[R] heatmap color distribution

[Jacob Michaelson]

Hi all,

I've got a set of gene expression data, and I'm plotting several  
heatmaps for subsets of the whole set.  I'd like the heatmaps to have  
the same color distribution, so that comparisons may be made  
(roughly) across heatmaps; this would require that the color  
distribution and distance functions be based on the entire dataset,  
rather than on individual subsets.  Does anyone know how to do this?

Thanks in advance,

Jake