WEBVTT 0 00:00.440 --> 00:08.390 In previous lessons, I've already mentioned how important it is in Python to be aware of your indentation, 1 00:08.390 --> 00:15.920 so we know that when we create a function like this, that every line that comes after this definition 2 00:15.920 --> 00:20.810 that is indented is going to be inside this function. 3 00:20.810 --> 00:26.930 So by indented I mean it's shifted to the right by four spaces, like this. 4 00:26.930 --> 00:32.120 So if you imagine each dot as a space then this is a single block of code. 5 00:33.200 --> 00:39.350 And if we want to continue adding to this block of code inside my function, then we would continue 6 00:39.350 --> 00:41.900 adding lines of code which are indented. 7 00:42.140 --> 00:48.860 So you have to almost visualize for yourself this invisible line around these blocks of code which are 8 00:48.860 --> 00:49.700 indented. 9 00:50.390 --> 00:57.980 Now, if my code was written like this, on the other hand, then the block of code is in fact only 10 00:57.980 --> 01:05.720 this part and this print statement will not get triggered when this function gets triggered, because 11 01:05.720 --> 01:10.340 it's independent from this function, because it's not indented. 12 01:11.030 --> 01:17.420 Now, a simple way I like to think about this kind of indentation is kind of like the file structure 13 01:17.420 --> 01:22.610 you see when you go into Finder on the Mac, or when you go into Explorer on Windows. 14 01:23.090 --> 01:29.930 If we have a function, it's kind of like a folder and anything that goes inside the function. 15 01:29.930 --> 01:36.320 For example, if I throw this file inside the function, then you notice that it gets indented right? 16 01:36.320 --> 01:43.910 And this way it shows to you very, very clearly that these two files print-hello and print-world are 17 01:43.910 --> 01:46.430 living inside this folder, 18 01:46.430 --> 01:51.110 My Function. And this is the equivalent of this code. 19 01:51.110 --> 01:57.350 We have this folder say, my_function and it contains these two lines of code. 20 01:57.890 --> 02:05.780 Now on the other hand, if I take this print-world and I put it outside of the function folder, then 21 02:05.780 --> 02:12.740 you can see that this is completely independent from that folder, and it's now indented at the same 22 02:12.740 --> 02:14.420 level as the function. 23 02:14.540 --> 02:19.730 So this is the equivalent of this code where we've got this 24 02:19.730 --> 02:20.360 print("Hello") 25 02:20.360 --> 02:28.550 being inside the my_function and this print("World") being outside and at the same indentation level as 26 02:28.550 --> 02:30.350 this function definition. 27 02:31.460 --> 02:36.570 Now the indentation gets a little bit more complicated when we have other blocks of code. 28 02:36.600 --> 02:43.770 So for example, the if, elif, else statements, they have blocks of code which need to be indented 29 02:43.770 --> 02:49.470 to be inside the block, for loops need to be indented to be inside the loop. 30 02:49.530 --> 02:55.440 And it's very important that you get used to looking at blocks of code like this. 31 02:55.560 --> 03:03.830 So for example, if we were to expand our simple my_function and add a whole bunch of code into it, 32 03:03.830 --> 03:10.490 then we would have to indent all of those lines of code by four spaces, represented by the four dots 33 03:10.490 --> 03:10.940 here. 34 03:11.180 --> 03:20.210 Now, if we wanted to have another block of code inside this if statement, then this line has to be 35 03:20.210 --> 03:23.600 indented a further four spaces. 36 03:24.080 --> 03:27.230 So this is the function block. 37 03:27.740 --> 03:31.100 This is the if block. 38 03:31.280 --> 03:34.190 This is the elif block. 39 03:34.460 --> 03:39.860 And you have to be able to see all of this while just looking at the indentation. 40 03:40.790 --> 03:46.490 If we wanted to represent this, then it's almost like creating a new folder. 41 03:46.520 --> 03:56.930 Let's call it the if sky == clear, and this if block goes inside my function, so it's indented. 42 03:57.290 --> 04:06.140 Now if I wanted to have a print statement let's call it print blue inside this if statement. 43 04:06.140 --> 04:13.610 So this is what should be executed if this function gets called and if the sky is equal to clear, well 44 04:13.610 --> 04:21.570 then this line is indented twice and that is the equivalent of four spaces in our code. 45 04:21.840 --> 04:22.950 Like this. 46 04:23.790 --> 04:28.620 Now every time I've talked about indentation, I've been talking about spaces. 47 04:28.620 --> 04:32.790 And actually there's two ways of creating indentation. 48 04:32.790 --> 04:35.130 You don't have to just use spaces, 49 04:35.130 --> 04:37.260 you can also use tabs. 50 04:37.260 --> 04:42.830 And that's created using the Tab key on your keyboard, which can look a little bit like this. 51 04:43.520 --> 04:50.210 Now there's a lot of debate around spaces and tabs where some people prefer using spaces to indent, 52 04:50.240 --> 04:52.760 other people prefer tabs to indent, 53 04:52.760 --> 04:56.960 and there's a lot of people arguing in the coding community. 54 04:56.960 --> 05:01.910 And I think this excerpt from one of my favorite shows really demonstrates this. 55 05:11.710 --> 05:12.250 [Silicon Valley TV show excerpt captions] Richard: Huh. Winnie: Richard, 56 05:12.250 --> 05:13.000 what's wrong? 57 05:13.150 --> 05:14.020 Richard: Nothing. 58 05:14.290 --> 05:14.860 Nothing. 59 05:14.860 --> 05:15.370 Literally. 60 05:15.370 --> 05:16.090 It's all good. 61 05:20.590 --> 05:21.400 Come on. Huh. [laughs] 62 05:22.000 --> 05:22.660 Winnie: Oh my God. 63 05:23.050 --> 05:24.040 Richard: I' m sorry. Winnie: Your roommates were right. 64 05:24.040 --> 05:25.150 You really hate spaces. 65 05:25.180 --> 05:27.400 Richard: No no no no, I don't...it's not hate. 66 05:27.430 --> 05:28.450 Hate is a strong word. 67 05:28.570 --> 05:35.320 Truth be told, I do have a slight preference for tabs, but that's only because I'm anal and because 68 05:35.320 --> 05:37.810 I prefer precision. 69 05:40.240 --> 05:45.820 Winnie: Well, not to pick a fight here, but if you really care about precision, wouldn't you use spaces? 70 05:46.300 --> 05:47.440 But whatever. 71 05:47.470 --> 05:50.230 Once it goes through the compiler, it's the same thing, right? 72 05:51.040 --> 05:52.120 Richard: Yeah, yeah. 73 05:52.150 --> 05:53.500 Technically, yes. 74 05:58.900 --> 06:03.310 I guess I just...I just don't understand why you...anyone would use spaces over tabs. 75 06:03.310 --> 06:06.220 Like, if it's all the same, why not just use tabs? 76 06:06.370 --> 06:08.920 Winnie: Because it could look different on other people's computers. 77 06:08.920 --> 06:11.110 Richard: Tabs create smaller file sizes. 78 06:11.110 --> 06:11.410 All right. 79 06:11.410 --> 06:12.670 I run a compression company. 80 06:12.670 --> 06:15.460 Trust me, I've devoted my life to minimalizing file sizes. 81 06:15.460 --> 06:16.810 It's what I do. 82 06:16.810 --> 06:21.040 I mean, I do not get why anyone would use spaces over tabs. 83 06:21.040 --> 06:23.410 I mean, why not just use Vim over Emacs? 84 06:23.800 --> 06:25.330 Winnie: I do use Vim over Emacs. 85 06:25.330 --> 06:26.530 Richard: Oh, God help us! 86 06:26.710 --> 06:29.350 Okay, uh, you know what? 87 06:29.350 --> 06:31.270 I just I don't think this is going to work. 88 06:31.270 --> 06:32.200 I'm so sorry. 89 06:32.200 --> 06:33.100 I mean, like what? 90 06:33.250 --> 06:35.740 We're going to bring kids into this world with that over their heads. 91 06:35.740 --> 06:37.270 That's not really fair to them, don't you think? 92 06:37.270 --> 06:39.070 Winnie: Kids, we haven't even slept together. 93 06:39.070 --> 06:39.880 Richard: And guess what? 94 06:39.880 --> 06:44.530 It's never going to happen now, because there is no way I'm going to be with someone who uses spaces 95 06:44.530 --> 06:45.460 over tabs. [End of the excerpt] 96 06:46.060 --> 06:50.560 So should you be using spaces or should you be using tabs? 97 06:50.560 --> 06:57.400 The age old question, and the extent to which people obsess over this question really shows. 98 06:57.400 --> 07:04.240 In this 2017 StackOverflow developer survey where they asked the developers, do you use spaces or do 99 07:04.240 --> 07:05.170 you use tabs? 100 07:05.170 --> 07:11.350 And then they compared it against their annual salary and somehow have managed to show that the people 101 07:11.350 --> 07:15.670 who use spaces seem to earn a lot more than the people who use tabs. 102 07:16.540 --> 07:22.960 Now, the official guide from the Python community is in fact to use spaces. 103 07:22.960 --> 07:29.350 So if you click on the section tabs or spaces, they tell you in no uncertain words that spaces are 104 07:29.350 --> 07:31.840 the preferred indentation method. 105 07:31.840 --> 07:40.480 And in fact, in Python 3, you can't mix a code file that uses tabs and spaces for indentation 106 07:40.480 --> 07:41.830 in the same file. 107 07:41.830 --> 07:49.120 And it also tells you that in order to indent a line of code, it should be indented using four spaces. 108 07:49.120 --> 07:52.000 So four hits of the space bar. 109 07:53.020 --> 07:58.180 Now, for a lot of people, that may seem quite inefficient because I have to hit my spacebar, 110 07:59.920 --> 08:03.460 four times in order to achieve a single indent. 111 08:03.460 --> 08:09.430 And you've seen how much we indent throughout our code, so it seems very, very inefficient. 112 08:09.970 --> 08:19.510 But luckily in most code editors, they actually have a setting that allows you to indent using spaces, 113 08:19.510 --> 08:28.210 changing the indent size to four, and when you hit the tab key, it will automatically insert four 114 08:28.210 --> 08:32.950 spaces, which you can tell when you're trying to highlight this space. 115 08:32.950 --> 08:36.250 You can see the cursor is jumping four times. 116 08:36.760 --> 08:44.410 This means that you get to hit tab once, and that your code is in line with the guidance, because 117 08:44.410 --> 08:49.030 behind the scenes, your code editor is inserting four spaces. 118 08:50.170 --> 08:54.520 So I hope that clears up a little bit on tabs versus spaces. 119 08:54.520 --> 09:00.310 And I highly recommend you to head over to the Course Resources and click on the link to go to the Style 120 09:00.310 --> 09:04.840 Guide for Python code, and take a look through the parts about indentation. 121 09:04.840 --> 09:10.720 Now in the next lesson, I've got a quick quiz for you to test your knowledge on indentation. 122 09:10.720 --> 09:14.350 So for all of that and more, I'll see you in the next lesson.