On Tue, Nov 24, 2009 at 8:42 AM, Karl Ove Hufthammer <k...@huftis.org> wrote: > On Mon, 23 Nov 2009 12:21:03 -0500 David Winsemius > <dwinsem...@comcast.net> wrote: >> > I would be happy with a simple one, that just mapped negative values >> > to water colours and positive values to land colours. >> >> Searching with the strategy "color positive negative zero" in r-search >> and limiting it to r-help replies, I get this Jim Lemon reply using >> (naturally) plotrix's color.scale: >> >> http://finzi.psych.upenn.edu/R/Rhelp02/archive/90837.html >> >> The application to your needs looks pretty immediate. > > Thanks for the suggestion, but the arguments that 'color.scale' takes > (range of red, green and blue values) makes it not very useful for this > purpose. >
Have you tried my colourscheme package? Its not on CRAN but you can get it from here: http://r-forge.r-project.org/projects/colourscheme/ And can be installed thus: > install.packages("colourschemes",repos="http://r-forge.r-project.org";) [sorry about the inconsistency between 'colourscheme' and 'colourschemes'!] Vignette via r-forge's source code browser: http://r-forge.r-project.org/plugins/scmsvn/viewcvs.php/*checkout*/pkg/inst/doc/colourschemes.pdf?rev=19&root=colourscheme It defines various ways of mapping values to colours and using those colours in plots. I use topographic-style colour schemes in the examples, so this might be just what you want. The example in ?multiRamp is this: # topological colour scheme - water, land, ice: tramp = multiRamp(rbind(c(-2000,0),c(0,1000),c(1000,9000)), list(c("black","blue"),c("green","brown"),c("gray70","gray70")) ) then: > tramp(-100) [1] "#0000F2FF" - is a colour between black and blue in the ocean > tramp(500) [1] "#539515FF" - is somewhere between green and brown in the land > tramp(1500) [1] "#B3B3B3FF" - is the gray of the ice. No logarithmic colour scaling, but I do detail in the vignette how to write your own colour scheme functions that are compatible with the ones supplied. Will be glad to help more on this! Barry ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
