Python 101: sort() vs sorted() in Python

In Python sort() vs sorted()

When sorting lists in Python, you can use either the sort() method or the sorted() function. Below is a detailed comparison of these two approaches, including code examples, tips, and warnings.

Comparison Table

Code Examples

Using sort()

The sort() method sorts a list in place, meaning it modifies the original list and does not return a new list.

# Example list
my_list = [4, 2, 3, 1]

# Using sort()
my_list.sort()
print(my_list)  # Output: [1, 2, 3, 4]

Using sorted()

The sorted() function returns a new sorted list from the elements of any iterable.

# Example list
my_list = [4, 2, 3, 1]

# Using sorted()
sorted_list = sorted(my_list)
print(sorted_list)  # Output: [1, 2, 3, 4]

# Original list remains unchanged
print(my_list)  # Output: [4, 2, 3, 1]

Tips

• Choosing Between sort() and sorted():
  • Use sort() if you need to sort a list in place and do not need to retain the original order.
  • Use sorted() if you need a sorted version of the iterable but also need to keep the original order intact.
• Custom Sorting:
  • Both sort() and sorted() accept a key parameter for custom sorting. For example, sorting by the length of strings:

    my_list = ['apple', 'banana', 'cherry']
    my_list.sort(key=len)
    print(my_list)  # Output: ['apple', 'cherry', 'banana']
    

Warnings

• Modifying Original List:
  • The sort() method modifies the original list. If you need to keep the original list unchanged, use sorted().
• Performance Considerations:
  • For large datasets, consider the overhead of creating a new list with sorted() versus modifying the original list with sort().