cmap: Apply a color map to numeric data

In squash: Color-Based Plots for Multivariate Visualization

Description

Map numeric (scalars, vectors, matrices) into colors, (optionally) using a specified color map.

Usage

cmap(x, map, outlier = NULL, ...)

Arguments

x	Something numeric (vector, matrix).
map	The color map to use (as created by makecmap). If missing, a color map is created.
outlier	Color for values outside the map domain, or NULL to generate an error in case of such values (see Details).
...	Arguments passed to makecmap, if map is undefined.

Details

Values in x outside the domain of map cause either an error (if outlier=NULL) or a warning (otherwise).

Value

Something of the same size as x. May be character (RGB) or integer (palettes) depending on the color map used. Dimensions and dimnames are preserved.

See Also

makecmap. Also, as.raster and level.colors have similar functionality.

Examples

  x <- y <- 1:50
  mat1 <- outer(x, y)
  
  ## several ways of visualizing the matrix mat1:
  plot(col(mat1), row(mat1), col = cmap(mat1), pch = 16)
  
  cimage(x, y, zcol = cmap(mat1))

  colorgram(x = x, y = y, z = mat1)
  
  ## treatment of out-of-domain values
  map <- makecmap(0:100, colFn = greyscale)
  x <- y <- -10:10
  mat2 <- outer(x, y, "*")

  ## Not run: 
  ## Values outside the domain of "map" generate an error...
  plot(col(mat2), row(mat2), col = cmap(mat2, map), pch = 15, cex = 2)

  ## ... unless we specify "outlier", but this still generates a warning
  plot(col(mat2), row(mat2), col = cmap(mat2, map, outlier = 'red'), pch = 15, cex = 2)
  
## End(Not run)
  

squash documentation built on Feb. 20, 2020, 9:08 a.m.