How to Create a True Copy of Nested Lists in Python?

Creating a Distinctive Copy of Nested Lists in Python

In Python, copying a one-dimensional list is straightforward using slice assignment (a[:]). However, this approach fails to create a distinctive copy of nested lists. Modifying one list modifies the other as well. This is because slicing creates shallow copies of the nested elements, which reference the same underlying objects.

To resolve this issue, consider using Python's copy module. The copy.deepcopy() function creates a deep copy of the original list and its nested elements. This ensures that modifications to one list do not affect the other.

Example:

import copy

a = [[1, 2], [3, 4]]
b = copy.deepcopy(a)

b[0][0] = 5
print(a)  # Output: [[1, 2], [3, 4]]
print(b)  # Output: [[5, 2], [3, 4]]

As illustrated, modifying b does not alter a, creating a true copy that can be manipulated independently.

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