If you assign one array a to another array b, you are not copying it; array b is just another way to call array a. In fact, by changing the element of a, you change the value of b too, and vise versa. If you assign one Python list a to another list b, you are not copying it; list b is just another way to view list a. So, by changing the element of a, you change the value of b too, and vise versa.