In Python, copying a list isn't as simple as using =, which only creates a reference to the original list. If you want to make a real copy, Python provides several effective methods.

Why Not Use =

Using the assignment operator (=) doesn't copy a list. It only creates another reference to the same list.

Example:

list1 = ["apple", "banana", "cherry"]
list2 = list1
list2.append("orange")
print(list1)

Output:

['apple', 'banana', 'cherry', 'orange']

Both list1 and list2 point to the same object.

1. Copy Using list.copy()

Creates a shallow copy of the list.

Example:

original = ["apple", "banana", "cherry"]
copied = original.copy()
copied.append("orange")
print("Original:", original)
print("Copied:", copied)

Output:

Original: ['apple', 'banana', 'cherry']
Copied: ['apple', 'banana', 'cherry', 'orange']

Best for shallow (non-nested) lists.

2. Copy Using list() Constructor

Another way to make a shallow copy.

Example:

original = ["apple", "banana", "cherry"]
copied = list(original)
print(copied)

Output:

['apple', 'banana', 'cherry']

3. Copy Using Slicing ([:])

A clean and common method to copy lists.

Example:

original = [1, 2, 3, 4]
copied = original[:]
print(copied)

Output:

[1, 2, 3, 4]

4. Copy Using copy Module (deepcopy() for Nested Lists)

Use copy.deepcopy() to copy nested lists (deep copy).

Example:

import copy
original = [[1, 2], [3, 4]]
deep_copied = copy.deepcopy(original)
deep_copied[0][0] = 99
print("Original:", original)
print("Deep Copy:", deep_copied)

Output:

Original: [[1, 2], [3, 4]]
Deep Copy: [[99, 2], [3, 4]]

Use this when copying lists with nested lists or complex objects.

Summary Table