Just make sure that when you do this, you're not initializing it with mutable objects, e.g. lists. x = [[0]] * 2 print x[0], x[1] # prints [0] [0]

Just make sure that when you do this, you're not initializing it with mutable objects, e.g. lists. x = [[0]] * 2 print x[0], x[1] # prints [0] [0] x[0].append(1) print x[0], x[1] # prints [0, 1] [0, 1] That's because the objects inside the repeated list are simply references to the same object internally.