WEBVTT 1 00:00:00.090 --> 00:00:01.440 Hi Guys, and welcome back. 2 00:00:01.440 --> 00:00:02.880 In this video, we're going to learn 3 00:00:02.880 --> 00:00:04.960 how to produce an image as output 4 00:00:04.960 --> 00:00:07.470 instead of showing up the window 5 00:00:07.470 --> 00:00:10.280 that allows us to interact with the plot dynamically. 6 00:00:10.280 --> 00:00:11.960 So, let's get started. 7 00:00:11.960 --> 00:00:14.010 Of course, creating an image is going to allow us 8 00:00:14.010 --> 00:00:17.250 to save things that the user wants to keep for later. 9 00:00:17.250 --> 00:00:18.210 So, it's great, 10 00:00:18.210 --> 00:00:19.820 but there's a few things that we have to know 11 00:00:19.820 --> 00:00:21.120 about saving images, 12 00:00:21.120 --> 00:00:24.840 and a few configuration options that are available to us. 13 00:00:24.840 --> 00:00:26.740 And o, let's get started by going down here, 14 00:00:26.740 --> 00:00:28.580 and instead of plt dot show, 15 00:00:28.580 --> 00:00:33.130 we're gonna do figure dot save fig graph dot png. 16 00:00:33.130 --> 00:00:35.510 Notice that I'm no longer using plt 17 00:00:35.510 --> 00:00:38.320 because the plt dot show method 18 00:00:38.320 --> 00:00:40.190 is used for creating the window. 19 00:00:40.190 --> 00:00:43.230 It essentially handles the event loop 20 00:00:43.230 --> 00:00:45.670 that is necessary in a graphical application 21 00:00:45.670 --> 00:00:47.470 so that you can drag your mouse 22 00:00:47.470 --> 00:00:49.300 and interact with buttons, and so on. 23 00:00:49.300 --> 00:00:51.900 But when we're not creating one of those windows, 24 00:00:51.900 --> 00:00:53.800 we can use the figure directly. 25 00:00:53.800 --> 00:00:56.380 So, here we're gonna save this figure specifically 26 00:00:56.380 --> 00:00:57.500 as a file. 27 00:00:57.500 --> 00:00:59.980 And matplotlib is smart enough to know that 28 00:00:59.980 --> 00:01:01.840 because you've put dot png in there, 29 00:01:01.840 --> 00:01:03.410 you wanna create a PNG file, 30 00:01:03.410 --> 00:01:05.430 and it will take care of everything for you. 31 00:01:05.430 --> 00:01:07.550 So, let's go ahead and run this. 32 00:01:07.550 --> 00:01:09.400 And you can see that nothing seems to happen, 33 00:01:09.400 --> 00:01:12.100 but of course, we've got our file now in here. 34 00:01:12.100 --> 00:01:15.310 We can open it, and this is the output produced. 35 00:01:15.310 --> 00:01:18.210 So, you've got the white background, you've got your graph, 36 00:01:18.210 --> 00:01:19.980 the subplot adjustment 37 00:01:19.980 --> 00:01:23.150 that we defined at the bottom equals zero point 35. 38 00:01:23.150 --> 00:01:24.330 You've got your legend, you know, 39 00:01:24.330 --> 00:01:25.580 everything looks good in here. 40 00:01:25.580 --> 00:01:28.170 Let's talk about some things that you can adjust. 41 00:01:28.170 --> 00:01:29.210 The first thing is, of course, 42 00:01:29.210 --> 00:01:32.330 if you go ahead and remove this subplot adjustments, 43 00:01:32.330 --> 00:01:34.547 I'm gonna set it to the default of 0.1, 44 00:01:34.547 --> 00:01:36.550 and you run this again, you create a new image, 45 00:01:36.550 --> 00:01:38.020 it overwrites the old one. 46 00:01:38.020 --> 00:01:40.830 And what you've got here is, the labels are cut off. 47 00:01:40.830 --> 00:01:41.900 So, this is not great. 48 00:01:41.900 --> 00:01:45.130 But you can see that the figure size 49 00:01:45.130 --> 00:01:47.050 and the subplot adjustment 50 00:01:47.050 --> 00:01:50.120 is used whenever you are saving the figure. 51 00:01:50.120 --> 00:01:53.580 But we can do something in addition to this, 52 00:01:53.580 --> 00:01:57.080 which allows us to recalculate the bounding box 53 00:01:57.080 --> 00:01:59.880 of the figure before exporting the file. 54 00:01:59.880 --> 00:02:04.790 So, we're going to do bbox_inches equal tight. 55 00:02:04.790 --> 00:02:07.410 I hate this, because bbox_inches, 56 00:02:07.410 --> 00:02:10.550 should surely be a number, not a string. 57 00:02:10.550 --> 00:02:14.260 And, but when you pass in a string that equals tight, 58 00:02:14.260 --> 00:02:16.580 this is going to recalculate the bounding box 59 00:02:16.580 --> 00:02:17.960 and make sure that there's enough room 60 00:02:17.960 --> 00:02:21.230 for everything in the figure to be saved to the file. 61 00:02:21.230 --> 00:02:24.640 That is what the tight bounding box method uses. 62 00:02:24.640 --> 00:02:26.560 So, now we're going to run this again. 63 00:02:26.560 --> 00:02:27.990 And you'll see that when we do that, 64 00:02:27.990 --> 00:02:31.030 our graph now is as close as possible to the edges. 65 00:02:31.030 --> 00:02:32.560 There's a very small padding there, 66 00:02:32.560 --> 00:02:34.220 that wasn't there before. 67 00:02:34.220 --> 00:02:35.860 In fact, I'm gonna get rid of this, 68 00:02:35.860 --> 00:02:37.320 and save graph two in there, 69 00:02:37.320 --> 00:02:39.450 just to show you the difference between the two. 70 00:02:39.450 --> 00:02:40.283 There we go. 71 00:02:40.283 --> 00:02:41.116 I'll bring it back. 72 00:02:41.116 --> 00:02:43.479 This is graph one with the tight bounding box. 73 00:02:43.479 --> 00:02:46.400 This is graph two without a tight bounding box, 74 00:02:46.400 --> 00:02:50.400 and the incorrect subplot adjustment. 75 00:02:50.400 --> 00:02:51.410 So, you can see that in here, 76 00:02:51.410 --> 00:02:53.960 the subplot adjustment didn't matter as much, 77 00:02:53.960 --> 00:02:57.650 and because we still have enough room for our contents. 78 00:02:57.650 --> 00:02:59.840 However, let me bring back app dot py, 79 00:02:59.840 --> 00:03:03.540 and I'm gonna reset the subplot adjustment to 0.35. 80 00:03:03.540 --> 00:03:05.320 I'm gonna create graph three. 81 00:03:05.320 --> 00:03:07.660 I promise this is going to be the last number to craft 82 00:03:07.660 --> 00:03:09.570 that we're gonna create before it gets too confusing. 83 00:03:09.570 --> 00:03:11.987 What I'm gonna show you right now with tight set, 84 00:03:11.987 --> 00:03:14.470 and a subplot is just 0.1. 85 00:03:14.470 --> 00:03:16.090 So, that's what we had earlier. 86 00:03:16.090 --> 00:03:17.138 It looks like this. 87 00:03:17.138 --> 00:03:21.190 Now, if we have just this subplot, it looks like that. 88 00:03:21.190 --> 00:03:23.420 So, you can see that we've got the exact same amount of room 89 00:03:23.420 --> 00:03:27.120 at the bottom in terms of the size of the labels. 90 00:03:27.120 --> 00:03:30.940 But clearly, the graph was bigger than before. 91 00:03:30.940 --> 00:03:35.490 That's because when we used subplot adjustment of 0.1, 92 00:03:35.490 --> 00:03:38.530 that means that the figure was six by six 93 00:03:38.530 --> 00:03:41.480 or 600 pixels by 600 pixels, 94 00:03:41.480 --> 00:03:44.970 and 10% of it was reserved for the bottom. 95 00:03:44.970 --> 00:03:49.690 So really, the graph size was 540 in terms of height, 96 00:03:49.690 --> 00:03:51.740 then when we exported the image 97 00:03:51.740 --> 00:03:54.150 and we set bbox to tight, 98 00:03:54.150 --> 00:03:55.940 essentially that added space. 99 00:03:55.940 --> 00:03:58.730 It added enough space to display the entire content, 100 00:03:58.730 --> 00:04:02.730 whereas in graph three we did that before exporting. 101 00:04:02.730 --> 00:04:04.300 We limited the height of the graph, 102 00:04:04.300 --> 00:04:09.066 we added 35% of the height into the bottom labels. 103 00:04:09.066 --> 00:04:13.210 And then when we set to the tight method of exporting, 104 00:04:13.210 --> 00:04:15.030 it didn't have to add as much information 105 00:04:15.030 --> 00:04:17.900 because it was already almost fully visible. 106 00:04:17.900 --> 00:04:19.640 So, I hope that makes a little bit of sense. 107 00:04:19.640 --> 00:04:21.810 That's something that you have to take into account. 108 00:04:21.810 --> 00:04:23.716 If you are going to produce images, 109 00:04:23.716 --> 00:04:26.960 you normally don't have to adjust your subplots that much 110 00:04:26.960 --> 00:04:30.010 because you can use the tight bounding box setting 111 00:04:30.010 --> 00:04:32.100 to give you enough room. 112 00:04:32.100 --> 00:04:35.226 Alright, when you use bbox_inches equal tight, 113 00:04:35.226 --> 00:04:37.840 you can also add some extra padding, 114 00:04:37.840 --> 00:04:39.280 because right now you can see that the graph 115 00:04:39.280 --> 00:04:41.720 is very close to the borders, maybe you don't like that. 116 00:04:41.720 --> 00:04:43.886 So, what you can do is you can say, 117 00:04:43.886 --> 00:04:46.930 pad_inches, let's say two. 118 00:04:46.930 --> 00:04:48.490 And now, when we produce this, 119 00:04:48.490 --> 00:04:50.650 I'm going to go back to graph dot png, 120 00:04:50.650 --> 00:04:54.680 by the way, then you will get your graph with a bit of room. 121 00:04:54.680 --> 00:04:56.370 A lot of room, in this case, around the size. 122 00:04:56.370 --> 00:04:57.970 You're gonna adjust this to whatever you want. 123 00:04:57.970 --> 00:05:00.810 The default is 0.1 but you can give it a bit more room 124 00:05:00.810 --> 00:05:02.500 if you, for example, wanted to print this out, 125 00:05:02.500 --> 00:05:03.820 or you wanted to write some notes near it 126 00:05:03.820 --> 00:05:06.100 or something like that, you can do it. 127 00:05:06.100 --> 00:05:07.528 And so, that's something you can use 128 00:05:07.528 --> 00:05:10.370 if bbox_inches is tight. 129 00:05:10.370 --> 00:05:11.520 If it's not tight, 130 00:05:11.520 --> 00:05:13.820 then you're using the bounding box of the figure, 131 00:05:13.820 --> 00:05:15.590 and this will not take effect. 132 00:05:15.590 --> 00:05:17.700 So, that's something to take into account. 133 00:05:17.700 --> 00:05:18.830 I'm going to remove it for now 134 00:05:18.830 --> 00:05:20.590 because we don't really need it here. 135 00:05:20.590 --> 00:05:23.210 And I'm going to set the support adjustment to 0.35, 136 00:05:23.210 --> 00:05:24.830 because I think that's sort of something 137 00:05:24.830 --> 00:05:28.010 that we need if we ever want to show the figure ourselves. 138 00:05:28.010 --> 00:05:29.050 And, but let's take a look 139 00:05:29.050 --> 00:05:31.550 at a couple other configuration options that we can use 140 00:05:31.550 --> 00:05:32.720 when saving a figure, 141 00:05:32.720 --> 00:05:34.735 although we can use them also in other places as well. 142 00:05:34.735 --> 00:05:38.420 And that is the face colour and the edge colour. 143 00:05:38.420 --> 00:05:41.270 You can set the face colour to any colour you want. 144 00:05:41.270 --> 00:05:44.100 For example, face colour equal, 145 00:05:44.100 --> 00:05:46.910 let's say 5c44fd, for example. 146 00:05:46.910 --> 00:05:48.160 And now when we run this, 147 00:05:49.470 --> 00:05:51.752 we get a beautiful blue in the background there, 148 00:05:51.752 --> 00:05:54.880 that totally makes the text super readable. 149 00:05:54.880 --> 00:05:56.350 And yeah, you can use that 150 00:05:56.350 --> 00:05:58.950 if you want to set a background colour for your graph. 151 00:05:58.950 --> 00:06:01.400 Notice that the axes have their own face colour, 152 00:06:01.400 --> 00:06:03.650 but you can set yourself separately. 153 00:06:03.650 --> 00:06:07.340 This is the face colour of the background image. 154 00:06:07.340 --> 00:06:08.539 So, that sets that. 155 00:06:08.539 --> 00:06:11.320 You can also use edge colour 156 00:06:11.320 --> 00:06:13.530 if you want to set the colour of the border, 157 00:06:13.530 --> 00:06:15.520 I'm gonna run this and open graph.png, 158 00:06:15.520 --> 00:06:18.050 and you'll see that, you can't see that blue anywhere. 159 00:06:18.050 --> 00:06:22.380 And that's because by default, figures don't have an edge. 160 00:06:22.380 --> 00:06:24.910 So, here we're setting the edge colour, but there is no edge. 161 00:06:24.910 --> 00:06:26.470 So, there's nothing to be seen. 162 00:06:26.470 --> 00:06:29.410 We have to manually change that when we create the figure. 163 00:06:29.410 --> 00:06:32.740 We can see line width, equal five, for example. 164 00:06:32.740 --> 00:06:35.010 And now when we run this and recreate our image, 165 00:06:35.010 --> 00:06:37.423 we can open it and you can see the border there. 166 00:06:38.500 --> 00:06:40.090 Alright, so I just wanted to teach you a little bit 167 00:06:40.090 --> 00:06:41.600 about these export options. 168 00:06:41.600 --> 00:06:45.030 I think that bbox_inches equal tight is really cool. 169 00:06:45.030 --> 00:06:46.750 It means that you don't really have to worry 170 00:06:46.750 --> 00:06:49.050 about the subplot adjustment whether your labels 171 00:06:49.050 --> 00:06:50.610 are exactly gonna fit, you know, 172 00:06:50.610 --> 00:06:53.180 whether your poll title is going to be super long or not. 173 00:06:53.180 --> 00:06:55.500 After all, when you're dealing with dynamic data, 174 00:06:55.500 --> 00:06:57.160 you may not necessarily know exactly 175 00:06:57.160 --> 00:06:59.870 how much space you need in the subplots, 176 00:06:59.870 --> 00:07:03.650 This is particularly useful to give defaults to the user 177 00:07:03.650 --> 00:07:05.410 when you're doing plt dot show. 178 00:07:05.410 --> 00:07:08.200 Because they can then change that if they want. 179 00:07:08.200 --> 00:07:09.841 So, just as an example there, 180 00:07:09.841 --> 00:07:13.730 I'll bring back plt dot show, and run this. 181 00:07:13.730 --> 00:07:16.060 And remember that here we've got point three five 182 00:07:16.060 --> 00:07:18.280 in the adjustment, but you can change that 183 00:07:18.280 --> 00:07:20.220 if it turns out it's too much or too little, 184 00:07:20.220 --> 00:07:23.160 you can just go ahead and add more room or remove room 185 00:07:23.160 --> 00:07:24.960 if you don't need it as the user. 186 00:07:24.960 --> 00:07:26.200 But when you're creating an image, 187 00:07:26.200 --> 00:07:27.840 you of course don't have that capability, 188 00:07:27.840 --> 00:07:29.748 you only have the image that is produced. 189 00:07:29.748 --> 00:07:31.670 That's why I like this. 190 00:07:31.670 --> 00:07:33.850 It allows you to give the user everything 191 00:07:33.850 --> 00:07:35.750 rather than just relying on them 192 00:07:35.750 --> 00:07:37.700 to change the settings as they need. 193 00:07:37.700 --> 00:07:39.290 So, thank you guys for joining me in this video. 194 00:07:39.290 --> 00:07:42.140 Thank you for watching, and I'll see you in the next one.