Python – removing element from dicts copy affects the original dict

I am copying a dict and removing element from it. But this is affecting the original dict:

ugraph = {0: {1}, 1: {0, 2}, 2: {1, 3}, 3: {2}}
print(ugraph)
graph = ugraph.copy()
graph[0].remove(1)
print(ugraph)

gives the output:

{0: {1}, 1: {0, 2}, 2: {1, 3}, 3: {2}}
{0: set(), 1: {0, 2}, 2: {1, 3}, 3: {2}}

>Solution :

Hello you need to use deepcopy in that case.

from copy import deepcopy
...
graph = deepcopy(ugraph)

copy doesn’t work here because you have a dict of mutable object(in your case dictionaries).