> I haven't been using R very long, so it's possible that I'm just > missing something, but I haven't found anything like this in the help > files. I've tried to poke around in graphics, grid, and ggplot, > without any luck so far. I really like some of the functionality in > ggplot, and it does some nice things with continuous gradients for the > color of scatter plot points, for example, but it each individual > point (or grob) is always one solid color as far as I can tell.
ggplot supports alpha blending provided your graphics device does too (Quartz on the mac, or pdf version 1.3 or later). Have a look at the alpha function for easily making transparent colours, as well as scgradient for specifying the colour scale. Oh, I see you want a gradient fill on a polygon - that's a lot harder, and I can only suggest dividing your polygon up into smaller rectangles and filling those individually. That appears to be what gradient.rect does. Hadley ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.