On Wed, 7 Mar 2007, Schmitt Thierry wrote: > I am struggling to overlay spatialLinesDataFrame and > SpatialGridDataFrame. The overlay method doesn't allow me to do so. >
There is no overlay method, you would need to write one, or interpolate points along your lines and overlay the resulting point object on the raster. > As mentioned by matt, I might have a look at starspan. However, I might > be interested to have some solution within the Grass/R interface Could I suggest that you try v.to.rast in GRASS, and simply use multiple rasters? You may need care with the resolution, but in spearfish: v.to.rast input=roads output=v_roads use=cat then in R: library(spgrass6) sp <- readRAST6(c("v_roads", "elevation.dem")) summary(sp) sp1 <- as(sp, "SpatialPixelsDataFrame") summary(sp1) sp2 <- sp1[!is.na(sp1$v_roads),] summary(sp2) by(sp2$elevation.dem, sp2$v_roads, summary) which just preserves the raster cells crossed by roads as defined by v.to.rast. Hope this helps, Roger > > Thierry > > _______________________________________________ > 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: [EMAIL PROTECTED] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo