plotrix (version 1.2-2)

color.scale: color.scale

Description

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, only the first two are used. If any values for a color range are less than 0 or greater than 255, that range is rescaled into 0->255. The function is useful for highlighting a numeric dimension or adding an extra "dimension" to a plot.

Usage

color.scale(x,redrange,greenrange,bluerange,scale.up=FALSE)

Arguments

x
a numeric vector
redrange,greenrange,bluerange
scale.up
Whether to scale color values less than or equal to 1 into a 0->255 range. If colors are specified in a 0->1 range, set this to TRUE or all colors will be essentially black.

Value

  • A vector of hexadecimal color values as used by col.

authors

Jim Lemon

See Also

rgb.to.hex,rescale

Examples

Run this code
# go from green to red with a constant blue value
 x<-rnorm(20)
 y<-rnorm(20)
 # use y for the color scale
 plot(x,y,col=color.scale(y,c(0,1),c(1,0),0.3,scale.up=TRUE))

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