WEBVTT 0 00:00.000 --> 00:05.080 So, we're importing the turtle module in order to use it in our code. 1 00:05.080 --> 00:10.560 So I want to spend a few minutes just quickly talking about all the ways that we can import 2 00:10.560 --> 00:18.000 modules. 3 00:18.000 --> 00:21.799 So we've already seen the Basic Import and it's very simple, 4 00:21.799 --> 00:27.420 we have the keyword import and then we have the Module name that we want to import. 5 00:27.420 --> 00:33.060 So if we had just imported our turtle module with the simple import, then in order to create 6 00:33.060 --> 00:40.200 a new turtle, we would have to say the module name and then the name of the class, 7 00:40.200 --> 00:50.020 and we would create a new turtle like this. 8 00:50.020 --> 00:55.340 Now this is perfectly fine, but it would make it so much more convenient if we were using 9 00:55.340 --> 00:59.840 that Turtle class a lot to write our code like this. 10 00:59.840 --> 01:05.360 This way, we don't have to keep writing turtle.Turtle() or turtle.Whatever else it is that we want 11 01:05.360 --> 01:06.800 to import. 12 01:06.800 --> 01:08.320 And this code is again pretty simple, 13 01:08.320 --> 01:13.879 we have the keyword "from", we have the keyword "import", we have the Module name, and also the 14 01:13.879 --> 01:17.680 Thing in the module that we want to import. 15 01:17.680 --> 01:24.699 As you've seen, with this kind of syntax, we can simply write... 16 01:24.760 --> 01:28.320 And this means that if we were creating a lot of turtles, let's say, instead of just 17 01:28.320 --> 01:38.959 creating tim, we also created tom and terry, then we don't have to keep writing turtle.Turtle(), 18 01:38.959 --> 01:41.760 turtle.Turtle() every single time. 19 01:41.760 --> 01:47.160 So this from import is really helpful if you're going to use this thing that you're importing 20 01:47.160 --> 01:51.800 a lot and you don't want to keep writing the name of the module in front of it. 21 01:51.800 --> 01:54.940 Now you can actually go one step further, 22 01:54.940 --> 02:00.000 instead of saying just from turtle import whatever it is you want, you can actually 23 02:00.000 --> 02:06.180 import everything by using the asterisk. 24 02:06.180 --> 02:12.179 Now you can use everything that's in that module as if it were in the current file. 25 02:12.179 --> 02:17.979 And this has advantages as well as disadvantages, because it can make it really hard to see 26 02:17.979 --> 02:21.520 where each of these classes or methods come from. 27 02:21.520 --> 02:26.880 So for example, if I just wrote forward(), you can see I can, I can do this, 28 02:26.880 --> 02:33.080 but it's really confusing to just see this method somewhere in isolation, because it's 29 02:33.080 --> 02:35.320 like, "Well, what is moving forward? 30 02:35.320 --> 02:36.520 What's actually happening? 31 02:36.520 --> 02:39.500 Where does this come from?" 32 02:39.500 --> 02:43.759 And it's more obvious when you import a module like random. 33 02:43.759 --> 02:47.440 So from random import everything. 34 02:47.440 --> 02:52.619 And then somewhere else in our code, we might just write something like, choice(), 35 02:52.619 --> 02:58.300 and this is a method from random, where we can pick a random item from a sequence like 36 02:58.300 --> 02:59.520 a list. 37 02:59.520 --> 03:03.000 Now this code works, but it's really confusing. 38 03:03.000 --> 03:05.600 Like, "How is this choice() working? 39 03:05.600 --> 03:06.639 Where does it come from? 40 03:06.639 --> 03:10.039 Which module enables this capability?" 41 03:10.039 --> 03:13.600 Instead we just have the method whack right in our code, 42 03:13.600 --> 03:16.639 and it's very confusing as to its origins. 43 03:16.639 --> 03:21.500 So amongst the Python community, it's very unusual that you'll see good code written 44 03:21.500 --> 03:22.500 like this. 45 03:22.500 --> 03:27.320 I want you to know what it does, because you might come across it in the wild, just so 46 03:27.320 --> 03:29.800 you understand what it's actually doing, 47 03:29.800 --> 03:33.000 but I want you to try and avoid writing code like this. 48 03:33.000 --> 03:38.360 Instead, if you're using something from a module many times, so more than three times, 49 03:38.360 --> 03:41.880 then you can think about using this "from import", 50 03:41.880 --> 03:46.919 but if you're only using it once or twice, then just import the whole module and write 51 03:46.919 --> 03:49.199 out this turtle.Turtle(). 52 03:49.199 --> 03:56.000 So you can see that this module is the one that contains this class and that is imported 53 03:56.000 --> 03:59.240 and we're using it to create this object. 54 03:59.240 --> 04:09.320 It's just a lot more expressive in terms of the code. 55 04:09.320 --> 04:15.119 Now the final thing I want to show you, which is quite a useful thing, is how to Alias Modules. 56 04:15.119 --> 04:19.640 So for example, we can import our turtle as "t". 57 04:19.640 --> 04:26.619 So what this does is we import from the turtle module and we give that module an alias name, 58 04:26.619 --> 04:29.839 so a name that we define. 59 04:29.839 --> 04:35.519 And what this means is that if you were to create your new object from the module turtle, 60 04:35.519 --> 04:40.600 instead of writing out turtle every single time, you can just write "t", and it will represent 61 04:40.600 --> 04:42.119 the entire module. 62 04:42.119 --> 04:45.440 So sometimes you'll have modules which are really, really long. 63 04:45.440 --> 04:50.480 So it could have a really long name and you don't want to type it out every single time. 64 04:50.480 --> 04:55.359 So you give it an alias name and it will be exactly the same as referring to the entire 65 04:55.359 --> 04:57.399 name of the module. 66 04:57.399 --> 05:00.839 And you can create a turtle like this. 67 05:00.839 --> 05:07.239 Now, even though we've been writing import, there are some modules that you can't just import, right? 68 05:15.119 --> 05:20.959 So for example, if I wanted to import the heroes module, which is something that I can 69 05:20.959 --> 05:30.440 use to generate hero names like Decepticon or Leopardon or Askew-Tronics, then I can use 70 05:30.440 --> 05:36.119 one of the functions that's in that module, heroes, called generate. 71 05:36.119 --> 05:42.880 But if I just go into my code and I straight up try to import this module, which is called 72 05:42.880 --> 05:50.839 heroes, then you can see I get an error and the error says, there's "No module named heroes." 73 05:50.839 --> 05:55.279 Why is it that I can't do this, but I can import turtle? 74 05:55.920 --> 06:02.079 Well, the reason is because turtle is a module that's packaged with the Python standard library, 75 06:02.079 --> 06:08.200 and this is a small library of code which contains just the basics to get you started. 76 06:08.200 --> 06:13.079 Like a core set when you buy a board game or like the basic track pieces when you buy 77 06:13.079 --> 06:14.920 a set of Hot Wheels. 78 06:14.920 --> 06:20.559 So you can imagine this library of code as like a family library, easily accessible, 79 06:20.559 --> 06:22.359 but very small. 80 06:22.399 --> 06:28.040 Now, if we wanted to access the whole world of Python modules and packages, then we need 81 06:28.040 --> 06:31.559 to go to a much bigger library. 82 06:31.559 --> 06:36.880 And that is, of course, the Python packages, which are hosted on the internet and we can 83 06:36.880 --> 06:41.019 install into our project as and when we need them. 84 06:41.019 --> 06:46.519 So this way, our final project doesn't become gigantic because we've got all of the modules 85 06:46.519 --> 06:48.519 loaded into it from the internet, 86 06:48.640 --> 06:52.839 instead, we only plug and play whatever it is we need. 87 06:52.839 --> 06:57.399 So PyCharm is actually already smart enough to know that I probably want a module that 88 06:57.399 --> 06:59.239 I haven't installed. 89 06:59.239 --> 07:04.880 And you can see that as soon as I click on this error with the red underline, I get a 90 07:04.880 --> 07:07.559 red light bulb over here. 91 07:07.559 --> 07:13.079 And if I click on it, it gives me the prompt to install this package called heroes. 92 07:13.079 --> 07:20.880 And once it's done, then we can actually tap into this module and we can say heroes.gen(), 93 07:20.880 --> 07:24.920 and this is going to generate us a new hero name. 94 07:24.920 --> 07:30.679 So let's go ahead and run our code. 95 07:30.679 --> 07:37.000 And you can see we've got a name called Galvatron, which is not bad, actually. 96 07:37.000 --> 07:42.640 So it's important to remember that when you try to import something that hasn't been installed, 97 07:42.640 --> 07:47.920 like this villains package, then when you try to run the code, you'll get an error that 98 07:47.920 --> 07:50.959 says, "No module named villains". 99 07:50.959 --> 07:56.160 And this should prompt you to think, "Uh, maybe that module is not a part of the Python standard 100 07:56.160 --> 08:00.399 library like turtle, and I actually have to install it." 101 08:00.399 --> 08:05.239 Just remember that before you can import a module, sometimes if it's not bundled with 102 08:05.239 --> 08:10.160 the Python standard library, then you might have to install it. 103 08:10.160 --> 08:18.119 Now what happens when you install a package is it gets installed into the local virtual 104 08:18.119 --> 08:24.660 environment, which as we said previously, is on a per project basis. 105 08:24.660 --> 08:30.000 So this is stored in the .venv or virtual environment folder, 106 08:30.000 --> 08:37.020 and you can see it here, heroes and villains, as well as other modules in Python. 107 08:37.020 --> 08:40.739 Now, for the most part, you don't need to touch this folder at all, 108 08:40.739 --> 08:43.659 you can leave it as it is already set up for you. 109 08:43.659 --> 08:49.219 And when you create new projects in PyCharm, it usually gets created automatically for you. 110 08:49.219 --> 08:57.619 So this is an important differentiation between modules, like what we import here, and software. 111 08:57.619 --> 09:02.179 So when you install software, for example, PyCharm, you only need to install it once 112 09:02.179 --> 09:06.859 and it's available globally across your computer. 113 09:07.700 --> 09:14.539 Now with a virtual environment, and with these packages, they get installed into the project 114 09:14.539 --> 09:15.539 that you're building. 115 09:15.539 --> 09:21.380 So for example, today we're building day-18-start, and these two modules are available 116 09:21.380 --> 09:22.859 in this project, 117 09:22.859 --> 09:24.859 but if I was to start a new project, 118 09:32.859 --> 09:39.460 then you'll see that those packages are not installed by default. 119 09:39.460 --> 09:41.780 So they're not global. 120 09:41.780 --> 09:47.700 The reason why we need to work with virtual environments when using Python is actually 121 09:47.700 --> 09:49.739 a bit of a historical problem. 122 09:49.739 --> 09:54.340 So previously, there was a version of Python called Python 2, 123 09:54.340 --> 09:59.140 and then people wanted new features to Python, so they created Python 3. 124 09:59.140 --> 10:05.020 However, sadly, Python 3 is not what we call backward-compatible with Python 2. 125 10:05.020 --> 10:11.059 So it means that if you have code that's written in Python 2, and then you try to add Python 126 10:11.059 --> 10:14.020 3 to that project, it's not going to work. 127 10:14.020 --> 10:19.659 So you kind of have to make a choice, either Python 2 project, or projects written in Python 128 10:19.659 --> 10:20.659 3. 129 10:20.659 --> 10:23.419 Now, we all know that Python 3 is the future, 130 10:23.419 --> 10:28.640 but that doesn't mean that there isn't a lot of existing projects written in Python 2. 131 10:28.640 --> 10:32.780 So the transition has been really, really slow, 132 10:32.780 --> 10:39.479 and virtual environments help us in a way by defining a small sandbox for our project. 133 10:39.479 --> 10:44.760 So we can decide whether we want to use Python 2 or Python 3 for our project, 134 10:44.760 --> 10:49.679 and then because we're in a virtual environment, we can install the modules that we need, for 135 10:49.679 --> 10:54.919 example, the heroes module, which works with Python 3, but not Python 2. 136 10:54.919 --> 11:00.299 And we know that because we have our virtual environment set up for each and every project, 137 11:00.299 --> 11:05.200 and it's different for every single project, then when we install each module, we know 138 11:05.200 --> 11:06.880 that it's compatible, 139 11:06.880 --> 11:11.559 we know that that particular version works with all of the other packages that we have 140 11:11.559 --> 11:12.559 installed, 141 11:12.559 --> 11:17.239 and it's kind of like freezing that project in time, so that you know, once you compile 142 11:17.239 --> 11:22.039 everything, once your program runs, you can continue running that program as and when 143 11:22.039 --> 11:29.080 you want, even if things like Python change versions, or your modules change versions. 144 11:29.080 --> 11:37.080 So that's one of the reasons why we want to use PyCharm to handle and install our modules, 145 11:37.080 --> 11:41.400 because it means that it works with the rest of our virtual environment. 146 11:41.400 --> 11:46.239 It ensures that there are no errors that occur when we install it. 147 11:46.239 --> 11:53.080 And we maintain the version that we use, so that our final project works as expected. 148 11:53.080 --> 11:57.559 Now some of you might have seen that you can also install these packages using pip. 149 11:57.559 --> 12:02.559 So you could go into the terminal and write "pip install..." and pick one of these projects. 150 12:02.559 --> 12:08.000 But as you can imagine, with virtual environments, with the different projects having different 151 12:08.000 --> 12:12.880 virtual environments, you might install these modules into the wrong location, 152 12:12.880 --> 12:18.280 and that means your project won't be able to access them outside of the sandbox. 153 12:18.280 --> 12:23.520 So I recommend following the video and doing what I do in the videos, so that we can all 154 12:23.520 --> 12:27.559 be on the same page and we can all learn as quickly as possible.