color palette

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

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