Copying Lists in Python

List Satellite

Copy Lists Correctly

Cloning a list sounds simple, but references make it tricky. Learn all the options and when to use them.

Compare techniquesDeep copy nested data

Techniques

Method	Example	Notes
Slice	copy = original[:]	Shallow copy
.copy()	copy = original.copy()	Shallow copy
list()	copy = list(original)	Shallow copy
copy.copy()	copy.copy(original)	Explicit shallow copy

All shallow copies duplicate the list container but keep references to the same elements.

Deep copy

import copy
deep = copy.deepcopy(nested)

Use deep copy when nested structures must be independent. Recursive objects or custom classes may need __deepcopy__ defined.

Next up in your learning path

Mutability primer

Understand why copying matters.

Companion

Nested lists

Apply deep copies to multi-dimensional data.

Practice

Copy dictionaries

Extend concepts to other containers.

Tip