stats::heatmaps shows white for higher data

Question

I have a heatmap that contains a lot of 1s and a few 0s

R) m = matrix(rep(1,25),5,5)
R) m[c(1,5,7,8,3,5)] = 0
R) m
     [,1] [,2] [,3] [,4] [,5]
[1,]    0    1    1    1    1
[2,]    1    0    1    1    1
[3,]    0    0    1    1    1
[4,]    1    1    1    1    1
[5,]    0    1    1    1    1
R) heatMap <- heatmap(m, Rowv=NA, Colv=NA, col = heat.colors(256), scale="none", margins=c(5,5), na.rm=T)

In the heat map I need scale='none' as I have sometimes matrices with only 1 or 0 (and scaling fail in that case), how can I make the heatmap to get darker colors for higher numbers ?

Answer 1

The simplest way is to just reverse the vector of heat colors:

heatmap(m, Rowv=NA, Colv=NA, col = rev(heat.colors(256)), 
        scale="none", margins=c(5,5), na.rm=T)