L1 is a list of three different lists, although each list holds the same values.
L2 is a list of three references to the same list (the '*' operator doesn't do a deep copy). So when you modify any of the referenced lists, you modify all of them. Try this: >>> q = [1, 1, 1] >>> r = [q, q, q] >>> r [[1, 1, 1], [1, 1, 1], [1, 1, 1]] >>> r[0][0] = 999 >>> r [[999, 1, 1], [999, 1, 1], [999, 1, 1]] Regards, Casey -- http://mail.python.org/mailman/listinfo/python-list
