[R-sig-Geo] generating large, non-repeating, color palates for world maps

[Eric Carr]

200 colors seems extreme but ....   Cubehelix will generate a ramp of that
size.
http://www.mrao.cam.ac.uk/~dag/CUBEHELIX/cubetry.html
Eric

-----Original Message-----
From: r-sig-geo-bounces at r-project.org
[mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Damian Maddalena
Sent: Wednesday, August 21, 2013 4:57 PM
To: r-sig-geo at r-project.org
Subject: [R-sig-Geo] generating large, non-repeating, color palates for
world maps

I am mapping regions generated using k-means clustering of ecological
variables at a global scale. I need to generate large random color ramps
(200 and 500 colors, for example) that do not repeat and implement them in
such a way as to minimize adjacency of similar colors. I am generating my
plots using spplot.

Currently, I generate my color ramps using rainbow() with the number of
categories in the spplot call as follows:

#df is a sp object of all land surface at .5 degree resolution. I am mapping
df$clusternum, a category that ranges from 1-n, where n is the number of
clusters.

n<-200
spplot(df,zcol="clusternum",col.regions=rainbow(n,start=1/6,end=1),at=0:n)

Is there a better way to do this where I can a.) randomize the colors and
b.) minimize adjacency of similar colors?

Thank you.

-Damian

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