Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,030 --> 00:00:06,660 Hi, welcome again and in this lecture I'll show you how to add another layer to 3 00:00:06,660 --> 00:00:12,929 this map. Currently we have two layers we have the base map which are map tiles by 5 00:00:12,929 --> 00:00:19,740 map box you can see here and the data are served by Open Street Map and you 7 00:00:19,740 --> 00:00:24,660 also have your custom layer as well which is a layer containing circle 9 00:00:24,660 --> 00:00:31,969 markers. So in GIS, geographic information systems these are referred to as layers. 11 00:00:31,969 --> 00:00:38,809 Now I'd like to add a third layer to my map and that will be a polygon layer. 13 00:00:38,809 --> 00:00:45,260 So this current layer with markers, this can be referred to as a point layer. 15 00:00:45,260 --> 00:00:51,690 You also have line layers and polygon layers so with points, points are better 17 00:00:51,690 --> 00:00:57,739 to represent locations and you have lines, lines are best for representing 19 00:00:57,739 --> 00:01:04,920 geographical features which resembles lines such as roads and rivers and then 21 00:01:04,920 --> 00:01:11,659 we have polygons. Polygons are best to represent areas so for instance in this 23 00:01:11,659 --> 00:01:17,210 lecture what I'll show you is how to add a layer, a polygon layer that represents 25 00:01:17,210 --> 00:01:25,920 world population by country, so countries are represented as areas and what we're 27 00:01:25,920 --> 00:01:31,799 going to do is each of the countries will have a specific color which will 29 00:01:31,799 --> 00:01:37,320 indicate the population of that country so points for locations lines, for lines, 31 00:01:37,320 --> 00:01:44,720 and polygons for areas. Now of course you need to have some data to create 33 00:01:44,720 --> 00:01:51,750 a polygon layer. You know just like as we did with markers we had some data in CSV 35 00:01:51,750 --> 00:01:58,950 in text format and then we used those data, we opened them with Pandas and then 37 00:01:58,950 --> 00:02:05,189 we iterated through those lines of data and we added the markers to the map. 39 00:02:05,189 --> 00:02:13,450 Now for polygons the way to add polygons via Folium is by 41 00:02:13,450 --> 00:02:21,010 using the folium.GeoJson method, so basically let me make some space here 43 00:02:21,010 --> 00:02:27,780 the way this would work is you want to add to feature group the variable here. 45 00:02:27,780 --> 00:02:37,360 You want to add a child which will be a folium.GeoJson object. So this is the 47 00:02:37,360 --> 00:02:46,030 method with brackets here that creates a GeoJSON object and for GeoJSON data we 49 00:02:46,030 --> 00:02:52,630 will use this world.JSON file. You can find this attached in this lecture 51 00:02:52,630 --> 00:02:57,340 and let me explain what this is, but careful, don't open it on Atom 53 00:02:57,340 --> 00:03:05,200 because if your computer is a bit slow your atom may crash, so try to open 55 00:03:05,200 --> 00:03:12,250 it with a lighter editor such as notepad for instance, or cat on a Linux terminal 57 00:03:12,250 --> 00:03:20,290 or Mac. Anyway this is the JSON file you can refer to it as JSON or GeoJson. 59 00:03:20,290 --> 00:03:27,370 Actually GeoJSON is a special case of JSON. Basically the format is always the 61 00:03:27,370 --> 00:03:34,090 same, it starts with curly brackets and basically it contains a string which is 63 00:03:34,090 --> 00:03:45,880 like a Python dictionary with keys and values. Keys, key and value where this 65 00:03:45,880 --> 00:03:52,299 curly bracket ends somewhere here I believe. If I'm not wrong. This one ends 67 00:03:52,299 --> 00:04:00,130 in here, yeah. Then you have the other key, geometry. So what is geometry? When the 69 00:04:00,130 --> 00:04:06,250 type of geometry is multi polygon so basically you have this kind of 71 00:04:06,250 --> 00:04:15,030 attributes that describe the data. Type multi polygon or coordinates. 73 00:04:18,480 --> 00:04:23,520 So this is now starting to describe the features, the polygons so these are the 75 00:04:23,520 --> 00:04:27,750 coordinates over the first polygon that will be displayed on the map. Let's say 77 00:04:27,750 --> 00:04:36,560 this is one specific country and that's that's, that's Antigua and Barbuda, yeah. 79 00:04:36,560 --> 00:04:43,770 A small country but anyway and these are the coordinates that will determine the 81 00:04:43,770 --> 00:04:50,010 location of the polygon in your map so basically Folium will read all this 83 00:04:50,010 --> 00:04:57,720 information and it will decide where to put the polygons and then you can also use 85 00:04:57,720 --> 00:05:04,920 other attributes of this such as population which is here, yeah. You will use 87 00:05:04,920 --> 00:05:13,050 this population value to put a color for that population and so on and so forth. 89 00:05:13,050 --> 00:05:20,280 You have all countries of the world in this JSON file, so spend a few minutes 91 00:05:20,280 --> 00:05:26,070 looking at this file to understand its structure and in the next lecture I'll 93 00:05:26,070 --> 00:05:32,570 go ahead and load the JSON file into Python and display the polygon layer. 95 00:05:32,570 --> 00:05:34,000 See you there! 5767