Although not specifically related to r-sig-geo, I'll comment a bit - I wouldn't delete part of the cells, but rather define the transparency bit in the color. You can do that, e.g. by
> rgb(1,0,0,0.5) [1] "#FF000080" you'll get half transparent red. Note that you need a device that supports this; I'm not sure about windows screen device; X11 doesn't but Cairo does; pdf does if you specify version=1.4 or so (read ?pdf). -- Edzer Ingo Holz wrote: > Hi, > > I have two objects of "class image" (a list of x, y, z coordinates, where z > is a > matrix and x and y are row names / col names). > > I would like to overlay one of this images on top of the other. As a semi- > transparent overlay. Is this possible using function image()? > > I suppose I could set some of the z-values as NA (every second?). Could > this be a way to get a semi-transparent overlay? > > I know I could do this with a GIS or something similar... > > Thank you for your help, > Ingo > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo