Consensus clustering. Consensus clustering indicates that 3 clusters is the greatest number of stable clusters across clustering techniques. Consensus heat maps produced by HC and SOMs for cluster number k = 3 are shown. The consensus heat map is a visual representation of the consensus matrix, which is a matrix of sample pairs. Each matrix entry is the proportion of times the pair's samples are clustered together across resampling iterations. In the heat map, a value of 1 (corresponding to 2 samples that are always clustered together) is represented by the color red, and a value of 0 (corresponding to 2 samples that are never clustered together) is represented by the color white.