Hi, I found that accessing a compressed matrix is really slow. I'm computing a similarity index called LHN1, it took 34 seconds to compute when I access the 'paths' variable/matrix. But when I converted paths to paths.asarray() it only took 11 seconds. So now I'm really ending up calling toarray() all over my code. I'm not sure of why using compressed matrices in the first place or how I could overcome this! Forget about the get_degrees_dic() for now. Here's my code: def lhn1(graph): A = gts.adjacency(graph) paths = A**2 paths = paths.toarray() S = np.zeros(A.shape) degrees = get_degrees_dic(graph) for i in xrange(S.shape[0]): for j in xrange(S.shape[0]): i_degree = degrees[i] #graph.vertex(i).out_degree() j_degree = degrees[j] #graph.vertex(j).out_degree() factor = i_degree * j_degree S[i,j] = (1.0/factor) * paths[i,j] return S