color.scale {plotrix} | R Documentation |
Transform numeric values into colors.
color.scale(x,redrange=c(0,1),greenrange=c(0,1),bluerange=c(0,1), extremes=NA,na.color=NA)
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. |
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.
A vector or matrix of hexadecimal color values.
The function is useful for highlighting a numeric dimension or adding an extra "dimension" to a plot.
Jim Lemon
# 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)