Copying lists in python

Question

I have assigned a list to an older list. However, the new list changes too when I modify the older one. Why is this happening?

Answer 1

Assigning one list to another one simply means that both the lists will now refer to the same data. This is why any modifications to one of the lists gets reflected in the other one too. If you don't want this to happen, use copy.copy()

import copy
new_list = copy.copy(old_list)