of salt. And here, of course, this would not happen. But what if it did? What if we were trying to divide this by zero? Now if I write Click and I run, you'll see that our code breaks again. And why is that? It's because we were simply trying to catch the recursion error and not the zero division error. To fix this, we can do the following. I can say except zero division error, then print out. You cannot divide by zero. And I write divide incorrectly, divide yes. Now if I right click run. There we go. You cannot divide by zero. That's great. We've got the second error. But there is a more efficient way of doing this. Instead of having two different exceptions, we can create something like this, zero division error. Close this down, and we can simply comment this one out. So in here, the counts are too many or you divided by zero, okay? So this allows you to, of course, this is not as specific as we had before, but this can help you raise an exception in case you have just a general error catcher. And you don't want to use multiple lines to catch very specific errors unless you have, for example, different types of codes that you want to execute. Not just a print in case you have a zero division or in case you have a recursion error. But in situations like these where you just have a print, you're just printing something to the screen, it's not as important. For example, when you're entering your E mail and you type in your username and then you type in your password and it's not right, one of them is incorrect. When you hit enter, they don't specify, for example, that your password is wrong or that your username is wrong. They tell you either your username or your password are written incorrectly. In that case, you have something like this situation. Okay, I hope that is understood. Now let's go ahead and try creating a program that would have a lot of potential errors for us and create the necessary exceptions for that. I'm going to go into file new and create a new Python file that we're going to call operations bull and close the examples down. And I should have had added an underscore between the catching operations, but that's okay for now. We'll have number one equals flowed input the first number. Duplicate this number two flow, enter the second number, then I'm going to have result equals number one divided by number two. I will print out the result is two dots result. Okay, there we go. Before we even launch, you probably know that there could be a lot of potential issues in here. Like for example, having number two being zero. This is just off the top of my head. Now what I want to do is I want to issue you a challenge to catch them all like Pokemon. Get a catch them all. First of all, catch all the possible errors that might occur. I want you to take the time to think about them, because there should be at least two. The important part is knowing where the Troy block starts and where the exception block should be added. I don't want you to go too in depth and think of all the possibilities. Just think of two, at least. The main important thing I want you to do in here is to know where to add the block. And I'll give you a bit of a hint, you should have value error and zero error division. These are the two or the first two. I want you to think of a third one. Buzz the video right now. Sorry, I forgot to give you a few seconds before showing you the hint. I just thought that these are very new things. Maybe you're still overwhelmed. Buzz the video right now and go do the challenge. Okay, how did you get on with that first? Or we need to create the tri block for the value error. I'm going to tab this. I'm going to add the tri block right here at the top because this is where the errors would start here. Or after we try to print out the results, I'm going to create the accept. We are going to have a value error. I'm going to put in here. You need to be inputting some, you need to add an actual number in here. If you went through and you read about value error, you should know that if we, for example, try to just hit Enter on the first number, we get an error that you need to add an actual number in here. You can't just have a. If we didn't have, I should have tried this before. Actually, let's just copy the code and add it right here. I will right click and I will run. And I will just hit Enter. And there we go. You can see that we get a value error and our code breaks. This is the first thing that we need to watch out for. The second thing, or the second exception should be the zero division, because we've already seen it before. I'm going to print out who the heck still divides by zero, Go back to school. Right click, run first number 12, second number zero, the heck still divides by zero, go back to school. Now, in all fairness, we should at least indicate that we are going to be dividing number one by two so that the person knows that they cannot enter a two. But that's beside the point. We've got the zero division. The last exception we can think of is an overflow where the number is just two big. I'm going to add an extra one in here, an extra line. I'm going to say that the result is equal to result multiplied by not multiplied to the power of 1,000 I don't know if that's enough. Let's try 10,000 Right click, run 12 to boom. There we go. An overflow 34 result is just too large. How do we handle this? Well, here we say, except overflow error and we'll just say number is too big to represent. All right, click run 125, sorry, number is too big to represent 2.4 Where did we get that? Oh, it's the normal result that we have in here. And then the result of the multiplication was 2.4 Now, you might be thinking, wait, Michael, you cheated. You cheated. I saw you, you cheated because you added an extra line of code. How could I have known that this is an overflow error? Well, even if I removed this, and I know this is going to be hard. But for example, if I type in, let's say just one, I type in 0.0 0000 0000 0000 0000. A few 0.1 okay? That still works. I mean, if you type in enough zeros at some point, the number is going to be too big. Let me try and actually do this. Let me run. I don't know, even if I will get okay, that still works. I think we need a lot more. And at this point, I want to thank you so much for watching. I hope you enjoy it, and I will see you in the next video. But if you're interested in this experiment, let's test it out. Uh huh. Who? Oh, oh, oh, okay. So it considered it as zero before we had an overflow. Okay. You can say, Michael, I cheated. I did cheat. So what can you do about it? Thanks so much for watching. I hope you enjoyed sorry for the very, very long video, but I believe this wasn't a too hard of a video to think about. That's why I kept it as big. There were no very tiresome things to think about. So in the next video, we're going to be looking at the finally block and how it works and how it can be very useful. Thanks so much for watching. I will see you in a few seconds. Bye bye for now. 148. 14. Finally block in Exceptions: Welcome back my fellow Python exceptists. Let's continue on working with exceptions and we're going to be looking at finally blocks and a few extra things in here. First of all, let's say we want to have a general exception, we're not sure what it is, we just want to catch some kind of exception. We can do the following. We can then, as then in here, I can print out unexpected error, expected error, two dots. Yeah, there we go. The warning is gone. If I right click and I run and I don't provide a number, you need to add an actual number in here. As you can see, we went down through this list and we actually caught it at this point. Let me, for example, show you if I remove this overflow error and I turn this back on right click, and let's say 125 result, Unexpected error. And I get the result is too large. As you can see, just in case we want to catch general things, we're not sure what they will be, We just say unexpected error and do the following. Now let's look also at the finally block. Finally, if I type it in and print out this finally block will execute less of just regardless. If in here I let me remove this right click and run. And if I type and 125, hit Enter, there we go. This finally block executes regardless, we don't get any errors. If I take this back on right click 125 again, we get an error. We handled it, but the finally block executes regardless, the final block will execute whether there is an exception raised or not. It is used to maybe used for clean up options such as closing a file or closing a database. And we'll be using the finally block a lot. And you'll see a lot of use cases for it later on. Now we also have the L in here. If we test it out, you can see that for some reason we can't have the finally, it needs to be below the exceptions. And before the finally in here I will add an L L. We could say, for example, division was successful two. Let's comment this one out because it always causes an error. If I write the click and I run 125, boom, 2.4 division was successful, typically used, or the else clause is called when there are no errors getting caught. This can be useful in situations where you want to ensure that if the code correctly you provide something. Meaning that some code in case everything goes smoothly. One last thing before we move on to raising our own exceptions is that the order of the exceptions is also very important. Catching more specific exceptions before catching the more general one is better. The reason for this is that if a specific exception is caught before a more general one, the program can take appropriate action to resolve the exceptions and prevent more severe consequences. For example, if let's say move this hold down control shift. Or hold down shift down, shift alt, shift alt. And I move it right here to the top. You'll see that I first of all have exception supercluster, exception has already been cut, see that? So right click and run, and if I just hit Enter, Unexpected error could not convert string to float even though the issue here wasn't that we weren't able to convert a string to a float. The problem in here was that we just did not provide a number. So we have to be more specific. The more specific we are at the beginning, the better the results are going to be. So thank you so much for watching. I hope you enjoyed. And in the next video, we'll be raising our own exceptions. We'll see how we can create or use these exceptions in a more real world situational way, where we will be creating a bank account, which is going to be very fun. Thank you for watching. I will see you in the next video. And no, there are no challenges in this one. 149. 15. Raising Exceptions: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be raising exceptions. First thing we're going to do is we are going to create a new Python file that we are going to call bank account. You think I would come up with a shorter, more eloquent name. But as I'm just a humble Python instructor, not a name come upper that came out back as you can see, class bank account. We're creating a new class. We're going to define the Init, which is going to take in the underscore balance inside. We're going to set the self balance equal, equal to the initial balance. Then we're going to define the deposit inside. We're going to, of course, have the self, it's already written, and the amount that we would like to deposit. Then we're going to say that the self balance plus equals the amount. Then we're going to define the withdrawal with draw. Then we're going to also have an amount in here. Of course, that amount is going to be taken out of the balance minus equal amount. We're also going to have the show Underscore balance. And here we're going to return return self balance. Okay, there we go. This is our class. And actually I'll just remove this extra space in here. And now we can work on the body of our code. So I'm going to create the bank underscore account one. And it's going to be equal to the bank account and I'm just going to deposit 200 inside. Then I'm going to take the bank account one, deposit 120, then I'm going to withdraw, uh, 20 and then I'm going to take my bank account and then show the balance just so we can see. So we should have 200 plus 120. 320 -20 We should have just 300. So when we run nice, we don't get anything. Oh, I apologize. We need to actually put it in a print. There we go. And now this should come out as 300. Excellent. So we have everything working in there. But there are a lot of problems with this code. For example, we can create a bank account with a negative initial balance. So for example, if I do bank account two equal to bank account, and I can start with a negative balance. So I actually open a bank account and I owe them money already. So if I print out bank account two, Dutch balance, yeah, it's not going to look very nice. Because I have -300 and let's make it minus 22. There we go. So let me know what we're working with. This is a negative initial balance, Not very good. The other issue is that I can actually deposit and withdraw negative amounts, which is even worse in here. For example, I will create bank account, bank account three. And I will say that it's equal to the bank account and I will deposit 200. And then I will say bank account deposit deposit -30 And I will print out bank account three, show balance and then write click and run and look at that I've actually deposited negative amounts which means that I withdrew money, but I did not call the withdrawal, which is very bad. And I can also withdraw negative money. So I can do the following, bank account three withdraw and I can actually withdraw -20 which means I will add 20. So I'm using the withdrawal to add money and I'm using the deposit to take money out. All of this is extremely, extremely bad and we can also withdraw more than we actually have. So all of these are problems that we have to somehow look after. Bank account four equals to bank account and I will just deposit in here like 100. And then I will do bank account four, withdraw. And I will withdraw 300. And then print out bank account four, show balance. So now I have -200 All of these are very huge issues that we need to find a way to get rid of, or at least terminate the program before they actually work. And of course, I know what you're saying, like obviously we've created more eloquent, better bank accounts before that would handle all of these situations. But for now, I just want to show you how we can raise exceptions in order to counteract this. So what is raising exceptions? So we've seen how sometimes if we use unorthodox methods, like unorthodox, unorthodox methods, that's putting it lightly, meaning that when you try to divide by zero, for example, a error gets raised. The same thing should happen in here. For example, before we set the balance, I want to check if the initial balance is less than zero, we're going to raise value error. And I'm going to say in here that the initial balance cannot be negative. Now if I tried to run this before we do this, before we actually try to do this, we need to of course, add and accept blocks. That is going to be a challenge for you to get it our new bank account, add accept block to our code. But that's not the only thing that you need to do because you need to add the other exceptions that need to be raised in cases like the deposit amount is negative, the withdrawal amount is positive, and the amount of withdrawal was more than the available amount. And finally, these all should be done inside of the methods of our class. And of course, along with these raised exceptions, you should add the try except block for every single one. So pass the video right now and go do the challenge A. Okay, welcome back. How do you get on with that? First of all, we need to add except block four when adding the initial balance. And of course, we should add this to every single one, But because I've created four different bank accounts, each one with their own issue, that is why I'm only going to add this to this one. And what we're trying is to add a negative amount in here. I will have an accept value error because we know it's a value error. And I'm going to print value error as sorry as print out. There we go. What's the issue in here? Bank account can be undefined. Undefined, we are, we're trying, this line might not execute, this might not be defined. What I'll do is I'll move this right here. Inside of the block. We will try to create the bank account and to show the balance when I write, click and boom, there we go. Initial balance cannot be negative, the bank account two did not execute and did not work, but we did not break our program. That's good. Next we need to work on the deposit. Let me move this to the side because we have a lot of horizontal space in here. And the deposit, first of all, we will want to check, if the amount is less than zero, then I'm going to raise another value error which is going to tell us that deposit deposit amount cannot be negative. Oh my God, why can't I write deposit amount cannot be negative? Where do we add the tri block? Right here. We need to try this deposit and raise an exception or just I mean catch the exception in here and print out. When I write the click and I run, the initial balance cannot be negative and the deposit amount cannot be negative. We've got two errors so far, that's very good. Unfortunately, there are a few things that we also need to do which is the withdrawal in here. On the withdrawal, there are actually two things that we need to do. There is making sure that the amount is less than zero and also making sure that the amount is greater than the self balance. And what I mean by that is, first of all, I want to check if the amount is less than zero, then I'm going to raise a value error. I want to say that withdrawal amount cannot be negative and I'm going to check if the amount is greater than the self dot balance. I'm going to also raise a value error telling me that in sufficient funds, insufficient. Is that how you write insufficient? I have no idea. Insuficienthh. Okay. I forgot the. All right, so there we go. Now, where should I add this? Well, I should try this one. It inside of the accept, let me add a space, add a tab, remove this, accept the value error as print out. Now when I write, click and I run, boom, Withdrawal amount cannot be negative. I also got an error for the insufficient funds. Let's go ahead and try and catch these as well. Where did we do it? Right here. Right here. We're going to try except value error as print right click, run, and there we go. We have insufficient funds. Ladies and gentlemen, this is all. Thank you so much for watching. I hope you enjoy it. I hope you understood how raising exceptions can be very helpful. In the next video, we're actually going to be creating our own exceptions. Is that I will see you in the next video. Bye bye for now. 150. 16. Creating your own Exceptions: Welcome back my favorite python programmers to a brand new video. And in this one, first of all, we're going to do a bit of cleaning up, where I will show you how to make this code more efficient and look better. And then we are going to be creating our own exceptions, so our own errors. How cool is that? So let's go ahead and get started. First of all, as you can see, this is not very feasible. Trying to create a try and accept at every single point. Not really good, not really efficient. We want a better way. And that way is to do the tri accept block inside of our actual definitions of methods. For example, instead of creating the tri accept block right here on the bank account object instance, we are going to create it inside of the It or inside of the constructor. Inside of the constructor, I'm going to create the try and then I'm going to tab this forward and then I will create an accept, and then we'll have a value error as I will just copy. We're, we're printing the print. I will say error. Boom. Replacement field E. There we go. Now we can shift this, Remove the accept, the try, and if I right click on I should see, there we go, that we have an arrow bank account object has no attribute balance. What is the issue in here? At the time, no. So the problem in here is that we got a second error. And where did that error come from? Well, it came from, so here we have an E. Okay, Don't worry, this is a shadow name because we've used the E here and here. And don't worry, this will go away later. The issue in here is that we tried this code, but because it's a negative balance, we haven't created self balance. And that's correct, that's exactly what we want. But the problem is when we tried to show the balance or I mean return the balance which was in the show balance. If you follow the error, you'll find that we don't have a balance or self thought balance anyway. So how do we handle that? Well, we have to handle it inside of the show balance in here. We are going to create a try and we're going to try if has attribute. This allows us to check if we have an attribute on the self because we're referencing ourselves and we are checking for balance. So this is a string object, You can even hover over the attribute, and you can see that, first of all, we provide the object where we want to check if they have that attribute and the string which is going to be the name of that attribute, so it's the self, which is our own object. And then the balance name, or the attribute name, which is balance. And if we do have that attribute, then we will return balance. And then else what shall we return? We're going to raise a error in here which is going to be the attribute error. And we actually have something called the attribute error. And we're going to say that this bank account has no balance, boom. And then we are going to do the accept attribute error as E and print out error E. Okay? So there we go. Now if we right click and we run, we shouldn't get this error again. We should get initial balance cannot be negative. This is from right here. And you can see this error. And then this bank account has no balance. And also it I recommend that you, if you remember from the function section that we did, one of the last sessions was when we used color in here. I recommend that you also use color. Make it bold, make it very obvious that there are errors here. But that's for a static reasons for style, I'm not going to delve into it. The main important thing in here is that we were able to fix this issue. You'll notice that we are printing none because we don't have a bank account, I believe because we've put it in a variable and tried to print it out. Is this the line? Let me check bank balance. Let's just make sure where this none is coming from. Yes, it was indeed coming from this print. Because we're trying to print something and it's just coming out as non. I hope that was understood and wasn't too complicated. The main important thing and the very new thing that we learned is the has attribute that we have right here. So let's continue on and now let's look at fixing the withdrawal. Instead of doing the try and accept right here or first we'll work on the deposit. I think instead of doing the try and catching the error right here, we're going to do it instead inside of the deposit in here. We're going to try this first we'll, if amount is less than zero, then we're going to raise the value error. And then we're going to accept value error. Value error as boom. And then I'll just copy this line. Put it here. There we go. Now if we write, Click and we run the error deposit amount cannot be negative. Perfect. It's working exactly as intended. Let's do the withdrawal. So the same thing holds true in here. We're going to do a column tab except value error as I can just copy this and paste it in here. It's just the same. I will remove the tri except in the body of our code. And we should have all of the errors now done, right? Yeah, there we go. Error. Insufficient funds. Excellent. Everything seems to be working completely fine. We were not able to withdraw more money that we have, and we were not able to withdraw negative amounts. Perfect. So we fixed everything. And the body of our code is much more reliable, much more dynamic. We don't have to write every single try and accept block for every single transaction that we make. It's much better to do these inside of our classes and inside of the methods of our classes. Okay, so I hope that was understood. Now it's time to start creating our own exceptions. I'm going to create a new Python file in here, a new Python file, and I'm going to call it creating exceptions. Exceptions. And let's actually add an underscore just in case we want to use it somewhere else. In here, I'm going to create a class which is going to be invalid transactions or transaction this class is going to inherit from exception exception. If we hold control and we go to exception, you'll see that it's a, it's a common base class for all non exit exceptions. We can see that we can initialize it right here, we have some static methods, we can do a few things with this exception. Mainly you can obviously go and read all about this exception class in much more detail if you go to the Python documentation. But for now we're just going to use it on the surface level, I'm going to define the It in here inside of the it we are going to be sending in the message. Then I'll have the self dot a message equal to the message. And I will do a super because I want to call the top level super in it and then Seselft message. Obviously you can create much more intricate classes of these invalid transaction errors. But for now we're just going to keep it very simple. I'm going to create a class bank account the same that we had before, but a little bit simpler. So I'm going to define the It with an initial balance balance, okay? I forgot the here. And then I'm going to say solve balance equals initial balance. And then I'm going to define the deposit. And we'll have an amount in here. I'm going to do two things. I'm going first of all, to try and check if the amount is less than zero, which is something that we've done before. I'm going to when am I going to raise the invalid transaction error. And what's wrong with deposit? Deposit may be static. Okay. No worries about that in here. And I'm going to send in the message deposit. The Posit amount amount cannot be negative. We are going to also in here say that self lot balance plus equals amount and I'm going to catch the exception, invalid transaction error as E and print out error to dots replacement field. There we go. Then I'm going to define the withdrawal withdrawal. Of course, we'll have the self and the amount. And we're going to check for two things in here. Actually, let me just copy this code and modify it. Boom. In here, K value error instead of value error, we're going to have the invalid tactvalidvalid transaction. We should be done with this. Let's, I think all of these are well created. Now, before we continue on, I do have a challenge for you to create an exception. So I want you to create an exception for the negative initial balance. And I want you to use it, because keep in mind we haven't created it yet. To create your own exception, it's basically like creating a class that inherits from exception. We've already covered that. But I just wanted to give you some extra hints because this is something new. So your definition should be class negative, initial balance, error, exception, and right here, exception, meaning that it inherits from the exception based class. It needs to have a constructor that takes in a message and sends it to the constructor of the exception class using the super. Pass the video right now and go create your own errors. Welcome back. How did you get on with that? Right here, two lines below, I'm going to create a class and I'm going to call it a negative initial balance error which inherits from exception. I will just have the same in it that I had in the invalid transaction error in here. I hope you tried to do this yourself even though it wasn't part of the challenge. But try and catch it right here. We're going to try to check. If the initial balance is less than zero, then I'm going to raise the negative initial balance, telling the user that balance cannot be negative. Oh my god. Let me check. Okay, so we will hit that because this should be part of the tri block we're trying to create the initial balance. And then we will do accept negative initial balance error as E and we will print out error. There we go. So this is our bank account. Let's try to create a bank account in here. Bank underscore account one equals to bank account -300 Right click. We should get the error. Initial balance cannot be negative. All right, let's make it normal. Do we get any errors? No, we don't. We don't have any printing. It's okay. No need for the show balance. You want the extra exercise? I do recommend that you create the show balance with its own error or exception that you can raise in case somebody doesn't have the attribute bank account one, bank account 300. Let's now try to deposit some negative money. -30 Right click run. We should get deposit amount cannot be negative. Very nice. Let's try to withdraw negative amounts of money. Amounts of money cannot be negative. Withdrawal amount cannot be negative. Perfect. What else can we do? And by the way, like we can do something like this. Okay. It will not allow us. Let's try to just raise this so we can see our own error in play. Right click and run. Boom. There we go. Invalid transaction error. How cool is that? Withdrawal amount cannot be negative? There we go. You can see that we were able to raise our own. So thanks so much for watching. I hope you enjoyed. In the next video, we're going to be making our bank account much more sophisticated. So I will see you then where we will also be like we will start building a new project which is a bank account database. So it's going to become much more sophisticated. We're going to be using all of the things that we've done so far, including the exceptions, including the databases, including the classes. So this is going to be one of our biggest projects. So I will see you then. Bye bye for now. 151. 17. A More Sophisticated Bank Account: Welcome back my favorite python programmers to a brand new video. I think this one is going to be a short one. We're just going to be setting up our bank account database because this is going to be the start of, I don't know how big this project is going to be, but it's going to be a fairly big project. First of all, we're going to go into file new and we are going to create a new Python project next. And it's going to be called the bank account database book. Open project in this window. Yes. Then in here I'm going to create a new Python file which is going to be the bank accounts. There we go. Now we have a bank account class in here. I'm going to create class bank account. It's just going to inherit from object. Obviously we don't have to do this, but sometimes you get in the habit of doing things. I think it's a good habit to have. Then we are going to initialize it and this one is going to be much more complex than the other one. We're going to have deep annotation. The name is going to be an STR. The initial underscore balance is going to be of type float, and we're going to set it to be 0.0 We're going to give it a default value. Then we'll have self name equals name. And in here we need to add a space. Then we are going to have the Self Balance. And it's going to be equal to the initial balance. And I will print out the account created for replacement field self name. There we go. And we will also show the balance, but we still don't have that. So let's add a comment in here to show balance. Then we are going to define the deposit deposit. We're going to have the self and the amount which will be of type float. It will also return a float. We're going to add the arrow in here saying that it returns a float. And we'll check if the amount is greater than 0.0 we'll have balance plus equals the amount. We are going to print out replacement field amount deposited. We will return self balance. By the way, I want to make balance hidden, I will add an underscore behind balance from now on. It's better to have it hidden. Let's continue on and let's now work on the withdrawals. In here, I'm going to define the withdrawal again with the self, again with the amount which will be a F and it will return as well. And then in here I'm going to check if we have the amount between or greater than zero and less than or equal to self dot balance, then I will have the self dot balance minus equal the amount. I will print out replacement field amount. With draw, I will return the amount else I'm going to print out. Now in here, I was always thinking, should I create exceptions for this particular project? To be honest with you, I just felt like maybe right now it's not a good idea because we want to focus on the actual database handling of things. Later on, we will add exceptions to the withdrawal deposit. We will keep these simple. We will add try and accept blocks when we are working with executing database commands. It will be much more important there, but for now we'll just keep things simple. We'll just have conditions and we will work within the needed parameters. In here, we will say the amount must be greater than zero and shouldn't exceed, shouldn't we need to make it into a special character. Shouldn't exceed account balance And we will return 0.0 Finally, we are going to define show underscore balance. Let me close this one down so that you can have a better shouldn't. I think it's just so okay. No worries. So balance self. And we will simply print out in here, balance for account replacement. Field name is replacement field self Balance. There we go. This is our bank account we've covered, I think almost everything. Oh yeah, Yeah. There we go. In here, we just show balance self. So balance, This is when we create our bank account right here. Let's go ahead and test it out with a few lines, I'm going to create Michael. And it's going to be the bank account. The name is going to be Michael. No initial deposit. We're going to get Michael and deposit 10.5 Click and run. Let's see what we get as an answer account created for Michael Bank balance of account. It maybe should be Michael's account, I don't know. It is 0.0 10.5 deposited. So let's try to withdraw Michael Withdraw 2.5 Let's see what we get. Boom. Okay. 2.5 Withdrawn. Withdrawn. I think it should be withdrawn at that time. You write withdrawn. Yes. Okay. Withdrawn. Nice. Do we show the balance? I don't know if we should show the balance every single time we make a transaction. We'll see, we'll see how this progresses and we will work accordingly. Let's just do the show balance right now, manually. Right click and run. So is that correct, 10.5 -2.0 that is correct. Let's make another withdrawal of 2.8 Let's just see how accurate this is. Show balance, right click, run. There we go. 5.2 Thank you so much for watching. I hope you enjoyed. We're just setting things up because in the next video we're going to be adding database to our backcount class and start really putting all of these things into databases. And we're going to be working with a Database Explorer or a browser that will allow us to look through our database. It's going to be so, so much fun. So I will see you then. Bye bye from now. 152. 18. Adding a Database: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be adding a database to our bank account. First of all, we need to establish what we're going to be actually doing. We want to create a database for two things. We want to create a database for our accounts and a database for our transactions. So we're going to have two tables, and let me show you how these tables are going to look like. First of all, we're going to have the account table, which is going to be a very simple table. We'll just have the names, which is going to be PK. Now, what's a PK? Pk means primary key. And we've already seen what a primary key is before when we were working with the movie's database. Meaning that the primary key, well, is a key that is primary and it cannot be duplicated. The name is going to be a text and we want to make sure that it is not null. Then we have the balance which is going to be an integer and it also should be not null. Then we have the transaction table which is also going to have its own primary key which is going to be, which is going to be of type time stamp and it's also going to be not null. Now, time stamp is a value or has values that store data of time and of a certain event and they are automatically updated. And I will show you how all of that works. Actually, I'm not the one that's going to show you, you're going to be doing it in a challenge, but that's for a few minutes later. First of all, we need to also know that the account is also going to be a primary key. Yes. Every table can have multiple primary keys. It's going to be a text and it's going to be not null. And finally, we will have the amount which is going to be an integer and it also should be not. Let's now look at a challenge that you will have to do. You'll need to create two tables, just like we've done before where we imported Esqulite, created the connection, etcetera, et cetera. You will have to do the same inside of the bank account class file or what was it called? Let me just check. Yes, bank account class. First you need to establish a connection. Use the connection to execute queries. Make sure that the tables don't exist already and we've seen what that is. And set the primary key and make sure that the fields are not not now. If you're uncertain of how to do this, this is the perfect opportunity for you to go and research how to do this stuff. Please take your time, do your best. There's no rush, but it's very important that you start doing things on your own, especially at this point. We, of course, this class or master class will always be updated, but we are almost at the end of the usual or normal one. So please take your time. Go try to do your best. And I will see you a few seconds. Welcome back. How did you get on with that? First of all, right, here at the top, I'm going to import my Sqlite Three. Then in here I'm going to create the connection. I will say B, we can call it connection, we can call DB. It depends on what you want to do. Sqlite three connect and we're going to connect to Accounts Light, there we go. We will create a new file in here. I'm going to have the B execute. And we will want to create table, if not exists accounts inside of accounts. We're going to have the name which is going to be text and it's going to be primary key null. This is what we needed to write in order to create the name. And we're also going to have the balance which is an integer null. Now of course, there are flaws with this stable and this database, having a name as a primary key is not really good. Because imagine if two people called Michael wanted to open the account, it's better to have an ID that would automatically increment. But for now, we just want to keep things simple. So we'll just have the name, text, primary key. No, I'm going to duplicate this because I want to create a table. If not exists, but this time it's going to be that of transactions and we're going to have a few different things. Transactions. What did I write Incorrect. Okay? I add an extra in there. First of all we're going to have the time and it's going to be of type time stamp. I'm actually going to add or hit Enter in here to go to a second line. Then we're going to have the account which is going to be of type text, it will be not null. And finally we have the amount which is integer. Why can't I write today integer and it's going to be not null. Finally, we want to make sure that we have these two primary keys. Now in here, we don't need to specify that this is a primary key, because we will have two primary keys. What we can do is we can write it this way key. The, oops, come on account. We could have set primary key here and primary key here. But we can also do it this way if table not exists. Transactions time, time time null, account text null amount, integer, okay, looks good. And we have the class right here. Now we're going to make a few changes to our constructor so that it retrieve information from the database and fills data as well. If the data is not in the table, we're going to create one and add it to our table. Right here in the T, I'm going to create a cursor object. In here I will have the cover. And it's going to be equal to b execute. And I'm going to have select name balance from counts where name equals placeholder. And let's add spaces in here. Remember, because we've already talked about this, these should be topples in here. We'll have row equals cursor, fetch one. Then we're going to check row. Meaning if we have anything inside of row and it's not just an empty, then we're going to say self name. Self underscore balance is equal to row and we will print out account record. Retrieved. Is that how you write Retrieved guys? I'm a Python instructor. I have no retrieved. Yeah, there we go. I'm very bad at English, so four self. There we go. This should be good else, meaning that we don't have any roles. We are going to create that role. But before we actually say that we've created it, we want to actually execute it or insert it into our table cursor. We are going to insert into accounts values in here it. And the values will be placeholders. And then we're going to have name, initial balance. And of course, we need to commit these changes. Cursor commit or connection commit. Boom, there we go. And something to keep in mind. You might think that I just printed out account created by convenient ways. I put it right here under the insert. But it's actually very important that we as print out that the account was created for name after we make sure that we've committed our changes. Because sometimes you might run the program or do something and the connection with the database did not commit and then you print out account was created when in fact it hasn't. So it's very important that we do this. And actually in here, the last thing I want to do, maybe we can just show balance anyways. I don't think so. I think we should only do it in case. But you know what? The only issue is that sometimes I think we should show balance anyways. Because if we retrieve a value, we would like to show the balance if we haven't retrieved a value and created one. Instead, we also want to show balance. So the show balance should be on the outside. So as you can see, let's try to run this program, write a click and run. We should get the following bank account balance balance balance, 5.0 Okay, there we go. So account created for Michael. This was the first run. Let's now try to write the click and run and we should get account record retrieved for. And let's hope this works. Yes. Nice. As you can see, the account record now was retrieved for Michael. It wasn't created for Michael, it was retrieved. If we go in the accounts esculite right here into our project files, we can see that account Este was created. Before we move on, let's create a few more bank accounts in here. I'm going to duplicate this twice and I'm going to Kalos bank account are obviously going to be Al Thomas capital K capital. Let's also create one for Mark. I want to have many accounts mark 500. Let's give Galen 35400 at the end. We always need to make sure to b close, let's write, Click and run. And we should see that we get three accounts created, account retrieved for Michael, then account created for Kalen, then account created for Thomas as well. If you write, click and we run again. Boom, there we go. You can see that balance for Michael is zero. This is because we haven't provided anything. And then the accounts for Thomas and Kalen in fact, retrieved. Before we move on, there is something very important that I want you to do that is go to this website and download the database browser for Su. This will allow us to look through the database that we've created. Let me show you how this works. Once you've downloaded it, it's very simple. Just scroll down or just click on download. Find which version you need to download. It's very simple. You should have something looking like this. This is the database browser. Then I want you to go into Skylight. Let's try dragging it directly. Let's putting it right here. If I drag it directly, I don't think it works. Yes, no database file opened. Okay, no problem. Right click and open with Explorer. We should have opened it right here. Okay, there we go. Now, from here, I think we can drag it. Yeah, there we go. So as you can see, we have two tables. We can even see how these were created. Let me just set things up. So right here we can see that we have accounts, the name and the balance text. Null integer not null. We can even see that it's a primary key by the small gold key next to the name under the transactions. We also have time account and integer. And we can even browse the data. So you can see right here on the accounts we have Michael with zero, Kalen with 350, Thomas with 400, and Mark with 500. And if we go to the transactions, we don't have anything yet. But we will soon enough please download the database browser. You can even look through the database that I've provided you, the movies one, it's going to be very, very nice. You can go through, see all the actors, see everything. And you might be thinking like, why didn't you show me this before? Like I've been wasting my time doing select and whatever. Because I want you to get in the habit of finding things without the database browser. This is a crutch. This is not something should be taught or should be shown at the beginning, in my opinion. This should be later on when you already know how to retrieve data using just QL command lines. When you can do that confidently, you get to enjoy the ease of the database browser. I hope you enjoy it. I hope you understood, and I will see you in the next video, where we will actually be updating and inserting inside of our withdrawals and deposits. So I will see you then. Bye bye for now. 153. 19. INSERT Withdrawals and Deposits: Welcome back my favorite python programmers to a brand new video. And in this one we're going to be updating and inserting withdrawals and deposits into our database. I hope you downloaded the database browser because it's going to be, or it's going to come in very handy as we progress through this. So first of all, we need to make sure that we do everything properly, Meaning that whenever we make a deposit or whenever we make a withdrawal, that it's added to the balance of our accounts. So let's go ahead and get started with that. First of all, inside of the deposit, after we check that the amount is greater than zero and we are going to create a new balance which is going to be new underscore balance is going to be equal to self, but balance plus the amount. This one right here, I'm just going to remove it because we're going to be creating completely different code. This one we're going to keep, but we're going to be writing new code and you'll see the justification for creating a new variable. And just a bit, first of all, we need to set the deposit time. We're going to create deposit underscore time and it will be equal to pytZutclocalize. Then we'll have datetime time utc now. Date time time utc now. And we've seen this before in our oop, or object oriented programming section. I hope that you're familiar with what's happening in here. Even if we didn't go too much in depth into this, you should be familiar that this just returns our current time. Then we're going to do DB Execute, and inside I'm going to update Accounts, set balance placeholder, where the name equals a placeholder. And we're going to be replacing these with the new balance. The balance will be the new balance. That's why we created a variable forward and self name for the name of the account. Then we're going to also do insert into transactions. Insert into transactions values. And the values will be three placeholders. And then we will have the deposit time, self dot name and the amount that we had. And finally we will commit bit. After we've committed and we make sure that the database was updated, we're going to then update the balance in our object. Finally, we will print out that we've actually made the deposit. And I actually can separate these so that we have a clear distinction between where we are working on the database, on this part. Actually it's just these three lines. But you know what, actually we can separate these. This is where we work on the database, this is where we just set some variables up, and this is where we work on the actual object. So there we go. So in here, we create a new variable, which is going to be the new balance, because we want to use it right here to update the balance of the database of that account. We deposit the time, and we do the execution, we update the balance because remember we already have these accounts present. You cannot deposit to an account that's not there, that's why we are updating the account. But when it comes to inserting or when it comes to the transactions, we need to insert and not update. In fact, we cannot update transactions. That wouldn't be right. We don't want to be able to change transactions up. As you can see, everything in here makes sense. But there is something that we can do in order to alleviate the pain of looking at this line the whole time. And we've done it before because we're going to be updating the time the same way always. It's a good idea to create a static method. Right here at the top, I'm going to create a static static method. And it's going to be the underscore, get underscore current, underscore time. You've already seen this before, so I'm going to be returning, where is it, Bo. This line, we're going to be returning this, but we're also going to add with the IS time zone, which if you have or over it doesn't provide you with anything. It will just take me back to my current time zone which is not a good idea because you will know my approximate location. But that's okay. I have guns I'm in are we're going to have the bank account get current time and it will provide us with the current time. Now that we've done this, if for example, right click and I run, let's see, no such table as account. What are we doing in here? Wrong? New balance account. So let's see, in here should be account. Right click and run. Boom, There we go, through the balance in account eight. Let's look at our transactions. If I refresh look at that, how cool is that? Actually, we actually have a date. We have the account Michael and we have the amount 10.5 Why? Because we've deposited 10.5 Let's try and maybe duplicate this and maybe make this, I don't know, 6.5 or 6.3 right click run. And now if we look back at our database, we'll see when we refresh that we also have 10.5 Now this should be obvious to you, it's because we are constantly updating our account. And you'll also notice that Michael's account has actually grown. Why? Because we're committing these changes and because they are on top of each other, they are building up. So now our data is actually being saved. But as you can see, if we run this again, we are going to get another 10.5 and another 6.3. There we go. So these are our transactions. Well, we are finally working with databases, so our actions actually have consequences. But before we continue on and look at this deeper, we need to set up the withdrawal as well. And it's going to be a challenge for you. So your challenge is to, just as we updated the deposits, you need to update the same or need to do the same for the withdrawals in the withdrawal method. Make sure that you make the appropriate changes. There is only one small change that you need to make, so we'll need to find it, post the video right now, and go do the challenge. Welcome back. How did you get on with that? First of all, we make sure that the amount is less than the self balance and greater than zero then, just like we did before, we're going to say that the new balance, actually, I'm going to cheat and I'm going to copy all of this. How about that boom? Because it's almost identical, but there are a few changes. First of all, obviously the new balance is going to be minus the amount. The deposit time is going to stay the same. Bank account do get current time, this is not going to change. We are going to be updating the accounts and we're setting the balance where the name, it's all the same to the new balance and the set name, this line does not change. Next we have the Db dot execute. We're going to insert into transactions values the deposit time set name, but this time the amount is going to be negative because we are withdrawing. And then finally we're going to of course be committing the changes and we're going to be setting the albot balance to the new balance. And this line is no longer needed. As you can see, it is basically the same. And we're going to take advantage of that in just a bit. But for now, let's just list out what we've done, right? Click and run. So we've made a few withdrawals. If we write, Click in here and we look, boom, there we go, 2.5 and 2.8 withdrawn. And you can see that our values are starting to get a bit murky. The reason for this is because we're having small floating numbers changing, and that can sometimes cause Python to start making mistakes. We're going to figure this problem out. Maybe we can just show like two numbers or just one number after the decimal, even though it's not a great fix. But in order to fix this, it's a meticulous task. I'm going to try and find an easier one. I haven't done so so far. So that's why I'm going to keep things the way they are. But somewhere down the line when I update this course, I will make sure to get rid of this issue in the most simple way possible. With that, out of the way, there is something that we need to look at right here. You might have noticed that we actually have duplicate code. We have the same exact code with only small changes. What should we do when we have that? We need to extrapolate this information into a function. I'm going to create a new function in here which is going to be right under the in it. It's going to be. Right here. Define underscore, save, underscore update. And we're going to have self and the amount sent in. I'm actually going to base this right here. We're going to create the new balance which will be the self balance plus the amount you'll see when it comes to the withdrawal, we're going to be sending in the negative amount which will translate into a minus amount right here, which is going to work. And the code in here will stay exactly the same inside of the deposit. Instead of writing all of this, we can simply do self save, update and send in the amount. And do the same. All right here, update the amount. But what do we do in here? We send in a negative amount, so the only difference is going to be the use of minus one. And before we test things out, I want to take back the balances of our accounts to zero. Michael right now has 55.6 You can see that it's reflected correctly in the database. Okay. So in the database we don't have any issues, which is actually the most important part where we do have issues is in the display of Python. I don't think that's a huge problem, to be honest with you right here. All that we need to do is just type in zero and we need to make sure to write the changes. If I write click and I run, you'll see that the balance goes back to zero. Now, unfortunately I forgot Actually, let's go to account. As you can see, 11.5 it is accurate in the transactions, we still have these. What we can do is we can select all of these and delete. Wait. Select all of these and delete, There we go. Write the changes back in the account, set this to zero, write the changes. Now when I write click and I run, I should see officially we Michael has zero, okay? No problem. We should see in the transactions, 10.5 deposited, 6.3 deposited, 2.5 withdrawn, and 2.8 withdrawn. If I go to the transactions, there we go. We have everything represented accurately. So I hope you're enjoying what you're seeing. We are actually doing very advanced stuff, so you'll probably be facing similar things when you are working with a computer or real Python developing environment. In your work, of course, it will be much more complicated with its own intricacies, but this is the basics of it. You have objects, you have databases. You are updating things here and there, everything is working together. In the next video, we're going to be looking at rolling back transactions and seeing what would happen if we have some kind of issue when we're doing our updates. So I will see you in the next video. Bye bye for now. 154. 20. Rolling Back In SQL: Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be trying to break our database to see what happens and looking at rolling back transactions in databases. So let's go ahead and get started. First of all, we're going to delete everything in our database to start from scratch. So I'm going to select all the transactions and delete them. Make sure to write the changes and the accounts also select everyone and delete that and write the changes. So we're going to start simulating all things that can go wrong as we are saving our database. So the first thing we need to understand is that we have primary keys. And the primary keys should be unique. Our primary key is a combination of time and account. When we are working with transactions, this must always be unique. Let's try making our primary keys not unique. And the easiest way to do this is by simply changing the time that we have. For example, in here we have return YZ, whatever. This is always going to be unique. I will duplicate it and I'm going to change it to one. And I will comment this one out. So now we are going to get multiple ones. So I'm going to run my database and you'll see that we have an issue. We made the deposit and that worked. But when we tried to make wait, wait. Let me check. When we tried to make another deposit, we got an error. And that error was integrity error, where the unique constraint failed transaction time and the transaction account were the same. If we go back into our database and we refresh the data right here, you can see that we have Michael 10.5 and it worked. So the deposit worked. We committed the changes. If we look at the transactions, we do have one deposit, but you can see that the time is one. And when we tried to make a second deposit, that did not work because there was a time with one in there. In order to avoid having this issue, we need to create a Tri except block inside of our safe update. Right here we have new balance plus amount. We need to add a tri block on the execute because it was a matter of unique key integrity. We're going to try this and before we commit, we are going to try and catch an exception which will be esculite three error. Just any error that can come up from the esculite three. And if we do have an error we're going to get DB roll back. Then finally we will commit. What is the dot rollback? First of all, now we are going to execute the code and if there's an exception that is raised, we're going to do this rollback and we will always commit. But let's understand why we always commit, because we're doing a rollback. So what is the rollback? If I hover over it, do we get any information? Rollback, The current transaction, okay? Makes a lot of sense. Basically, this is a function that is used to undo any uncommitted changes made to a database transaction. If I right click and I run, you'll see that at least my program doesn't crash. Doesn't crash. But you'll see that there are a few things that have gone wrong. Especially if you open up the database and you refresh, what are the things that went wrong? The things that went horribly wrong. Is that right now in the database, if I look at the account, you'll see that I have Michael 10.5 but right here I have that Michael has 24.8 and then 22. So the deposits and the withdrawals are actually working, but they are not registered in the database, which is a huge problem. It's a huge problem. So what we need to do is we need to fix the way we are setting the balance right here. We set the balance regardless of what happens. And that is not correct right before the finally, we need to add an L's because remember, the Ls only works when there are no errors or no exceptions. And then we will have the following, what's the issue here? Just one line, okay? So now we should, let's try and take back this zero and write changes in the transactions. I will also delete this one. Write the changes. Now if I write click and I run, boom, there we go. We have 10.5 for Michael. And if I refresh and go into the account, yes, they are the same. We've fixed one of the errors. But something to consider here is that we wouldn't even want to commit our database anyway. This would be a good idea for many reasons because the less we do unnecessary transactions or get unnecessary accesses to our database, the better. Because there could be leaking, there could be data damage, whatever. So we're going to do the following right here. We're not going to commit unless we have made sure that there are no exceptions so we can get rid of the Finally and I kept it purposefully because I wanted you to see the process of our understanding. If I had put the Db.com directly on else you might have been thinking like, why didn't we do it in? Finally, why don't we commit anyway? So that's why I did it right here. But as a final touch, it's a good idea to move the DB commit above the update of our balance attribute. Now why is that? This makes sure that the balance is not updated in case the commit failed for some reason. It can happen a lot. Sometimes you're trying to access the database. You might think that everything is working. In our case right now because it's a local database and we're using Sqlite, accessing the database is not a huge problem. But when you're interacting with a server and you're doing SQL commands, there might be hiccups along the way because you're working through the Internet. You know, sometimes not everything works as smoothly as intended. So making sure that you first have an error on the commit before you update the balance attribute is a good idea because you don't want to have discrepancies between the balance that the person sees, the user that's using this ATM or this account sees the underscore balance. They don't see the actual database. The database is the back end. This is the front end. So you might be asking yourself, why would we want to roll back a transaction if commit is no longer being called anyways, we were using the rollback in order to make sure that none of the committed changes work. So why should we roll back this anyway? Well, let's run the code and look at Thomas in our accounts. Boom, If you look right here, we have Thomas that has 400 if we delete him, and then we try to run this again. As you can see, nothing really much changed except for something weird happening in here. Why is it slowing down? I think there was some kind of error or some kind of slow. Okay, let me try this again. What's happening? Stop bank account. Okay. Keyword interrupted, line 29. Okay, let me just delete this, right click and run again. So you might be asking yourself, why would we want to roll back our transactions if the commit is no longer being called? Because now we've moved the commit from the finally into the else. So it will not execute unless we have everything working and there are no errors. And as I told you, the rollback function is used to undo any uncommitted changes. So what is its use currently? Well, let me show you. First of all, I want to move the creation of these three people control shift and move them down to the end. Okay? This is going to be very crucial. Holding down control shift and moving these three people to the bottom. Now I'm going to go into my database and I'm just going to delete Thomas. And I'm going to write this change. Now if I write Click and I run, you will see that we have everything working normally, right? So we have Michael 10.5 If we look at the database and we refresh, you'll see that we have Thomas and again the transactions haven't changed. What is the actual issue in here? Well, if I try to remove the roll back, so I will comment this line out. I'm going to add a pass because you cannot keep the accept without anything in it. So I'm just going to add a pass. If I now go back to my database and I delete Thomas and I write the change, and I try to run this again. If you look at the output, we can see that Michael has 10.5 which is, you know, it's acceptable because we haven't made any changes in here. Why? Because there's no correct primary key, blah, blah, blah. But we did not make a rollback and nothing changed. Right? Well, if I look at my database and I refresh, there's something horrible that, that just happened. Michael actually now has 7.7 instead of 10.5 Which is a big, big deal with me. When you look at the code, it looks like normal, right? There shouldn't be any problems in here. Well, I'm not going to tell you what it is. I'm going to issue you a challenge. To find the problem, you need to go through the code step by step and understand what happens at every line of code in order to find the problem. Yes, this is a huge challenge, but if you can figure this out, I can say with 100% certainty that you have finally understood how to work with Python and SQL. So pause the video right now and go do the challenge. Welcome back. How did you get on with that? So in order to understand what is happening in here, we need to examine our code very carefully. Now, a hint should have been very obvious here that it happens when we delete Thomas, and then Thomas is created again. Let's go and look at what happens when Thomas gets created, or any object for that matter, inside of the construction or constructor. The constructor is called, the cursor executes. Okay? We get the row, we fetch one. If the row is there, then we have the name and the balance equal to the row. And we say that the account was retrieved is the account is already there in the database. Great. Perfect. No problem. But what happens when the account is actually created from scratch? We have the name, we have the balance we insert into the account, and we commit. And the account is created. If you haven't gone through or weren't able to complete the challenge, try to think which line. The problem is obviously here because it's when the object is created, where do you, which line has the issue? Which line is creating the terrible thing that's happening? It should be pretty obvious that it's happening on the commit, on this line. What we're doing is right here we are doing the execution of these lines. We are updating the account balance and we are inserting into the transactions. Now the transactions aren't working because we have one right here. We've made sure to avoid this issue, but what's happening is the balance is actually being updated. We're doing the command, we're not committing, but we're also not rolling back. When Thomas gets created, after we've made the deposits and withdrawals, It means that every single thing that we've done right here actually gets updated in the database because it's committed right here. When you commit a change, it doesn't just happen exactly where you've said, all the commands are written down and then boom, when you commit, everything is committed with it. Again, let me re explain this even though we're not committing right here in the safe update. Because Thomas is created after all of these withdrawals and deposits. And when Thomas is created, we have a commit, which means that everything that we've done with the update and the insert and everything we've done throughout this entire database will get committed eventually because we're creating Thomas. And inside of Thomas, we're not committing Thomas especially. We're just committing all the command lines that we've tried to do on this connection right now in this session. That's very important to understand. Having the rollback is super important because in this situation, when we do have a rollback, we roll back these transactions right here. So let me try and delete everything to go so that we have everything working smoothly. I need to write the changes, write click, run, okay? Now let's go back. Right, click accounts refresh, Michael is 10.5 All right. Everything is good. If I write click and I run again, this shouldn't be an issue because we still haven't recreated thomas anyway. So if we try to delete thomas from the database, for him to be recreated again, right changes, right click run. Thomas was created again, not retrieved. Now if we go back into the database, we should see when we refresh that the value on Michael hasn't changed. Why? Because we are rolling back the latest transactions that we did. I hope that was obvious. The next video, we are going to be changing to a different project, which is going to be the Netflix browser, which will have TK Enter. Which is something that at the moment where I'm recording we haven't covered yet. But if you follow the steps, it's a very easy thing to understand, very basic stuff, the minute details are not going to manage. So don't freak out when you get that part. The more important part is to understand how we can recreate gooey. Thank you so much for watching and I will see you in the next video. Bye bye for now. 155. 21. Creating Netflix (sort of): Welcome back my favorite Python programmers to a brand new video. And in this one we're going to be starting with our Netflix browser. The Netflix browser is going to be obviously not as sophisticated as the one that you watch. But we are going to be using our movie database that we've seen before in order to create a graphical user interface where we will be able to choose a genre, choose a movie in that genre, and then select one of the actors. Obviously, these things will just be displayed onto our screen using the Gooey. I'm not going to delve too deep into the small intricacies of using K inter, which is the tool or the module that we're going to be using to create this graphical user interface. I will later on be creating separate projects. Maybe by the time you're watching this current section, I will have a full TK intercourse. But to be honest with you, it's not something that I find is worth really talking about. Because most people that create a graphical user interface use other tools than TK Inter and there are more modern ways of creating graphical user interface. But I just wanted to have the simplest thing because our main focus here is going to be the connection between a database and Python. Without any further ado, let's go ahead and get started by creating a new project right here at the top, which is going to be the Netflix browser Browser. Browser, Is that have you, right browser? Yes, I think so. I will open it in this window right now. The first thing we need to do is we need to go to the movie database that we've seen before. And we need to click and open this in the Explorer, inside of the Netflix browser. In here, I'm going to send in the database that we have. Where is the database? Right here, the movies. And actually I'm going to copy and paste it right here. Now we have VDB inside of the Netflix folders, and you should see right here that we have VDB. Just as a cool exercise, I'm going to open this database right here in the database browser so we can take a look at it, so we can drag in the movies. Boom. And there we go. So as you can see, we have all of our actors, We have our genres, and we have our movies, and we also have the views that we've created as well. So how cool is that? You can go through the database that we had, the movie database through this DB browser, but make sure that you don't delete or add anything. Be careful with that. With that out of the way, let's now continue on. The first thing we need to do is to create a new dot py file, which will be the movie browser. So we'll be the movie underscore browser. And IntellJ just crashed. Excellent. Use the power of editing to see you in a few seconds. Hey, welcome back. So it took me a while. With the power of editing. It should have been a minor inconvenience, so I'm importing SQA Lit and I'm also importing TK Inter. This is going to be the tool that we use to create our Gooey stands for graphical user interface, just in case it wasn't clear. So in here we're going to create the connection which is equal to Schulte three connect and we are connecting to the Netflix or to the movies file right here. The only issue is if we keep on using movie B, it's not going to connect correctly. It's going to have some issues Now, I'm going to use it anyway, okay? Because I like to take risks and I want to see what would happen, and in case we have to change it, The next thing we want to do is we want to start creating the window for our graphical user interface. This video will be all about creating that window, but first we need to actually see this window. And this is the final result that we should have. We will have the genres, movies and actors, and we're going to have the list of genres. The list of movies and the list of actors. And every single time we click on one of these, we're going to get the others. I know, not that impressive, but hang in with me. So first of all, this is the dissection. We are going to have 1234 rows. So these are the numbers 012.3 these are our rows. The first row will indicate the label, so the genre, movie and actors. The second row is going to be, or the row number one will indicate the actors and the movies. Row number two. Combined with row number one will indicate the genres. Now the reason I did this is not for anything in particular, but I just wanted to show you how we can create a big list box that spans two rows. Just some extra stuff in here. I know this doesn't look pretty at all, but hang in with me. And then three is just going to be this empty space in here, so it doesn't look bad. And we also have the columns, so we're going to have 012.3, Obviously, of course the three will just be for expansive purposes. And we are going to have the first column for the genre, second column for the movies, Third one for the actors. Without any further ado, let's go ahead and create this window back in here. First thing we need to do in K inter is create the main window. And we'll say that the main window is equal to K terk K and it's a function. Then we're going to say that the main window title is going to be net flicks rouser. Every main window also needs a size geometry, and it's going to be 1024 by 768. There we go. This is the creation of the main window. Just to start testing things out, we need to make the main loop. I will add a comment in here, equal sign or h, should we use dashes or equal signs, We'll use equal signs here. We'll have the main loop and 31234567, Right? Do we have seven here? Just copy so we can have symmetry. Okay, we do have seven in here. We will say that the main window mainloop. And then we'll print out that we are closing the connection. And connection, close. Add an extra line when I write, Click and I run, boom, there we go. We've created the Netflix browser. Now, obviously we still have a lot to do in here. But this is a start. Let's close this down, and let's continue closing the connection. I can close this right here, and I can close this right here. The next thing we want to do is we want to create all of these columns and rows right here under this. We're going to say that we have main window column, column configure. On the column configure, we're going to have zero with a weight of two. Then we are going to duplicate this four time. This is going to be the spacer column on the right. This is the last one, and these three are going to be the main ones. I'm going to have 012.3 with a weight of two. Now using weights and changing weights around will depend on, or will affect when we make this window smaller and bigger. How it will affect these columns, it will become more evident when we start adding things in there. Now other than the columns, we also need to create the roles, I will say main window roll configured in here. I'm going to have zero and the weight will be equal to one. And I will duplicate this three times. The windows in the middle will have a weight of five. In here we're going to have 012.3. There we go. These are our columns. Obviously, they are not going to be apparent when we run the program because these are just dissections of our main window. There's nothing more much to it right now, but we're going to see it once we start creating, first of all, the labels. Again, I will add this comment right here to distinguish between labels. Is it the labels? Yes. Okay. So, as I told you, I'm not the best at pronunciations at the English K, inter label. And we're going to put it in the main window, The text is going to be grid in order to set it somewhere. And we're going to say that we have row equal zero and the column will be equal to zero. Now when I write, click and I run, we should see at the top, Genre is excellent. As you can see, we've anchored to the main window. It should be in the main window. The text is genres on the grid. We set it to row zero, column zero. The grid allows us to set it in the correct rows and columns. I will duplicate this because we are also going to have the movies. And the actors, the role is going to stay the same because, well, obviously we are on the same road. The only difference is going to be the column, so this will be column one and column two. When I write Click and I run bone, There we go. Now I think we can start testing how this is going to change. Look at that. So as you can see, these are all because of the way that we've dissected the weights. So we make sure that we can never really crush them. From the bottom, we can crush them, but from the side we cannot. It will always have some space. Notice how when we expand it, it's not symmetrical. It's because of the extra column that we added on the side. Let's continue on, and now let's create the genres list box. The genres list box. First of all, we need to create a list box. We're going to have the list equal to K enter list box. It's going to be in the main window. Now we need to set it properly. We're going to have Genre list grid and we're going to set it in row number one, column zero. We have to set something that is the sticky and we will set it to southeast west. It means we want to expand it on the entire column that we have. Then we're going to make sure that the row span is two because remember the genres is going to span both rows. Also we set it to northeast. It's going to cover this entire diagonal in here, at diagonal, it's going to cover the, let's just call it the entire box that we have. By the way, if you're asking why are these two not symmetrical, It's because of the shape that I've created for this browser in order to take a screenshot out of it. Row span is two, because it spans two rows. And finally, we have to add a bit of padding on the right hand side, 30.0 You can always hover over these things to see what they mean or you can always go search for them and the documentation. Now it's giving me an error expected type union. I think it will solve itself. I don't think there's any huge issues. Finally, we need to configure this. We're going to add a small border and relief. All of these are just small minute details about the style that we're going to have. So when we write, click and we run, boom. Look at that. As you can see it spans two columns. It would have been symmetrical, but what I did when I took a screenshot is I made it like this. Okay. Now, as you can see things are starting to get funky in here when we start adding things. K inter is not the most friendly beginner, friendly thing. Honestly, I don't like it too much, but I just wanted to stick with the basics for this lesson. The next thing we want to do is we want to create the movies list box. The movies list box is going to be just slightly different in here. I'm going to have the movies list box. We're going to have the movie list variable because the genres are always going to stay the same. We're not going to be changing genres, but the movies are going to change. If you select the action genre, for example, you're going to have different movies. If you select the documentary, you're going to get different movies. There is going to be a list variable which is going to be equal to the K inside of the main window. And then we're going to have the movie variable set. And we're going to set it for now to just choose the genre in here. I'm going to open this up and I'm going to say choose a genre, obviously. First of all, the movie list is going to be empty. And then once we choose a genre, we are going to have all of the movie list. Then we're going to do the same thing that we've done with the genre list. But of course this is going to be the movie list. Copy and paste it in these two places. The list box is the main window. The row is going to stay one, the column is going to be two, and the row span is going to be one. We're going just remove it, then we have movie configure border two sunken. I think all of this is good except for, I think this one is going to cause us a bit of a problem. But when we run, we should see that it's in the act. Interesting. Why do we have it in the actors? Let's see, you said column two. It should be column one, right click run, and there we go. But as you can see, we don't have choose a genre. Why is that? Because as I suspected, we need this to be a couple. We need to stop this from running and now run it again. We still don't get anything in the movies. I apologize. This is why it's better not to copy and paste code because we forgot on the list box to add the list variable equals list variable. Now it will show. There we go. Let's try not to have a top because that was not the issue. Okay, There we go. So it does not work because now we have three elements instead of just one. So we do need to have a topple in here. There we go. Because it's one element. If we don't provide it with the topple, it just thinks that each one of these is a separate element and prints it out. There we go. Now we have the movie's list box. Now obviously the last thing to do is to create the act actors list box. It's going to be a challenge for you to create the actors use the same code with the necessary adjustments to create the actors list box, close the database connection at the end, or we've already done that. Pass the video right now and go do the challenge. Welcome back. How did you get on with that? I'm just going to select all of this and paste it in here. And I'm going to have actors list box in here. Change this to to then copy paste. Paste in here. And then this will be the actors list. Yeah. All right, copy paste, paste. And of course the column is going to be two north, south, east and west, so we are putting them to all sides. Padding 30, border two relief sunken list variables, Close what we choose. We choose a movie, right click, run, and there we go. Ladies and gentlemen, some of you might be going crazy right now. But trust me, this is not something that's too complicated. If you do want to go deep into TK inter there are a lot of documentations but as you can see, like these are very elementary things to be honest with you. Like I don't see the real need to explain every single small minute detail here. Our focus is not on creating a graphical user interface, it's focused on creating a solid database and this was the start. Thank you so much for watching. I will see you in the next video where we will be adding the scroll bar next to our list, which is a complicated topic. As you'll see, I will see you in a few. Bye bye for now. 156. 22. Adding Scrollbars to Lists: Welcome back my favorite Python developers. And this video we'll start adding scroll bars in order to scroll through our data. First things first, in the genre list box, we're going to add the genre scroll. In here I'm going to have genre scroll. And it will be equal to K scroll, scroll bar. There we go. Then we're going to have the main window. We need to set the orientation to be vertical, K, enter vertical. Then we are going to have the command be equal to general list y view. Just the y view without the function parentheses. Then we're going to have the genre scroll grid. And we're going to set it, of course, on row number one. It will be column column zero, sticky, north, south, east, this we're not expanding to the west of the side. And then the row span will be two, because remember the genre span two rows. The genre list is going to have this y scroll command which will allow us to actually scroll through the data that's in the genre list and then scroll set. That is how we would create this. Now if I right click and boom, look at that. I have a scroll bar right here on the right hand side of the genres. Now before we continue on, I just wanted to show you how we can add some information to the movie list variable. For example, we've already seen it for any variable for that matter, because it will be part of your challenge. For example in here I can add 12345, okay? So when I write click and I run, this is what I get, 1,234.5 inside of the movie list. And this is going to be crucial when we want to start testing out our scroll bars. With that out of the way, now it's time for a bit of a challenge for you to add scroll bars to the other two list boxes, create a couple of 100 elements added to the genres to check if the scroll bar is actually working. Pause the video right now and go do the challenge. Welcome back. How did you get on with that? Just like we had in the genres. I will copy this and I will paste it in the movies. And this will be the movie scroll, copy, paste. And then the list in here. And then the movie scroll. And what else do we need to change? Of course, the column is going to be one, the rose pan will not be present in here. We also need to change this to the movie list. And I think that is all, if I'm not mistaken. Yes, I think we're going to copy this as well. Put it in the actors. This will be the actors scroll. Copy based actor. Actor scroll actors list. We should be good to go. If I write click and I run nice, our weight. We forgot the column. Here is two. There we go. We have our scroll bars, very nice. Now the next thing is to add a topple of 100. And this is going to be very simple. All that we need to do is we need to first of all, create in here the test list. And it will be equal to a range of 100. Oh my God, 100. And then we are going to convert this into a couple of the test list. And I think I told you in the genres. Okay, you can put it in the genres, we can put it actually in the genres. We can't put it, we need to create a variable for the genres which is a mistake that I did. We'll put it in the movies Red click run and there we go. You can see that now we have a scroll bar that we can use, even the mouse wheel on. Thanks so much for watching. I hope you enjoy it. In the next video, we will be importing our database and actually representing the movies that we have. I will see you there. 157. 23. Importing Our Database: Welcome back my fellow Python programmers to a brand new video. And in this one we're going to be importing our database and populating our list boxes with actual information from that database. The first thing we need to do is we need to go into our genres list box and well, just import data to it. So we already opened the connection with the movies Dob and as I told you in the first video, we might need to change it to ask you a light for this to work. But first of all, we'll try with the B and we'll see if it works. Because sometimes things change from time to time. And when I use different folders, different databases, it works, sometimes it doesn't, we'll just test it out. We're going to do four Genre in Connection Execute and then I'm going to select Genres, Genre name from order, order by genres. That is our first command. And then for every single one, we're going to get genre list, insert, boom. And then we are going to put it at the end. So we'll do end, end, end. There we go. Then we're going to put in the first element that we receive. Basically what we want to make sure of is that there, once we bring the genres from the database, we want to put them at the end of the list, not at the beginning. This ensures that we do this, that we put it always at the end. We are also extracting from the genre, the first element that we receive when I write, Click Iron. Boom. How cool is that? We have crime drama, comedy and documentary. And obviously the comedy and documentary are from what we've added before we should remove them. I do recommend that you remove them so we have cleaner looking Netflix browsers. But that is up to you next. Have the ability to click on one of these genres and have all of the movies appear in front of us. To do it, we need to have a way to actually select them. We're going to create a new function that is going to be the get movies. I'm going to actually create it right here at the top. I'm going to define get movies where I'm going to send in an event. And you're going to understand what I mean by event. The event is going to be the click. I'm going to have LB equal event widget. I'm going to have the index. Trust me, all of these lines are going to be explained in slides. Don't worry. Next we're going to have the LB, which is the actual reference to the list box. It's going to be the cursor selection, but for some reason I'm not getting data in here any references. Anyways, no worries. Then we'll have the genre underscore name equal to LB. Get no indications at all index because this will be Apple, that's why we've added a. Then we're going to have the genre underscore ID equal to connection execute. I will select genre ID from genre where genres name is equal to the placeholder. In here we'll have the genre name, that's why it was Apple. We will just fetch one. Then we're going to create a genre list. And it will be equal to just an empty list. And we're going to say four row in connection execute. And now we're going to connect it with the movie titles. I'm going to select movies, title from movies. Let's just enter here because it's going to be a long line where the movie genre ID is equal to what to replacement field. And then we're going to order by movies, title genre ID. In here we're going to have the genre list populated with the first element that we get from these roles which are going to be the movies. Then finally in here we're going to have the movie list variable set. And we're going to convert the genres list into a population. We're also going to set the actors list variable to choose a movie, even though we've already done it, but we want to take it always back. Choose a movie. Once we populated, come on. All right. So add a space in here. Add a space in here. This is our get movies. What is happening in here? Now I want you to open this code in front of you and then look at the following slide. So first of all, we have LB equals event widget. This gives us the list box reference, so we can use it. So this is a reference to said list box when we actually click on one of the elements. Next, we want to fetch this element. Which element have we actually clicked inside of the list list box. The or selection function used on a list gives us a topple of the elements. And we want to get the ID's out by accessing the first element. We click on one of the items inside of our list. We get access to that element, and now we have a reference to it. We have to extract from that index the name of the genre that we clicked on. We do the following LB, get index. This line retrieves the value of the selected item at the specified index using the get. And the trailing comma converts it into a topple with a single element, because remember we're going to be using it later on in our placeholder. Then we have the genre D equals connection execute. And everything inside this selects the genre ID from the genre table, filtering based on the provided genre name and the fetch one method that you see at the end is going to retrieve the first row of the result and then the value of the genre ID is assigned to the genre ID variable. Finally, we have the four loop which selects the name column from the movie stable or the title filtering based on the genre ID obtained earlier. And the results are ordered by the name column. The four loop iterates over each row and we receive the query result TLDR too long to read. Basically what's happening is we are referencing the list box, that's why I called it LB, by the way. Then we access the index. Where did we click on that list box? Then we get the information from that index. We click somewhere in the list box, we extract the information. And now we can use that information, which is the genre name, to go through our database and find the genre ID. Once we find the genre ID, we can go into the movie table and based on the genre ID, get all of the movies that we have in there. For row D connection, we are going to append our list, our genres list. Actually I'm thinking here, maybe we should change this to the movie genre list. The movie genre list, I think it's better because we are populating the movies list. This should make more sense. The movie list variable set. We convert this into a couple and then we change on the final, which is the on the actors list variable set. Choose a movie in order to populate the actors. Let's see if this works. If I write click and I run, then you can see that if I click on Crime, Interesting, I still don't get any. Well, we actually need to bind this method or call it in the genres right here at the bottom. I'm going to say that the genre list, but I will the clicking of the box select. And this is an event that happens when we do, we get movies, but we're not calling the function, this is the actual event, the list box select. When I click on Adventure, I don't get anything because I have an error, which tells me that. Not rock. There we go. So now when I write, click and I run. Hopefully this time when I click on Adventure, I get Pulp Fiction and Lord of the Rings, Return of the King. If I click on the crime, I get the Godfather drama, Comedy Action. Of course, in comedy and documentary we don't have anything. And you can see right here on the actors, we choose movie. So if I choose movie, well I don't get anything. I just get an error. And this error will always be common for some reason. I just can't figure out how to fix it. But anyway, we have a working selection. The next thing to do is to do the same for our get actors. So it will be a challenge for you, which is to create the get actors. So use the same code as in the get movies to create the method actors. Make sure to make the necessary adjustments in the code and the query. And pass the video right now and go do the challenge. Okay, welcome back. So I am going to select all of this and just control D to duplicate. I'm going to call this Get Actors. I'll be event widget course. Select the movie name, sorry, the movie name get index the movie ID. And we're going to have movie name here and we're going to have movie ID here. Select the movie ID. Movies do movie ID from the movies where movies title is equal to the movie name and we fetch one. We have the actors movie list actors list. Copy this and paste it in the, in these two places. And then we select the act first name from actors. And where the movies where the actors do movie ID order by the act first name we go. Then on this one I don't think we need to add anything on the actors variable. We will be setting it right here. We'll be actually setting the actors movie list to a list variable, to a couple of the actors movie list. Yes, this is, I think everything. The last thing to do is to actually bind it. Acts are actually movies in here. I'm going to have the list bind. We're going to list box select. Come on the get actors not calling it. Everything is set, I believe. I don't think we have anything else. Right, Click, run. We have an error because this is badly formed. Where are we talking about? Okay, Binds here. It doesn't, I'll, Right, there we go. So we select action, we select the dark night, and we get all of the actors except for this still error that I cannot just get over because it just doesn't make any sense. We are selecting everything properly, but unfortunately, as you can see, we don't get. Now, the last thing I would like to change is, for example, if I click on Drama. Okay. I have a different list or is it good actually know what I think we are all done in here. Ladies and gentlemen, thank you so much for watching. I hope you enjoyed and this is basically the end. I'm not sure if we are going to do anything extra later on. Actually, no. I do believe that we are going to be adding much more projects to this master class. Thank you so much for watching. Thank you for going through this entire course. Trust me now, with all the knowledge, if you really took the time to understand everything that we've done so far, I mean, there's nothing stopping you from becoming an amazing, amazing, amazing Python developer in whichever field that you want, whether it be data science, data analytics, or anything else for that matter. Ladies and gentlemen, thanks so much for watching. It has been an honor teaching you. And I will see you anywhere that we can see each other, any social media, anywhere else. I will always be there. Thank your instructor. Be grateful for their help and I will. Yeah, that's it. I'm not sure what to say. This is the end. We're just wrapping up. I hope we got to know each other on a deeper level. Bye bye for now.