In r-tmap/tmap: Thematic Maps

knitr::opts_chunk$set(
  collapse = TRUE,
  fig.width = 8,
  comment = "#>"
)
hook_output <- knitr::knit_hooks$get("output")
knitr::knit_hooks$set(output = function(x, options) {
   lines <- options$output.lines
   if (is.null(lines)) {
     return(hook_output(x, options))  # pass to default hook
   }
   x <- unlist(strsplit(x, "\n"))
   more <- "..."
   if (length(lines)==1) {        # first n lines
     if (length(x) > lines) {
       # truncate the output, but add ....
       x <- c(head(x, lines), more)
     }
   } else {
     x <- c(more, x[lines], more)
   }
   # paste these lines together
   x <- paste(c(x, ""), collapse = "\n")
   hook_output(x, options)
 })

library(tmap)
tmap_options(scale = 0.75)

Modes

tmap facilitates two output modes: "plot", which produces static maps, and "view" which produces (using the same tmap code) interactive maps. As of version 4, tmap can also be extended with other modes, as demonstrated below.

Switching between modes

## current mode
tmap_mode()

## to view mode
tmap_mode("view")

## back to plot mode
tmap_mode("plot")

The handy function ttm() is used to toggle between the modes.

Plot mode

We start with cerating the plot and assign it to a variable called tm.

tm = tm_shape(World, crs = 8857) +
  tm_polygons(
    fill = "press",
    fill.scale = tm_scale_intervals(values = "pu_gn")) +
tm_shape(metro) +
  tm_bubbles(
    size = "pop2020",
    fill = "gold",
    size.scale = tm_scale_continuous(values.scale = 0.8, n = 8))

We are in "plot" mode. Now we can plot the map by printing tm object:

tm

View mode

The same map in view mode:

ttm()
tm

Note that there is big difference: in this "view" mode there are basemaps, and in "plot" mode none. This is caused by different default option.

Basemaps can be enabled or disabled via tm_basemap():

tm + tm_basemap(NULL)

See vignette about basemaps.

Mode specific options

Mode specific layout options can be set via tm_plot() and tm_view(). The number of options in tm_plot() is limited to just one, because it uses all general purpose options. In contrast, tm_view() contains more options, e.g. there to position the control box and what the default zoom level is:

tm +
    tm_view(control.position = c("left", "bottom"),
            set_view = 2)

For a more detailed description of options, see vignette about options.

Other modes

As of version 4, tmap can be extended with other modes. See (vignette about extensions).

library(tmap.deckgl)
tmap_mode("deck")
tm

The proof-of-concept package tmap.deckgl only features the map layer function tm_polygons() (so the bubbles are not working yet).

r-tmap/tmap documentation built on Feb. 28, 2025, 7:54 a.m.