tmap (version 1.6-1)

map_coloring: Map coloring

Description

Color the polygons of a map such that adjacent polygons have different colors

Usage

map_coloring(x, algorithm = "greedy", ncols = NA, minimize = FALSE, palette = NULL, contrast = 1)

Arguments

x

Either a SpatialPolygons(DataFrame) or an adjacency list.

algorithm

currently, only "greedy" is implemented.

ncols

number of colors. By default it is 8 when palette is undefined. Else, it is set to the length of palette

minimize

logical that determines whether algorithm will search for a minimal number of colors. If FALSE, the ncols colors will be picked by a random procedure.

palette

color palette.

contrast

vector of two numbers that determine the range that is used for sequential and diverging palettes (applicable when auto.palette.mapping=TRUE). Both numbers should be between 0 and 1. The first number determines where the palette begins, and the second number where it ends. For sequential palettes, 0 means the brightest color, and 1 the darkest color. For diverging palettes, 0 means the middle color, and 1 both extremes. If only one number is provided, this number is interpreted as the endpoint (with 0 taken as the start).

Value

If palette is defined, a vector of colors is returned, otherwise a vector of color indices.

Examples

data(World, metro)

World$color <- map_coloring(World, palette="Pastel2")
qtm(World, fill = "color")

# map_coloring used indirectly: qtm(World, fill = "MAP_COLORS")

data(NLD_prov, NLD_muni)
tm_shape(NLD_prov) + 
	tm_fill("name", legend.show = FALSE) + 
tm_shape(NLD_muni) + 
	tm_polygons("MAP_COLORS", palette="Greys", alpha = .25) + 
tm_shape(NLD_prov) + 
	tm_borders(lwd=2) +
	tm_text("name", shadow=TRUE) +
tm_format_NLD(title="Dutch provinces and\nmunicipalities", bg.color="white")