Maps

Like for other plots, there are different approaches in R to make maps. You can use “base plot” in many cases. Alternatively use levelplot, either via the spplot function (implemented in sp and raster) or via the rasterVis package.

Here are some brief examples about making maps. You can also look elsewhere on the Internet, like here, or this for spplot and rasterVis.

Vector data

Base plots

library(terra)
p <- vect(system.file("exdata/lux.shp", package="terra"))
plot(p)

image0

n <- size(p)
plot(p, col=rainbow(n))

image1

One colour per region (NAME_1)

u <- unique(p$NAME_1)
u
## [1] "Diekirch"     "Grevenmacher" "Luxembourg"
m <- match(p$NAME_1, u)
plot(p, col=rainbow(n)[m])

image2

#text(p, 'NAME_2', cex=.75, halo=TRUE)

spplot

library(raster)
## Loading required package: sp
spplot(p, "AREA")

image3

Raster

Example data

library(terra)
b <- rast(system.file("exdata/logo.tif", package="terra"))
r <- rast(p, res=0.01 )
values(r) <- 1:ncell(r)
r <- mask(r, p)

Several generic functions have been implemented for SpatRaster objects to create maps and other plot types. Use ‘plot’ to create a map of a SpatRaster. You can zoom in using ‘zoom’ and clicking on the map twice (to indicate where to zoom to). With click it is possible to interactively query a SpatRaster by clicking once or several times on a map plot.

After plotting a SpatRaster you can add vector type spatial data (points, lines, polygons). You can do this with functions points, lines, polygons if you are using the basic R data structures or plot(object, add=TRUE) if you are using Spatial* objects as defined in the sp package. When plot is used with a multi-layer object, all layers are plotted (up to 16), unless the layers desired are indicated with an additional argument.

plot(r)
plot(p, add=TRUE)

image4

image does not provide a legend and that can be advantageous in some cases.

image(r)
plot(p, add=TRUE)

image5

Multi-layer Raster objects can be plotted as individual layers

plot(b)

image6

They can also be combined into a single image, by assigning individual layers to one of the three color channels (red, green and blue):

plotRGB(b, r=1, g=2, b=3)

image7

You can also use a number of other plotting functions with raster objects, including hist, persp, contour}, and density. See the help files for more info.