Generate a smoothly varying set of colors
colorpanel generate a set of colors that varies
smoothly. redgreen, greenred, bluered, and
redblue generate red-black-green, green-black-red,
red-white-blue, and blue-white-red colorbars, respectively.
colors
colorpanel(n, low, mid, high) redgreen(n) greenred(n) bluered(n) redblue(n)
n |
Desired number of color elements in the panel. |
low, mid, high |
Colors to use for the Lowest, middle,
and highest values. |
The values for low, mid, high can be given as
color names ('red'), plot color index (2=red), and HTML-style RGB,
("\#FF0000"=red).
If mid is supplied, then the returned color panel will consist
of n - floor(n/2) HTML-style RGB elements which vary smoothly
between low and mid, then between mid and
high. Note that if n is even, the color mid will
occur twice at the center of the sequence.
If mid is omitted, the color panel will vary
smoothly beween low and high.
Vector of HTML-style RGB colors.
Gregory R. Warnes greg@warnes.net
showpanel <- function(col)
{
image(z=matrix(1:100, ncol=1), col=col, xaxt="n", yaxt="n" )
}
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))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.