color.scale {plotrix}R Documentation

Turn values into colors.

Description

Transform numeric values into colors.

Usage

 color.scale(x,redrange=c(0,1),greenrange=c(0,1),bluerange=c(0,1),
  extremes=NA,na.color=NA)

Arguments

x a numeric vector, matrix or data frame
redrange,greenrange,bluerange color ranges into which to scale x
extremes The colors for the extreme values of x.
na.color The color to use for NA values of x.

Details

color.scale calculates a sequence of colors by a linear transformation of the numeric values supplied into the ranges for red, green and blue. If only one number is supplied for a color range, that color remains constant for all values of x. If more than two values are supplied, the x values will be split into equal ranges (one less than the number of colors) and the transformation carried out on each range. Values for a color range must be between 0 and 1.

If extremes is not NA, the ranges will be calculated from its values using col2rgb, even if ranges are also supplied. extremes allows the user to just pass the extreme color values in any format that col2rgb will accept.

The user may not want the color scheme to be continuous across some critical point, often zero. In this case, color scale can be called separately for the values below and above zero. See the second example for color2D.matplot.

Value

A vector or matrix of hexadecimal color values.

Note

The function is useful for highlighting a numeric dimension or adding an extra "dimension" to a plot.

Author(s)

Jim Lemon

See Also

rescale, col2rgb

Examples

 # go from green through yellow to red with no blue
 x<-rnorm(20)
 y<-rnorm(20)
 # use y for the color scale
 plot(x,y,col=color.scale(y,c(0,1,1),c(1,1,0),0),main="Color scale plot",
  pch=16,cex=2)

[Package plotrix version 2.7-2 Index]