Eric Harley wrote: > Hi all, > > Is there a way to fill a rectangle or polygon with a color and/or > transparency gradient? This would be extremely useful for me in terms > of adding some additional information to some plots I'm making, > especially if I could define the gradient on my own by putting > functions into rgb something like rgb( r=f(x,y), g=f(x,y), b=f(x,y), > alpha=f(x,y) ). Not so important whether the coordinates are in terms > of the plot axes or normalized to the polygon itself somehow. Ideally > it would work not only for a fill color but also for shading lines. > > 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. > Hi Eric,
You can fill a rectangle with a "gradient" (slices of colors) using gradient.rect in the plotrix package. Filling an arbitrary polygon would be a lot harder to program. You may also be interested in the color.scale function that assigns colors to numerical values. Jim ______________________________________________ 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.