assign a value to a dict change all the values

[ichabod801]

The list is a reference too, just like the dictionary. A shallow copy of the list gives you all the items in the list. But some of those items can be references too. A shallow copy will just give you those references.

>>> x = [1, 2, 3]
>>> y = [x, 4, 5]
>>> y
[[1, 2, 3], 4, 5]
>>> z = y[:]  # shallow copy
>>> y[1] = 6
>>> y
[[1, 2, 3], 6, 5]
>>> z
[[1, 2, 3], 4, 5] # integers that are values don't have changes affect the shallow copy
>>> x[1] = 7
>>> z
[[1, 7, 3], 4, 5] # lists that are references do have changes affect the shallow copy

A deep copy would make an independent copy of everything in the list.