-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 have a look at http://colorbrewer.org/ and install the package RColorBrewer
David On Jan 7, 2006, at 20:34, bogdan romocea wrote: > Dear useRs, > > I got stuck trying to generate a palette of topographic colors that > would satisfy these two requirements: > - the pallete must be 'anchored' at 0 (just like on a map), with > light blue/lawn green corresponding to data values close to 0 (dark > blue to light blue for negative values, green-yellow-brown for > positive values) > - the brown must get darker for higher positive values. > > topo.colors() fails both requirements and AFAICS lacks any options to > control its behavior. > #---unsatisfactory topo.colors() behavior > topoclr <- function(tgt) > { > clr <- topo.colors(length(tgt)) > clr <- clr[round(rank(tgt),0)] > plot(tgt,pch=15,col=clr) > } > par(mfrow=c(2,1)) ; topoclr(-50:50) ; topoclr(-20:80) > > An acceptable solution would be something like this > grayclr <- function(tgt) > { > tgt <- sort(tgt) ; neg <- which(tgt < 0) > clrneg <- gray(0:length(tgt[neg])/length(tgt[neg])) > clrpos <- gray(length(tgt[-neg]):0/length(tgt[-neg])) > clr <- c(clrneg,clrpos) > plot(tgt,pch=15,col=clr) > } > par(mfrow=c(2,1)) ; grayclr(-50:50) ; grayclr(-20:80) > if only I could make gray() use blue/brown instead of black (I tried a > couple of things but got stuck again). > > Any suggestions? > > Thank you, > b. > > ______________________________________________ > 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 > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (Darwin) iD8DBQFDwjXx7EoGVUIQyhERAq/0AKCPKQjlqtVl+RxVlOVlGXf2WxnvSwCfdZcD mEpL3eSW8KI+eYFSSQZJvzM= =/5Ix -----END PGP SIGNATURE----- ______________________________________________ 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