tmap (version 4.0)

tm_rgb: Map layer: rgb images

Description

Map layer that an rgb image.. The used (multivariate) visual variable is col, which should be specified with 3 or 4 variables for tm_rgb() and tm_rgba() respectively. The first three correspond to the red, green, and blue channels. The optional fourth is the alpha transparency channel.

Usage

tm_rgb(
  col = tm_vars(n = 3, multivariate = TRUE),
  col.scale = tm_scale_rgb(),
  col.legend = tm_legend(),
  col.chart = tm_chart_none(),
  col.free = NA,
  col_alpha = tm_const(),
  col_alpha.scale = tm_scale(),
  col_alpha.legend = tm_legend(),
  col_alpha.chart = tm_chart_none(),
  col_alpha.free = NA,
  options = opt_tm_rgb(),
  ...
)
tm_rgba(
  col = tm_vars(n = 4, multivariate = TRUE),
  col.scale = tm_scale_rgba(),
  col.legend = tm_legend(),
  col.chart = tm_chart_none(),
  col.free = NA,
  options = opt_tm_rgb()
)
opt_tm_rgb(interpolate = FALSE, saturation = 1)

Arguments

col, col.scale, col.legend, col.chart, col.free

Visual variable that determines the color. col is a multivariate variable, with 3 (tm_rgb) or 4 (tm_rgba) numeric data variables. These can be specified via tm_vars() with multivariate = TRUE

col_alpha, col_alpha.scale, col_alpha.legend, col_alpha.chart, col_alpha.free

Visual variable that determines the color transparency. See details.

options

options passed on to the corresponding opt_<layer_function> function

...

to catch deprecated arguments from version < 4.0

interpolate

Should the raster image be interpolated? Currently only applicable in view mode (passed on to grid)

saturation

The saturation of the rgb.

Examples

if (FALSE) {
require(stars)
file = system.file("tif/L7_ETMs.tif", package = "stars")

L7 = stars::read_stars(file)

tm_shape(L7) +
	tm_rgb()

# the previous example was a shortcut of this call
tm_shape(L7) +
	tm_rgb(col = tm_vars("band", dimvalues = 1:3, multivariate = TRUE))

# alternative format: using a stars dimension instead of attributes
L7_alt = split(L7, "band")
tm_shape(L7_alt) +
	tm_rgb()

# with attribute names
tm_shape(L7_alt) +
	tm_rgb(col = tm_vars(c("X1", "X2", "X3"), multivariate = TRUE))

# with attribute indices
tm_shape(L7_alt) +
	tm_rgb(col = tm_vars(1:3, multivariate = TRUE))

if (requireNamespace("terra")) {
	L7_terra = terra::rast(file)

	tm_shape(L7_terra) +
		tm_rgb()

	# with layer names
	tm_shape(L7_terra) +
		tm_rgb(tm_vars(names(L7_terra)[1:3], multivariate = TRUE))

	# with layer indices
	tm_shape(L7_alt) +
		tm_rgb(col = tm_vars(1:3, multivariate = TRUE))

}
}