Roger, I really thank you for you comments. You are always available to explain everything, and that's a fortune for forum users. But I still with the same problem. I did,'t understand how to leave the inner hole or the inner polygon transparent, in order to see any other layer plotter at first. Should I send a simple example?
2010/1/30 Roger Bivand <roger.biv...@nhh.no> > On Sat, 30 Jan 2010, Paulo Eduardo Cardoso wrote: > > I'd like to plot a SPDF with two objects, one of them buffering the other >> "island". How can I set the "island" transparent? >> Similarly, keeping the outer polygon only, how can the hole still >> transparent? >> > > Polygons objects are plotted largest to smallest, as are Polygon objects in > each Polygons object. Each Polygons object and all its constituent Polygon > objects are painted the colour chosen for that Polygons object. > > If you want the holes Polygon objects to overpaint their containing Polygon > objects, in the base graphics plot() method, you set the pbg= argument to > the background colour (not "transparent", this will let you see the painted > Polygon below). In the spplot method, this is handled internally by reading > the trellis.par.get()$background value, and using it if not "transparent", > or "white" if it is "transparent". > > Both approaches depend on the hole slot of the Polygon object being > correctly set. > > R graphics do not analyse objects leaving out say holes, they overpaint. > This is because the holes are not "known" in advance by the functions being > executed. > > Hope this helps, > > Roger > > >> Thanks in advance, >> >> Paulo E. Cardoso >> >> [[alternative HTML version deleted]] >> >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@stat.math.ethz.ch >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> >> > -- > Roger Bivand > Economic Geography Section, Department of Economics, Norwegian School of > Economics and Business Administration, Helleveien 30, N-5045 Bergen, > Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 > e-mail: roger.biv...@nhh.no > > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
