Make Copy of Linked List in Python (2 Examples)

In this tutorial, you’ll learn how to make a copy of a linked list in Python. A linked list is a data structure where each element (node) contains a value and a reference to the next node. We’ll explore different methods to create a copy of a linked list.

The table of contents is structured as follows:

Let’s dive into it!

Initializing Sample Linked List and Importing Modules

Firstly, we will import the copy module, then we will define a linked list. To do that, we will implement a basic Node class. Afterward, we will create a couple of nodes and link them to each other.

import copy
 
class Node:
    def __init__(self, value):
        self.value = value
        self.next = None
 
# Linked List
head = Node(1)
second = Node(2)
third = Node(3)
 
head.next = second
second.next = third

Example 1: Creating Shallow Copy

The first example involves creating a shallow copy of a linked list. Here’s how it works:

# Shallow copy
new_head = head
 
# Print original linked list
current_node = head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 2
    # 3
 
# Print shallow copy
current_node = new_head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 2
    # 3
 
# Deleting a node from original linked list
head.next = third
 
# Print original linked list
current_node = head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 3
 
# Print shallow copy
current_node = new_head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 3

In this example, we define a Node class to represent each element of the linked list. We create a linked list with three nodes and set the references accordingly. To create a shallow copy, we assign the head node to a new variable new_head. Both variables point to the same memory location, so any modification to one will reflect in the other. When we delete a node from the original linked list, it affects both the original and shallow copy.

Example 2: Creating Deep Copy

The second example demonstrates creating a deep copy of a linked list. Since our initial linked list was modified, we will first re-initialize it, then perform the deepcopy operation Here’s the example:

# Re-initializing the Linked List
head = Node(1)
second = Node(2)
third = Node(3)
 
head.next = second
second.next = third
 
# Deep copy
new_head = copy.deepcopy(head)
 
# Print original linked list
current_node = head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 2
    # 3
 
# Print deep copy
current_node = new_head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 2
    # 3
 
# Deleting a node from original linked list
head.next = third
 
# Print original linked list
current_node = head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 3
 
# Print deep copy
current_node = new_head
while current_node:
    print(current_node.value)
    current_node = current_node.next
    # 1
    # 2
    # 3

In this example, we use the deepcopy() function from the copy module to create a deep copy of the linked list. The deep copy creates a new linked list with separate nodes, so the modifications to one list don’t affect the other. Even after deleting a node from the original linked list, the deep copy remains unchanged.

Video, Further Resources & Summary

Do you need more explanations on making a copy of a linked list in Python? Then you should have a look at the following YouTube video of the Statistics Globe YouTube channel.

The YouTube video will be added soon.

Furthermore, you could have a look at some of the other tutorials on Statistics Globe:

• List in Python (Beginner & Advanced)
• Circular Doubly Linked List in Python
• Delete Node in Linked List in Python (Example)
• Loop Through List of Strings in Python
• Loop Over Range List in Python
• Loop Through List of Integers in Python

This post has shown how to make a copy of a linked list in Python using both shallow and deep copy methods. In case you have further questions, you may leave a comment below.

This page was created in collaboration with Ömer Ekiz. Have a look at Ömer’s author page to get more information about his professional background, a list of all his tutorials, as well as an overview of his other tasks on Statistics Globe.