a = np.array([[1, 0, 0], [0, 1, 0], [1, 0, 1], [0, 0, 1], [0, 1, 0], [1, 0, 1]]
    )
aa = sps.csc_matrix(a)
aa.indices[aa.indptr[0]:aa.indptr[1]]
aa.indices[aa.indptr[1]:aa.indptr[2]]
aa.indices[aa.indptr[2]:aa.indptr[3]]
Finding the indices of the rows where there are non-zero entries in a sparse csc_matrix