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tmap extensions: tmap.mapgl

Source: vignettes/ext_mapgl.Rmd
ext_mapgl.Rmd

There are two modes included in tmap: "plot" for static mapping and "view" for interactive mapping. See introduction. The "view" mode uses the JavaScript library Leaflet as backend.

The extension package tmap.mapgl offers two new modes which are also interactive: "mapbox" and "maplibre" which use the JavaScript libraries Mapbox GL and Maplibre GL respectively. An API key is required to use "mapbox" (free for personal use), but "maplibre" is (as the name suggests) free for any use.

Note that tmap.mapgl is a bridge between the R packages mapgl and tmap. It makes the functionality of mapgl (making the JavaScript libraries available to R) also available via the tmap user interface.

For this example we’ll create a choropleth of well being per country. We assign the map to map without showing it.

map = tm_shape(World) + 
  tm_polygons("well_being",
    fill.scale = tm_scale_continuous(values = "pu_gn"))
tmap_mode("plot")
#> ℹ tmap mode set to "plot".
map
#> [tip] Consider a suitable map projection, e.g. by adding `+ tm_crs("auto")`.
#> This message is displayed once per session.

mapbox

For "mapbox" an API key is required, which is free for personal use. See instructions.

tmap mapbox mode
tmap mapbox mode

maplibre 

tmap_mode("maplibre")
#> ℹ tmap mode set to "maplibre".
map

3d polygons

tmap.mapgl also features a new layer type, tm_polygons_3d, which is only available for "mapbox" and "maplibre".

This map layer is the same as tm_polygons, but one addition: polygons can be extruded in 3d shape. The visual variable to control this is called height.

tmap_mode("maplibre")
#> ℹ tmap mode set to "maplibre".

NLD_dist$pop_dens = NLD_dist$population / NLD_dist$area

tm_shape(NLD_dist) +
  tm_polygons_3d(height = "pop_dens",
    fill = "edu_appl_sci",
    fill.scale = tm_scale_intervals(style = "kmeans", values = "-pu_gn"),
    fill.legend = tm_legend("Univeristy degree")) +
tm_maplibre(pitch = 45)
#> No legends available in mode "maplibre" for map variables
#> "height"