[R] divergent colors around zero in levelplot()

[Bert Gunter]

Use the Rcolorbrewer package.

-- Bert

On Fri, Nov 22, 2013 at 8:43 PM, Don McKenzie <dmck at 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.
>
>
>
> Don McKenzie
> Research Ecologist
> Pacific Wildland Fire Sciences Lab
> US Forest Service
>
> Affiliate Professor
> School of Environmental and Forest Sciences
> University of Washington
>
> dmck at uw.edu
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

(650) 467-7374