How To Change Colour Of Certain Elements Of A Matrix In Matplotlib Matshow?

I have an adjacency matrix of a bipartite graph (of 1's and 0's) and bi-clusters (array of arrays of rows and columns) for this matrix. How do I set different colours for elements

Solution 1:

One approach might be to make a copy of your matrix and then give distinct values to the clusters you identify.

m = a_matrix.copy()     # a copy we can change without altering the orignal
c = cluster_1           # an alias to save typing

# Naked NumPy doesn't seem to have a cartesian product, so roll our own
for i in range(c.shape[1]):
    for j in range(c.shape[1]):
        if m[c[0,i]-1,c[1,j]-1]:
            m[c[0,i]-1,c[1,j]-1] = 2

plt.matshow(m, cmap='jet', interpolation='nearest')
plt.show()

For more clusters, loop over the above, setting a distinct value for each cluster (and maybe choose or define a better colormap). I'm sure there are more efficient implementations of the cartesian product as well...