Scale bar

[danbebber]

Is it possible to add a scale bar to plots, as in terra?

f <- system.file("ex/elev.tif", package="terra")
r <- rast(f)
plot(r)
sbar(10, c(6.3, 50))

[dieghernan]

Yes, it is possible via ggspatial package:

# Your example
library(terra)
#> terra 1.7.55

f <- system.file("ex/elev.tif", package = "terra")
r <- rast(f)
plot(r)
sbar(10, c(6.3, 50))

# With tidyterra and ggspatial
library(tidyterra)
library(ggplot2)
library(ggspatial)

ggplot() +
  geom_spatraster(data = r) +
  scale_fill_terrain_c() +
  annotation_scale(style = "ticks")

Or you may give a try to tmap package, that is a complete different plotting system but provides great support for additional elements of a map such as scale bars and orientation arrows, see:

library(tmap)
#> Breaking News: tmap 3.x is retiring. Please test v4, e.g. with
#> remotes::install_github('r-tmap/tmap')

tm_shape(r) +
  tm_raster(palette = terrain.colors(10, rev = TRUE)) +
  tm_layout(legend.position = c("right", "TOP")) +
  tm_scale_bar()

^{Created on 2023-10-30 with reprex v2.0.2}