# dense to sparse from numpy import array from scipy.sparse import csr_matrix # create dense matrix A = array([[1, 0, 0, 1, 0, 0], [0, 0, 2, 0, 0, 1], [0, 0, 0, 2, 0, 0]]) print(A) # convert to sparse matrix (CSR method) S = csr_matrix(A) print(S) # reconstruct dense matrix B = S.todense() print(B)