showpanel <- function(col) {
image(z=matrix(1:100, ncol=1), col=col, xaxt="n", yaxt="n")
}
oldpar <- par(mfrow=c(3,3))
# two colors only:
showpanel(colorpanel(8,low="red",high="green"))
# three colors
showpanel(colorpanel(8,"red","black","green"))
# note the duplicatation of black at the center, using an odd
# number of elements resolves this:
showpanel(colorpanel(9,"red","black","green"))
showpanel(greenred(64))
showpanel(redgreen(64))
showpanel(bluered(64))
showpanel(redblue(64))
showpanel(royalbluered(64))
showpanel(royalredblue(64))
par(oldpar)
Run the code above in your browser using DataLab