What is the difference between "append" and "extend" in Python?

Question

Jayant Kumar · Accepted Answer

Table of Contents
Introduction
In Python, lists are a versatile data structure that allows you to store and manipulate collections of items. Two common methods used to modify lists are append and extend. Although both methods add elements to a list, they do so in different ways. Understanding the differences between append and extend is crucial for effective list manipulation in Python. This article will clarify how each method works and provide practical examples to illustrate their usage.
Key Differences Between append and extend
1. Functionality

**append**: The append method adds its argument as a single element to the end of the list. This means that the argument is treated as a single entity, regardless of its type (e.g., whether it is a number, string, or another list).
**extend**: The extend method iterates over its argument and adds each element to the end of the list. The argument must be an iterable (such as a list, tuple, or set), and its elements are added individually to the list.

Example:
# Using append
my_list = [1, 2, 3]
my_list.append([4, 5])  # Appends the list [4, 5] as a single element
print(my_list)  # Output: [1, 2, 3, [4, 5]]

# Using extend
my_list = [1, 2, 3]
my_list.extend([4, 5])  # Adds each element of [4, 5] to the list
print(my_list)  # Output: [1, 2, 3, 4, 5]

2. Argument Type

**append**: Accepts a single argument of any data type and adds it as a single element.
**extend**: Accepts an iterable (e.g., list, tuple, or set) and adds each element of the iterable to the list.

Example:
# Append with different types
my_list = [1, 2]
my_list.append(3)      # Appends the integer 3
my_list.append([4, 5]) # Appends the list [4, 5] as a single element
print(my_list)  # Output: [1, 2, 3, [4, 5]]

# Extend with different iterables
my_list = [1, 2]
my_list.extend((3, 4))  # Adds each element of the tuple (3, 4) to the list
print(my_list)  # Output: [1, 2, 3, 4]

my_list.extend({5, 6})  # Adds each element of the set {5, 6} to the list
print(my_list)  # Output: [1, 2, 3, 4, 5, 6]

3. Use Cases

**append**: Use append when you need to add a single item to the end of a list, regardless of its type. This method is ideal for adding elements where you don’t need to unpack or decompose the item.
**extend**: Use extend when you want to add multiple items to a list from another iterable. This method is suitable for merging lists or adding elements from iterable collections.

Practical Examples
Example : Using append to Add a Single Item
python
# Initial list
numbers = [1, 2, 3]

# Appending an integer
numbers.append(4)
print(numbers)  # Output: [1, 2, 3, 4]

# Appending another list as a single element
numbers.append([5, 6])
print(numbers)  # Output: [1, 2, 3, 4, [5, 6]]

Example : Using extend to Add Multiple Items
# Initial list
numbers = [1, 2, 3]

# Extending with a list
numbers.extend([4, 5])
print(numbers)  # Output: [1, 2, 3, 4, 5]

# Extending with a tuple
numbers.extend((6, 7))
print(numbers)  # Output: [1, 2, 3, 4, 5, 6, 7]

Conclusion
The append and extend methods in Python both serve to add elements to a list, but they do so in different ways. append adds its argument as a single element, while extend iterates over its argument and adds each element individually. By understanding these differences, you can choose the appropriate method based on whether you need to add single items or multiple items from an iterable to your list.

What is the difference between "append" and "extend" in Python?

Table of Contents

Introduction

Key Differences Between `append` and `extend`

1. Functionality

Example:

2. Argument Type

Example:

3. Use Cases

Practical Examples

Example : Using `append` to Add a Single Item

Example : Using `extend` to Add Multiple Items

Conclusion

Similar Questions