Never mind. Solved. “cuts” argument back in levelplot(). Duh. On Nov 25, 2013, at 4:27 PM, Don McKenzie <d...@u.washington.edu> wrote:
> Bert or anyone else familiar with RColorBrewer: > > Has anyone tried to accomplish with RColorBrewer what I asked about in my > original post (below)? > > Here is an example cribbed from the levelplot() help examples > > x <- seq(pi/4, 5 * pi, length.out = 100) > y <- seq(pi/4, 5 * pi, length.out = 100) > r <- as.vector(sqrt(outer(x^2, y^2, "+"))) > grid <- expand.grid(x=x, y=y) > grid$z <- cos(r^2) * exp(-r/(pi^3)) > > # now use RColorBrewer to get a palette > > library("RColorBrewer”) > levelplot(z~x*y, grid,col.regions=brewer.pal(6,"BrBG”)) # the numeric > argument to brewer.pal is the number of colors used — I tried several > > This gives me a nice brown-to-green gradient but does not (AFAICS) give me > control over where the center of the divergence lies. Even in this symmetrical > example, I can’t get it to be at zero — it repeats on either side of zero. > > thanks to anyone who pages through all this and makes a suggestion, even if > it doesn’t work. :-) > > On Nov 22, 2013, at 10:25 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > >> Use the Rcolorbrewer package. >> >> -- Bert >> >> On Fri, Nov 22, 2013 at 8:43 PM, Don McKenzie <d...@u.washington.edu> wrote: >>> I would like to produce a levelplot with divergent colors such that >>> increasingly negative values of Z get darker in the first color and >>> increasingly >>> positive values get darker in the second color. this is common in >>> cartography. I have tried tinkering with the col.regions argument but the >>> best I can do >>> is to get the split in the middle of my range of Z, but in my particular >>> case range(Z) is (-1,12). >>> >>> I am using R 3.0.2 on OSX 10.9 >>> >>> Here is an example >>> >>> x <- y <- c(1:25) >>> grid <- expand.grid(x=x,y=y) >>> grid$z <- sort(runif(625,min=-1,max=12)) >>> levelplot(z ~ x*y,grid) # produces the default pink and blue but the >>> split is at ~5.5 >>> >>> # do something clever here >>> # e.g., my.colors <- <create a palette that splits at zero> >>> >>> levelplot(z ~ x*y,grid,col.regions=my.colors) # so there should be some >>> light pink at the bottom and the rest increasingly intense blue >>> >>> Ideas appreciated. Thanks in advance. >>> >>> >> >> Bert Gunter >> Genentech Nonclinical Biostatistics >> >> (650) 467-7374 > > Don McKenzie > Research Ecologist > Pacific Wildland Fire Science Lab > US Forest Service > > Affiliate Professor > School of Environmental and Forest Sciences > University of Washington > d...@uw.edu > > > Don McKenzie Research Ecologist Pacific Wildland Fire Science Lab US Forest Service Affiliate Professor School of Environmental and Forest Sciences University of Washington d...@uw.edu ______________________________________________ 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.