WEBVTT 00:00:00.000 --> 00:00:01.920 align:middle line:90% [SQUEAKING] 00:00:01.920 --> 00:00:04.320 align:middle line:90% [RUSTLING] 00:00:04.320 --> 00:00:05.760 align:middle line:90% [CLICKING] 00:00:05.760 --> 00:00:09.472 align:middle line:90% 00:00:09.472 --> 00:00:10.680 align:middle line:90% HELENA VALLICROSA: All right. 00:00:10.680 --> 00:00:12.550 align:middle line:84% So as I mentioned in other videos, 00:00:12.550 --> 00:00:14.280 align:middle line:84% in order to work with maps, we need 00:00:14.280 --> 00:00:16.980 align:middle line:84% to make sure that they are both in the same projection 00:00:16.980 --> 00:00:19.070 align:middle line:90% to avoid mismatches of the data. 00:00:19.070 --> 00:00:23.550 align:middle line:84% And to do so, I'm going to teach you 00:00:23.550 --> 00:00:27.390 align:middle line:84% how to check on the projection, how can we extract information 00:00:27.390 --> 00:00:28.200 align:middle line:90% about them. 00:00:28.200 --> 00:00:32.460 align:middle line:84% So I'm going to upload a raster map and a vectorial map. 00:00:32.460 --> 00:00:35.130 align:middle line:84% The first one is January temperature 00:00:35.130 --> 00:00:37.180 align:middle line:90% based on WorldClim maps. 00:00:37.180 --> 00:00:39.420 align:middle line:84% And the second one is going to be this vectorial map 00:00:39.420 --> 00:00:41.370 align:middle line:84% that we already used also, that is 00:00:41.370 --> 00:00:44.550 align:middle line:84% the shape of the surface of the Earth. 00:00:44.550 --> 00:00:46.860 align:middle line:84% One way to check information about projection 00:00:46.860 --> 00:00:49.650 align:middle line:90% is to use the crs. 00:00:49.650 --> 00:00:55.020 align:middle line:84% Clicking on here, we see displayed a lot of information 00:00:55.020 --> 00:00:56.580 align:middle line:90% related to this map. 00:00:56.580 --> 00:01:01.200 align:middle line:84% But sometimes we only need this chunk here. 00:01:01.200 --> 00:01:04.680 align:middle line:84% This is related to the piece of code 00:01:04.680 --> 00:01:07.280 align:middle line:84% that R needs to understand what's the projection we 00:01:07.280 --> 00:01:09.500 align:middle line:90% are working on. 00:01:09.500 --> 00:01:11.660 align:middle line:84% So if we want to go directly on checking these, 00:01:11.660 --> 00:01:13.660 align:middle line:84% we can just type projection and the map 00:01:13.660 --> 00:01:14.970 align:middle line:90% that we want to know about. 00:01:14.970 --> 00:01:17.740 align:middle line:90% 00:01:17.740 --> 00:01:21.980 align:middle line:84% And here, we have only the chunk of code related to that. 00:01:21.980 --> 00:01:25.450 align:middle line:84% We can do the same with the vectorial map. 00:01:25.450 --> 00:01:28.390 align:middle line:84% And we see that in this case, the two maps 00:01:28.390 --> 00:01:29.620 align:middle line:90% are in the same projection. 00:01:29.620 --> 00:01:32.320 align:middle line:84% So we can work with them with no problem. 00:01:32.320 --> 00:01:35.890 align:middle line:90% Also, as an extra layer of-- 00:01:35.890 --> 00:01:37.810 align:middle line:84% just to double check they match, I'm 00:01:37.810 --> 00:01:39.580 align:middle line:84% going to plot them one on top of the other 00:01:39.580 --> 00:01:42.100 align:middle line:90% to see that there's actually-- 00:01:42.100 --> 00:01:43.870 align:middle line:90% that they actually fit. 00:01:43.870 --> 00:01:46.030 align:middle line:84% I'm just going to plot the map right here. 00:01:46.030 --> 00:01:48.860 align:middle line:84% And to add the vectorial map on top of it, 00:01:48.860 --> 00:01:50.810 align:middle line:84% I just need to add this part in the code. 00:01:50.810 --> 00:01:55.880 align:middle line:84% So it means that it's going to add on top of the previous. 00:01:55.880 --> 00:01:57.920 align:middle line:84% And here, we have that the two maps-- 00:01:57.920 --> 00:01:58.970 align:middle line:90% they match. 00:01:58.970 --> 00:02:02.250 align:middle line:84% So we can work with them with absolute no problem. 00:02:02.250 --> 00:02:04.460 align:middle line:84% But in case they wouldn't be in the same projection 00:02:04.460 --> 00:02:07.070 align:middle line:84% and we would need to change one to the other, 00:02:07.070 --> 00:02:12.590 align:middle line:84% there's this function right here that it's 00:02:12.590 --> 00:02:20.300 align:middle line:84% included in the packages that we've 00:02:20.300 --> 00:02:24.020 align:middle line:84% been using, that it transforms the projection 00:02:24.020 --> 00:02:25.460 align:middle line:90% of vectorial maps. 00:02:25.460 --> 00:02:29.840 align:middle line:84% So if I'm going to change from the resolution 00:02:29.840 --> 00:02:33.680 align:middle line:84% we were using-- the projection we were using into the Mercator 00:02:33.680 --> 00:02:37.460 align:middle line:84% projection, and if I plot this right now, 00:02:37.460 --> 00:02:40.100 align:middle line:84% you're going to see that the shape of the map 00:02:40.100 --> 00:02:42.380 align:middle line:90% is totally different. 00:02:42.380 --> 00:02:45.570 align:middle line:84% And if we want to change the projection in a raster, 00:02:45.570 --> 00:02:48.830 align:middle line:84% we would have to use another function, 00:02:48.830 --> 00:02:52.560 align:middle line:84% because this one is not going to be useful for raster maps. 00:02:52.560 --> 00:02:56.010 align:middle line:84% Now I'm uploading information about soils 00:02:56.010 --> 00:02:58.080 align:middle line:90% that I took from SoilGrids. 00:02:58.080 --> 00:03:01.530 align:middle line:84% SoilGrid data, it comes in a different projection 00:03:01.530 --> 00:03:02.860 align:middle line:90% than WorldClim data. 00:03:02.860 --> 00:03:04.920 align:middle line:84% So I would need to transform one to the other 00:03:04.920 --> 00:03:07.710 align:middle line:84% in order to work with them at the same time. 00:03:07.710 --> 00:03:13.230 align:middle line:84% So just to show you how this data looks like, in this case, 00:03:13.230 --> 00:03:16.310 align:middle line:84% it's a cationic exchange capacity of soils. 00:03:16.310 --> 00:03:19.930 align:middle line:84% So you see the shape is slightly different than the other map. 00:03:19.930 --> 00:03:23.210 align:middle line:84% And just to double-check that it's a different projection, 00:03:23.210 --> 00:03:26.150 align:middle line:84% we just check on the information of the map. 00:03:26.150 --> 00:03:29.570 align:middle line:84% We have here-- on the crs, we see that the projection 00:03:29.570 --> 00:03:30.920 align:middle line:90% is different. 00:03:30.920 --> 00:03:36.080 align:middle line:84% So I am going to reproject the temperature map 00:03:36.080 --> 00:03:39.260 align:middle line:90% into the soildata extension. 00:03:39.260 --> 00:03:44.188 align:middle line:84% And to do that, I'll use this projectRaster function. 00:03:44.188 --> 00:03:45.980 align:middle line:84% This might take a little while because when 00:03:45.980 --> 00:03:49.290 align:middle line:84% we work with raster maps, we have a lot of information. 00:03:49.290 --> 00:03:52.460 align:middle line:90% So it's a very dense grid. 00:03:52.460 --> 00:03:55.010 align:middle line:84% That makes the times of processing 00:03:55.010 --> 00:03:58.375 align:middle line:84% these maps to be a little higher than possibly a vectorial map. 00:03:58.375 --> 00:04:01.140 align:middle line:90% 00:04:01.140 --> 00:04:07.060 align:middle line:84% And several minutes later, the process hopefully worked out. 00:04:07.060 --> 00:04:10.030 align:middle line:84% I'm just going to plot to see what we have. 00:04:10.030 --> 00:04:12.540 align:middle line:84% And here is the result, where we have 00:04:12.540 --> 00:04:17.070 align:middle line:84% the temperature map transformed into the soil projection. 00:04:17.070 --> 00:04:28.810 align:middle line:84% Just to double-check, we can always 00:04:28.810 --> 00:04:38.770 align:middle line:84% see how it went from the old one to this projection. 00:04:38.770 --> 00:04:43.000 align:middle line:90%