Python sorted() Function

The sorted() function returns a new sorted list from any iterable. It works with lists, tuples, strings, dictionaries, sets, and other iterable objects. Use it when you want sorted output without changing the original data.

Tested on: Python 3.13.3; kernel 6.14.0-37-generic.

Quick answer: sort vs sorted in Python

Use sorted(data) when you want a new sorted list. Use data.sort() only when data is a list and you want to modify it in place.

numbers = [3, 1, 4, 1, 5]

print(sorted(numbers))
print(numbers)

numbers.sort()
print(numbers)

The first print shows [1, 1, 3, 4, 5]. The second still shows the original order because sorted() does not change the list. After sort(), the list itself is sorted in place.

Python sorted() quick reference

For deeper list-only or dictionary-only examples, see Python sort list, sort dictionary by key, and sort dictionary by value.

What is sorted() in Python?

sorted() is a built-in function. It accepts any iterable, returns a new list, and does not modify the original object. You can control sorting with key and reverse.

Even when you sort a tuple or string, the result is always a list.

Python sorted() syntax

Syntax: sorted(iterable, /, *, key=None, reverse=False)

• iterable is required.
• key is optional. It names a function called once per item.
• reverse is optional. Set it to True for descending order.
• The return value is always a list.

See the built-in sorted() documentation for the full signature.

Basic sorted() example

numbers = [3, 1, 4, 1, 5]
original = numbers.copy()

sorted_numbers = sorted(numbers)

print(sorted_numbers)
print(numbers)
print(numbers is sorted_numbers)

You get a new sorted list, the original list stays unchanged, and the two list objects are different.

sort() vs sorted() in Python

The Python tutorial on lists describes list.sort() as an in-place sort. The sorting HOWTO explains that sorted() builds a new sorted list instead.

When to use sorted()

Use sorted() when:

• You want to keep the original iterable unchanged.
• You are sorting a tuple, string, set, dictionary, generator, or other non-list iterable.
• You need a new sorted list for an expression or return value.
• You are chaining or nesting sorts inside another call.

When to use list.sort()

Use list.sort() when:

• You already have a list.
• You want to modify that list in place.
• You do not need the previous order.
• You want to avoid creating a second list in memory.

scores = [88, 72, 95]
result = scores.sort()

print(scores)
print(result)

After sort(), scores is sorted. result is None, not a sorted list.

sorted() with reverse=True

Use reverse=True for descending order.

numbers = [3, 1, 4, 1, 5]

print(sorted(numbers, reverse=True))

For simple numeric descending sorts, reverse=True is clearer than tricks such as key=lambda x: -x.

sorted() with key function

The key argument controls what value is compared for each item. Python calls the key function once per element.

words = ["Banana", "apple", "Cherry"]

print(sorted(words))
print(sorted(words, key=str.lower))
print(sorted(words, key=len))

Default sorting is case-sensitive. key=str.lower compares case-insensitively. key=len sorts by string length.

The sorting HOWTO explains how key functions work in detail.

Sort strings with sorted()

sorted("python") returns a list of characters, not a string.

text = "python"

print(sorted(text))
print("".join(sorted(text)))

Use "".join(sorted(text)) when you need a sorted string result.

Sort tuple with sorted()

sorted() on a tuple returns a list. Convert back to a tuple only if you need tuple output.

data = (4, 1, 3)

sorted_list = sorted(data)
sorted_tuple = tuple(sorted(data))

print(sorted_list)
print(sorted_tuple)
print(type(sorted_list))

For more on tuples, see Python tuple.

Sort dictionary with sorted()

sorted(my_dict) sorts dictionary keys. It does not sort values.

data = {"key3": 2, "key1": 5, "key2": 3}

print(sorted(data))
print(sorted(data.items()))
print(sorted(data.items(), key=lambda item: item[1]))

The first line prints sorted keys. The second prints (key, value) pairs sorted by key. The third sorts pairs by value.

For full walkthroughs, see the dedicated dictionary sorting articles linked at the start of this page.

Sort list of dictionaries

Use a key function to sort by one field.

from operator import itemgetter

users = [
    {"name": "Bob", "age": 30},
    {"name": "Ann", "age": 30},
    {"name": "Cal", "age": 25},
]

by_age = sorted(users, key=lambda user: user["age"])
by_name = sorted(users, key=itemgetter("name"))

print(by_age[0]["name"])
print(by_name[0]["name"])

The first sort returns Cal because age 25 comes first. The second returns Ann when sorting by name.

Sort list of lists

Sort rows by a column with key=lambda row: row[index].

rows = [[2, 34], [1, 43], [3, 56]]

print(sorted(rows, key=lambda row: row[1]))

The rows are ordered by the second column: 34, then 43, then 56.

Stable sorting in Python

Python sorting is stable. Items with equal sort keys keep their original relative order.

data = [("a", 1), ("b", 2), ("c", 1)]

print(sorted(data, key=lambda item: item[1]))

Both ("a", 1) and ("c", 1) have key 1, and "a" stays before "c" because it appeared first in the original list.

Sort by multiple criteria

Return a tuple from the key function to sort by more than one field.

users = [
    {"age": 30, "name": "Bob"},
    {"age": 30, "name": "Ann"},
    {"age": 25, "name": "Cal"},
]

print(sorted(users, key=lambda user: (user["age"], user["name"])))

Python compares age first, then name when ages tie. Cal comes first, then Ann, then Bob.

Summary

sorted() returns a new sorted list from any iterable. list.sort() modifies a list in place and returns None. Use reverse=True for descending order and key= for custom sorting. Tuple keys handle multiple criteria.

References

• Python built-in sorted()
• Python list sort() method
• Sorting HOWTO
• Python tutorial: more on lists