color.scale {plotrix} | R Documentation |
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.
color.scale(x,redrange,greenrange,bluerange,scale.up=FALSE)
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. |
A vector of hexadecimal color values as used by col
.
# 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))