I have found the sum() function to be much slower than to loop over the operands myself:
def sum_products(seq1, seq2): return sum([a * b for a, b in zip(seq1, seq2)]) def sum_products2(seq1, seq2): sum = 0 for a, b in zip(seq1, seq2): sum += a * b return sum In a program I generate about 14 million pairs of sequences of ints each of length 15 which need to be summed. The first version with sum() needs 44 seconds while the second version runs in 37 seconds. Can someone explain this difference? Steve -- https://mail.python.org/mailman/listinfo/python-list