Hi all, I wish to plot a Boolean matrix, in which "1" is represented by black and "0" is represented by white. I first initialize a simple Boolean matrix, then issue the following command: > dd [,1] [,2] [,3] [,4] [,5] a 1 1 1 1 1 b 1 1 1 1 0 c 0 0 0 0 0 > heatmap(dd, col = c(0,1), Rowv = NA, Colv = NA) Presumably, the first row should be all black because all entries are "1", and the third row should be all white cause all entries are "0". But the heatmap shows both the first and third rows are white. When I use a large matrix with more rows, all rows but the first one (supposed to be all black) are displayed correctly. Can somebody help me out? Thanks. Dognxiao