On Mon, 3 Sep 2007, Michal Gallay wrote: > Dear R Spatial Users, > > I have many DEM ASCII grid files and have produced maps(images) via > image(). The maps display e.g. slope angle, profile curvature for one area, > but calculated via different methods. > > I have searched R help, the R group, but I couldn't find out how to make R > use certain colours for certain image values, in order to be able to > compare the maps, for instance to have the same color for 0 curvature > values, no matter what is the range of values. > > If it helps, the following is applied in a 'for' loop for 20 files: > > raster.values <- read.asciigrid(fname=Files[i], as.image = FALSE, > plot.image = FALSE, colname = Files[i]) > > min.val <- min([EMAIL PROTECTED], na.rm=TRUE) > max.val <- max([EMAIL PROTECTED], na.rm=TRUE) > > image(raster.values, zlim=c(min.val,max.val), col=bpy.colors(255, > cutoff.tails = 0.1), axes=TRUE)
Set breaks= explicity, it will be passed through to image.default(); perhaps do not set zlim=, and note that there should be one more break than the number of colours. Roger > > I appreciate and thank you for help. > > Michal > > -- 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
