tmap (version 4.0)

tm_raster: Map layer: raster

Description

Map layer that draws rasters. Supported visual variable is: col (the color).

Usage

tm_raster(
  col = tm_vars(),
  col.scale = tm_scale(),
  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,
  zindex = NA,
  group = NA,
  group.control = "check",
  options = opt_tm_raster(),
  ...
)
opt_tm_raster(interpolate = FALSE)

Arguments

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

Visual variable that determines the color. See details.

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

Visual variable that determines the color transparency. See details.

zindex

Map layers are drawn on top of each other. The zindex numbers (one for each map layer) determines the stacking order. By default the map layers are drawn in the order they are called.

group

Name of the group to which this layer belongs. This is only relevant in view mode, where layer groups can be switched (see group.control)

group.control

In view mode, the group control determines how layer groups can be switched on and off. Options: "radio" for radio buttons (meaning only one group can be shown), "check" for check boxes (so multiple groups can be shown), and "none" for no control (the group cannot be (de)selected).

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)

Details

The visual variable arguments (e.g. col) can be specified with either a data variable name (e.g., a spatial vector attribute or a raster layer of the object specified in tm_shape()), or with a visual value (for col, a color is expected). See vignette about visual variables.

Multiple values can be specified: in that case facets are created. These facets can be combined with other faceting data variables, specified with tm_facets(). See vignette about facets.

• The *.scale arguments determine the used scale to map the data values to visual variable values. These can be specified with one of the available tm_scale_*() functions. The default is specified by the tmap option (tm_options()) scales.var. See vignette about scales.

• The *.legend arguments determine the used legend, specified with tm_legend(). The default legend and its settings are determined by the tmap options (tm_options()) legend. . See vignette about legends.

• The *.chart arguments specify additional charts, specified with tm_chart_, e.g. tm_chart_histogram(). See vignette about charts.

• The *.free arguments determine whether scales are applied freely across facets, or shared. A logical value is required. They can also be specified with a vector of three logical values; these determine whether scales are applied freely per facet dimension. This is only useful when facets are applied (see tm_facets()). There are maximally three facet dimensions: rows, columns, and pages. This only applies for a facet grid (tm_facets_grid()). For instance, col.free = c(TRUE, FALSE, FALSE) means that for the visual variable col, each row of facets will have its own scale, and therefore its own legend. For facet wraps and stacks (tm_facets_wrap() and tm_facets_stack()) there is only one facet dimension, so the *.free argument requires only one logical value.

Examples

if (FALSE) {
# load land data
data(land, World)

tm_shape(land) +
	tm_raster("cover")

tm_shape(land) +
	tm_raster("elevation", col.scale = tm_scale_continuous(values = terrain.colors(9))) +
	tm_shape(World) +
	tm_borders()
}