Tuszynski, Jaroslaw W.
2006-Jan-09 14:43 UTC
[R] need palette of topographic colors similar to topo.colors ()
I will second Roger's suggestion, colorRampPalette is a great function for creating your own palettes. For example, Matlab's jet palette (also available in fields package under peculiar name 'tim.colors') can be defined by: jet.colors = colorRampPalette(c("#00007F", "blue", "#007FFF", "cyan", "#7FFF7F", "yellow", "#FF7F00", "red", "#7F0000")) Other predefined functions for creating and managing color palettes that I know of, are: * R provides functions for creating palettes of continuous colors: rainbow, topo.colors, heat.colors, terrain.colors.colors, gray * tim.colors in package fields contains palette similar to Matlab's jet palette (see examples for simpler implementation) * rich.colors in package gplots contains two palettes of continuous colors. * Functions brewer.pal from RColorBrewer package and colorbrewer.palette from epitools package contain tools for generating palettes * rgb and hsv creates palette from RGB or HSV 3-vectors. Maybe one of those will work for you. Jarek -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] Sent: Saturday, January 07, 2006 3:10 PM To: bogdan romocea Cc: r-help Subject: Re: [R] need palette of topographic colors similar to topo.colors() On Sat, 7 Jan 2006, 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?Use colorRampPalette() to roll your own, or something better tuned, perhaps catenating two ramps together.> > Thank you, > b. > > ______________________________________________ > R-help at 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>-- 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.Bivand at nhh.no ______________________________________________ R-help at 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