[R] divergent colors around zero in levelplot()

[Don McKenzie]

Thanks Bert.  I’ll check it out.

Don

On Nov 22, 2013, at 10:25 PM, Bert Gunter <gunter.berton at gene.com> wrote:

> 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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>> and provide commented, minimal, self-contained, reproducible code.
> 
> 
> 
> -- 
> 
> Bert Gunter
> Genentech Nonclinical Biostatistics
> 
> (650) 467-7374

Don McKenzie
Research Ecologist
Pacific WIldland Fire Sciences Lab
US Forest Service

Affiliate Professor
School of Environmental and Forest Sciences 
College of the Environment
University of Washington
dmck at uw.edu