How to Create Truly Independent Copies of Nested Lists in Python?

Copying Nested Lists: Preserving Independence

When working with nested lists, it's often desirable to create an independent copy of the list, ensuring that modifications made to one list do not affect the other. This is not as straightforward as with one-dimensional lists, where a shallow copy using [:] is sufficient.

For two-dimensional lists, the naive approach of using [:] results in a shallow copy, where the inner lists are still referenced by both the original and the copy. As a result, modifications made to the copy are reflected in the original.

To achieve true independence, a deep copy is required. This involves creating a new object for each element in the list, including any nested lists. The copy.deepcopy() function provides a straightforward way to achieve deep copies, effectively breaking the reference link between the original and the copy.

By using copy.deepcopy() as follows, we can create an independent copy of the two-dimensional list a:

import copy
b = copy.deepcopy(a)

Now, any changes made to b will not affect a, and vice versa.

The above is the detailed content of How to Create Truly Independent Copies of Nested Lists in Python?. For more information, please follow other related articles on the PHP Chinese website!