Of course! Sorting strings in Python is a common task, and Python provides powerful and flexible ways to do it. The main tool you'll use is the built-in sorted() function, and the .sort() method for lists.

Here’s a complete guide, from the basics to more advanced sorting techniques.

The Basics: Using sorted() and .sort()

There are two primary ways to sort strings:

• sorted(my_string): Returns a new sorted list of the characters in the string. The original string is unchanged.
• my_list_of_strings.sort(): Sorts a list of strings in-place, modifying the original list. This method does not return anything.

Example 1: Sorting the characters within a single string

my_string = "python"
# sorted() returns a new list of sorted characters
sorted_chars = sorted(my_string)
print(f"Original string: {my_string}")
print(f"Sorted list of characters: {sorted_chars}")
# Output: Sorted list of characters: ['h', 'n', 'o', 'p', 't', 'y']
# To get back a sorted string, you must join the list
sorted_string = "".join(sorted_chars)
print(f"Sorted string: {sorted_string}")
# Output: Sorted string: hnopty

Example 2: Sorting a list of strings

languages = ["Python", "Java", "C++", "Ruby", "Go"]
# sorted() returns a new sorted list
sorted_languages = sorted(languages)
print(f"Original list: {languages}")
print(f"New sorted list: {sorted_languages}")
# Output: New sorted list: ['C++', 'Go', 'Java', 'Python', 'Ruby']
# The .sort() method sorts the list in-place
languages.sort()
print(f"List after .sort(): {languages}")
# Output: List after .sort(): ['C++', 'Go', 'Java', 'Python', 'Ruby']

Advanced Sorting with the key Argument

This is where Python's sorting power really shines. The key argument allows you to specify a function to be called on each element prior to making comparisons. This means you can sort by custom criteria.

Key Functions for Common String Sorting Tasks

A) Case-Insensitive Sorting

By default, Python sorts uppercase letters before lowercase letters ('A' < 'a').

words = ["apple", "Banana", "cherry", "Date"]
# Default sort (A-Z, then a-z)
default_sort = sorted(words)
print(f"Default sort: {default_sort}")
# Output: Default sort: ['Banana', 'Date', 'apple', 'cherry']
# Case-insensitive sort
case_insensitive_sort = sorted(words, key=str.lower)
print(f"Case-insensitive sort: {case_insensitive_sort}")
# Output: Case-insensitive sort: ['apple', 'Banana', 'cherry', 'Date']

B) Sorting by Length

You can sort strings based on how many characters they have.

words = ["cat", "elephant", "dog", "mouse"]
# Sort by length (shortest to longest)
by_length = sorted(words, key=len)
print(f"Sorted by length: {by_length}")
# Output: Sorted by length: ['cat', 'dog', 'mouse', 'elephant']
# Sort by length (longest to shortest)
by_length_desc = sorted(words, key=len, reverse=True)
print(f"Sorted by length (descending): {by_length_desc}")
# Output: Sorted by length (descending): ['elephant', 'mouse', 'cat', 'dog']

C) Sorting by a Custom Logic (Lambda Function)

Imagine you have filenames and want to sort them by their number.

files = ["file10.txt", "file2.txt", "file1.txt"]
# Default sort will be lexicographical, not numerical
default_sort = sorted(files)
print(f"Default sort: {default_sort}")
# Output: Default sort: ['file1.txt', 'file10.txt', 'file2.txt'] (Wrong!)
# Correct sort: extract the number and sort by it
# We use a lambda function to get the number part and convert it to an int
numerical_sort = sorted(files, key=lambda s: int(s.split('e')[-1].split('.')[0]))
print(f"Numerical sort: {numerical_sort}")
# Output: Numerical sort: ['file1.txt', 'file2.txt', 'file10.txt']

In-Place vs. New List: A Quick Summary

Rule of Thumb:

• Use sorted() when you need a new sorted list and want to keep the original intact.
• Use .sort() when you are sure you don't need the original order anymore and want to save memory (since it doesn't create a new list).

Complete Example: Sorting a Complex List of Files

Let's put it all together. Imagine you have a list of log files and you want to sort them by their timestamp.

log_files = [
    "app_2025-10-26.log",
    "app_2025-10-25.log",
    "error_2025-10-26.log",
    "app_2025-10-24.log",
    "error_2025-10-25.log"
]
# Goal: Sort by date, newest first.
# The date is the part after the last underscore.
# We'll use a lambda to extract the date string
# The `reverse=True` is for newest first (descending order)
sorted_logs = sorted(log_files, key=lambda s: s.split('_')[-1], reverse=True)
print("Original log files:")
for log in log_files:
    print(f"  - {log}")
print("\nSorted log files (newest first):")
for log in sorted_logs:
    print(f"  - {log}")
# Output:
# Sorted log files (newest first):
#   - app_2025-10-26.log
#   - error_2025-10-26.log
#   - app_2025-10-25.log
#   - error_2025-10-25.log
#   - app_2025-10-24.log

Key Takeaways

1. sorted() is for getting a new sorted list.
2. .sort() is for sorting a list in-place.
3. Use the key argument for custom sorting logic.
4. key=str.lower is your best friend for case-insensitive sorting.
5. key=len is perfect for sorting by length.
6. lambda functions are great for creating simple, one-time key functions for complex rules.