[Rd] Transparency convenience function
Byron Ellis
byron.ellis at gmail.com
Tue Feb 6 22:32:29 CET 2007
Hi all,
For making plots with transparency I've found the following function
quite useful when specifying colors that I thought might be of
interest (I suspect it's easier to implement under R-devel. IIRC rgb()
now takes matrix arguments):
alpha <- function(colors,alpha=1.0) {
if(alpha < 0 || alpha > 1)
stop("alpha must be in [0,1]")
apply(col2rgb(colors)/255,2,function(x) rgb(x[1],x[2],x[3],alpha))
}
--
Byron Ellis (byron.ellis at gmail.com)
"Oook" -- The Librarian
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