Plotting with ggplot2
SpatRasters
tidyterra provides several geom_* for
SpatRasters. When the SpatRaster has the CRS
informed (i.e. terra::crs(a_rast) != ""), the geom uses
ggplot2::coord_sf(), and may be also reprojected for
adjusting the coordinates to other spatial layers:
library(ggplot2)
# A faceted SpatRaster
ggplot() +
geom_spatraster(data = temp) +
facet_wrap(~lyr) +
scale_fill_whitebox_c(
palette = "muted",
na.value = "white"
)
A faceted SpatRaster
# Contour lines for a specific layer
f_volcano <- system.file("extdata/volcano2.tif", package = "tidyterra")
volcano2 <- rast(f_volcano)
ggplot() +
geom_spatraster(data = volcano2) +
geom_spatraster_contour(data = volcano2, breaks = seq(80, 200, 5)) +
scale_fill_whitebox_c() +
coord_sf(expand = FALSE) +
labs(fill = "elevation")
Contour lines plot for a SpatRaster
# Contour filled
ggplot() +
geom_spatraster_contour_filled(data = volcano2) +
scale_fill_whitebox_d(palette = "atlas") +
labs(fill = "elevation")
Contour filled plot for a SpatRaster
With tidyterra you can also plot RGB
SpatRasters to add imagery to your plots:
# Read a vector
f_v <- system.file("extdata/cyl.gpkg", package = "tidyterra")
v <- vect(f_v)
# Read a tile
f_rgb <- system.file("extdata/cyl_tile.tif", package = "tidyterra")
r_rgb <- rast(f_rgb)
rgb_plot <- ggplot(v) +
geom_spatraster_rgb(data = r_rgb) +
geom_spatvector(fill = NA, size = 1)
rgb_plot
Plotting a RGB SpatRaster
tidyterra provides selected scales that are suitable for creating hypsometric and bathymetric maps:
asia <- rast(system.file("extdata/asia.tif", package = "tidyterra"))
asia
#> class : SpatRaster
#> dimensions : 164, 306, 1 (nrow, ncol, nlyr)
#> resolution : 31836.23, 31847.57 (x, y)
#> extent : 7619120, 17361007, -1304745, 3918256 (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / Pseudo-Mercator (EPSG:3857)
#> source : asia.tif
#> name : file44bc291153f2
#> min value : -9558.468
#> max value : 5801.927
ggplot() +
geom_spatraster(data = asia) +
scale_fill_hypso_tint_c(
palette = "gmt_globe",
labels = scales::label_number(),
# Further refinements
breaks = c(-10000, -5000, 0, 2000, 5000, 8000),
guide = guide_colorbar(reverse = TRUE)
) +
labs(
fill = "elevation (m)",
title = "Hypsometric map of Asia"
) +
theme(
legend.position = "bottom",
legend.title.position = "top",
legend.key.width = rel(3),
legend.ticks = element_line(colour = "black", linewidth = 0.3),
legend.direction = "horizontal"
)
Hypsometric tints
SpatVectors
tidyterra allows you to plot
SpatVectors with ggplot2 using the
geom_spatvector() functions:
lux <- system.file("ex/lux.shp", package = "terra")
v_lux <- terra::vect(lux)
ggplot(v_lux) +
geom_spatvector(aes(fill = POP), color = "white") +
geom_spatvector_text(aes(label = NAME_2), color = "grey90") +
scale_fill_binned(labels = scales::number_format()) +
coord_sf(crs = 3857)
Plotting SpatVectors
The underlying implementation is to take advantage of the conversion
terra::vect()/sf::st_as_sf() and use
ggplot2::geom_sf() as an endpoint for creating the
layer.
With tidyterra we can also aggregate
SpatVectors at our convenience:
# Dissolving
v_lux %>%
# Create categories
mutate(gr = cut(POP / 1000, 5)) %>%
group_by(gr) %>%
# Summary
summarise(
n = n(),
tot_pop = sum(POP),
mean_area = mean(AREA)
) %>%
ggplot() +
geom_spatvector(aes(fill = tot_pop), color = "black") +
geom_spatvector_label(aes(label = gr)) +
coord_sf(crs = 3857)
Union of SpatVectors
# Same but keeping internal boundaries
v_lux %>%
# Create categories
mutate(gr = cut(POP / 1000, 5)) %>%
group_by(gr) %>%
# Summary without dissolving
summarise(
n = n(),
tot_pop = sum(POP),
mean_area = mean(AREA),
.dissolve = FALSE
) %>%
ggplot() +
geom_spatvector(aes(fill = tot_pop), color = "black") +
geom_spatvector_label(aes(label = gr)) +
coord_sf(crs = 3857)
Union of SpatVector keeping the inner borders