WEBVTT 1 00:00:00.000 --> 00:00:01.270 Hi Guys, and welcome back. 2 00:00:01.270 --> 00:00:02.580 In this video, we're going to learn 3 00:00:02.580 --> 00:00:05.040 how to add a legend to our charts, 4 00:00:05.040 --> 00:00:06.790 so that it's a bit easier to see 5 00:00:06.790 --> 00:00:09.760 what colours mean what in the plot. 6 00:00:09.760 --> 00:00:10.893 So, let's get started. 7 00:00:11.780 --> 00:00:14.410 Here we've got our chart from the last section, 8 00:00:14.410 --> 00:00:16.550 and we're going to press Play in here, 9 00:00:16.550 --> 00:00:18.760 and you can see that we get our chart. 10 00:00:18.760 --> 00:00:22.330 And we've got the blue and the orange colours, 11 00:00:22.330 --> 00:00:24.180 but it's not entirely clear what they mean. 12 00:00:24.180 --> 00:00:26.720 So, that's where the legend is gonna come into play. 13 00:00:26.720 --> 00:00:31.330 The first thing to do is to go ahead into our bar call here, 14 00:00:31.330 --> 00:00:33.060 and we're going to add a label. 15 00:00:33.060 --> 00:00:36.000 The label can be added to basically any plot. 16 00:00:36.000 --> 00:00:39.520 And it is used if you want to, when creating a legend. 17 00:00:39.520 --> 00:00:41.670 So, we're going to do men, 18 00:00:41.670 --> 00:00:45.610 and then in here, we're going to do label equal women. 19 00:00:45.610 --> 00:00:49.850 Now, just doing this won't do everything that we want. 20 00:00:49.850 --> 00:00:51.770 We've now given the plots a label, 21 00:00:51.770 --> 00:00:54.750 but we've not asked pyplot to create a legend. 22 00:00:54.750 --> 00:00:56.270 So, that's the next bit. 23 00:00:56.270 --> 00:00:58.460 We have to go ahead and down here, 24 00:00:58.460 --> 00:01:00.780 say axes dot legend, 25 00:01:00.780 --> 00:01:02.620 and that is going to generate a legend 26 00:01:02.620 --> 00:01:05.660 for the axes then have these plots. 27 00:01:05.660 --> 00:01:07.080 So, we can run it again. 28 00:01:07.080 --> 00:01:10.170 And now you can see we get men and women there. 29 00:01:10.170 --> 00:01:12.160 Pyplot is actually pretty smart with a legend. 30 00:01:12.160 --> 00:01:15.520 It's not always appearing in the top right hand corner. 31 00:01:15.520 --> 00:01:19.070 If you've got some short bars here and some long bars here, 32 00:01:19.070 --> 00:01:22.360 pyplot is often smart enough to move this over to the left. 33 00:01:22.360 --> 00:01:23.900 And, but it's not always perfect, 34 00:01:23.900 --> 00:01:25.773 so just bear that in mind as well. 35 00:01:26.720 --> 00:01:28.570 So, this was the first and simplest way 36 00:01:28.570 --> 00:01:30.330 of defining a legend. 37 00:01:30.330 --> 00:01:32.260 However, sometimes it can be useful 38 00:01:32.260 --> 00:01:36.420 to manually assign a legend item to individual plots. 39 00:01:36.420 --> 00:01:37.520 So, let's do that. 40 00:01:37.520 --> 00:01:40.020 We're gonna get rid of these labels, 41 00:01:40.020 --> 00:01:42.930 and instead, we're going to assign these plots 42 00:01:42.930 --> 00:01:44.100 to specific variables. 43 00:01:44.100 --> 00:01:47.250 So, we'll say men plot equal that, 44 00:01:47.250 --> 00:01:50.760 and women plot equal that. 45 00:01:50.760 --> 00:01:52.410 Now, when we've got this, 46 00:01:52.410 --> 00:01:56.190 we can then use them when we're creating our legends. 47 00:01:56.190 --> 00:01:58.100 So, what we do is in here, 48 00:01:58.100 --> 00:02:00.990 in the legend call, we pass in a tuple of plots. 49 00:02:00.990 --> 00:02:03.120 So, that's men plot and women plot. 50 00:02:03.120 --> 00:02:05.790 And then another tuple of labels. 51 00:02:05.790 --> 00:02:08.053 So, that's men and women. 52 00:02:09.290 --> 00:02:11.760 As you can see, that produces exactly the same output. 53 00:02:11.760 --> 00:02:14.570 I'm not entirely sure which one I prefer just yet. 54 00:02:14.570 --> 00:02:17.220 In this one, the legend is defined in one place, 55 00:02:17.220 --> 00:02:19.490 which is nice in terms of readability. 56 00:02:19.490 --> 00:02:22.100 But when you assign a label to each plot, 57 00:02:22.100 --> 00:02:26.170 then you allow pyplot to generate the legend for you 58 00:02:26.170 --> 00:02:28.690 from all the plots in the axes. 59 00:02:28.690 --> 00:02:30.970 So, it's up to you whether you want to create a legend 60 00:02:30.970 --> 00:02:32.830 for everything that has a label, 61 00:02:32.830 --> 00:02:34.770 or just for the things in here. 62 00:02:34.770 --> 00:02:36.720 And, but I wanted to show you both ways 63 00:02:36.720 --> 00:02:40.040 because they both can come in handy in different situations. 64 00:02:40.040 --> 00:02:41.860 Alright. Thank you guys for joining me in this video. 65 00:02:41.860 --> 00:02:44.560 Thanks for watching, and I'll see you in the next one.