Append() vs Extend(): A Detailed Comparison for Python Lists

The list techniques append and extend behave differently. Here is a detailed comparison append Vs. extend in Python. The append method adds a single element to the end of the list. The extend method adds multiple elements by appending iterable(each item). Both techniques serve to change lists in Python.

Python Lists: append Vs extend

1. append()

• Purpose: Adds a single element (object) to the end of the list.
• Behavior: Treats the argument as a single entity and adds it to the list as-is.
• Syntax: list.append(element)

Example:

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

2. extend()

• Purpose: Adds all elements of an iterable (e.g., list, tuple, string) to the end of the list.
• Behavior: Iterates the argument and adds each element individually.
• Syntax: list.extend(iterable)

Example:

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

Key Differences

Extra Examples

Appending a string:

my_list = [1, 2, 3] 
my_list.append("hello") 
print(my_list) 
# Output: [1, 2, 3, 'hello'] 

Here, the entire string "hello" is added as a single element.

Extending with a string:

my_list = [1, 2, 3] 
my_list.extend("hello") 
print(my_list) 

# Output: [1, 2, 3, 'h', 'e', 'l', 'l', 'o']. 
Each character of the string "hello" is added separately. Each character becomes a separate element.

When to Use append vs. extend

• Use the append to add a single item. You can add an entire object, like another list, as a single element.
• Use the extend to concatenate of another iterable. It could be a list, tuple, or string. You add it to the end of your list.