Rotwang <sg...@hotmail.co.uk> wrote: > Can anybody tell me what's going on?
Your problem is basically this: >>> a = [1] >>> b = [a] * 2 >>> b [[1], [1]] >>> a.append(2) >>> b [[1, 2], [1, 2]] The expression '[a] * 2' doesn't make two copies of list of a list of a, it makes two nested _references_ to it. When you modify the 'first' list, you're seeing that changed reflected in the second reference. The list comprehension, however, is returning a _new_ list each time. Changing its contents doesn't affect any of the other independently created lists. -- http://mail.python.org/mailman/listinfo/python-list
