If you want to copy lists, you do it by using the [:] operator. e.g.: >>> a = [1,2] >>> b = a[:] >>> a [1, 2] >>> b [1, 2] >>> b[0] = 2 >>> a [1, 2] >>> b [2, 2]
If you want to copy a list of lists, you can use a list comprehension if you do not want to use the copy module: >>> a = [[1,2],[3,4]] >>> b = [i[:] for i in a] >>> a [[1, 2], [3, 4]] >>> b [[1, 2], [3, 4]] >>> b[0][0] = "foo" >>> a [[1, 2], [3, 4]] >>> b [['foo', 2], [3, 4]] -- http://mail.python.org/mailman/listinfo/python-list
