[R] color palette

[array chip]

Thanks for the suggestion. I still could not figure
out how to use the function to do my job. What's
important in my job is that I have to map white color
to value 0, and then form a bue gradient for negative
values, and red gradient for positive values. The data
matrix I have is not symmetric aound 0, say 0 is at
the 18 percentile, and values range from -10 to 30.
How exactly I could do my job? Bear with me, I am new
to color, I don't quite understand how the image
function map the number is the data matrix to the
colors defined in the col argument.

Thanks


--- Thomas Lumley <tlumley at u.washington.edu> wrote:

> On Wed, 3 Aug 2005, array chip wrote:
> 
> > Hi, I have a matrix with both positive and
> negative
> > numbers, I would like to use image() to draw a
> > heatmap. How can I can design a palette (or is
> there a
> > function already available) that treat negative
> > numbers in a blue gradient and positive numbers in
> a
> > red gradient and treat 0 as white?
> >
> 
> ?colorRampPalette
> 
>  	-thomas
>