Python - sorted() vs sort() Usage

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What Are sorted() and sort() Functions?

Python provides two primary methods for sorting: sored() and sort(). While both are used to arrange elements in a particular order, they function in distinct ways and have different applications./. Understanding these differences and knowing when to use each can significantly enhance your efficiency in writing Python code.

Differences Between sorted() and sort()

sorted() is a built-in Python function that returns a new list containing all items from the iterable in ascending order. The original iterable remains unchanged. This function can be used with any iterable, including lists, tuples, and dictionaries.

sort(), on the other hand, is a method specific to lists. It sorts the list in place, meaning the original list is modified, and no new list is created. This method cannot be used with other iterable types.

Examples

Before we dive into the code, both sorted() and sort() in Python take similar parameters to control how the sorting is performed. Here’s a detailed look at the parameters for each:

  • Parameters for sorted() :
    • iterable: The sequence or collection to be sorted (e.g., list, tuple, dictionary, etc.).
    • key (optional): A function that serves as a key for the sort comparison. The function is applied to each element before comparison.
    • reverse (optional): A boolean value. If True, the sorted list is in descending order. The default is False (ascending order).
  • Parameters for sort() :
    • key (optional): A function that serves as a key for the sort comparison. The function is applied to each element before comparison.
    • reverse (optional): A boolean value. If True, the list is sorted in descending order. The default is False (ascending order).

Examples using sorted()

  • Basic usage with only the iterable:
words = ["banana", "orange", "date", "apple"]
print("Original list:", words)

sorted_words = sorted(words)
print("Sorted list:", sorted_words)

# Original list: ['banana', 'orange', 'date', 'apple']
# Sorted list: ['apple', 'banana', 'date', 'orange']
  • Using the key argument:
words = ["banana", "orange", "date", "apple"]
print("Original list:", words)

sorted_words = sorted(words, key=len)
print("Sorted by length:", sorted_words)

# Original list: ['banana', 'orange', 'date', 'apple']
# Sorted by length: ['date', 'apple', 'banana', 'orange']
  • Using the reverse argument:
words = ["banana", "orange", "date", "apple"]
print("Original list:", words)

sorted_words_desc = sorted(words, reverse=True)
print("Sorted list (descending):", sorted_words_desc)

# Original list: ['banana', 'orange', 'date', 'apple']
# Sorted list (descending): ['orange', 'date', 'banana', 'apple']
  • Sorting a tuple:
words = ("banana", "orange", "date", "apple")
print("Original tuple:", words)

sorted_tuple = sorted(words)
print("Sorted list:", sorted_tuple)

# Original tuple: ('banana', 'orange', 'date', 'apple')
# Sorted list: ['apple', 'banana', 'date', 'orange']
  • Sorting a dictionary:
dictionary = {"apple": 3, "banana": 2, "cherry": 5, "date": 1}
print("Original dictionary: ", dictionary)

sorted_by_keys = sorted(dictionary.items())
print("Sorted dictionary by keys:", sorted_by_keys)

# Original dictionary:  {'apple': 3, 'banana': 2, 'cherry': 5, 'date': 1}
# Sorted dictionary by keys: [('apple', 3), ('banana', 2), ('cherry', 5), ('date', 1)]

Examples Using sort()

Note: The original list will be modified. You can try printing the list before the sort() call to see its state before sorting.

  • Basic usage with only the list:
words = ["banana", "orange", "date", "apple"]
print("Before sort(): ", words)

words.sort()
print("After sort(): ", words)

# Before sort():  ['banana', 'orange', 'date', 'apple']
# After sort():  ['apple', 'banana', 'date', 'orange']
  • Using the key argument:
words = ["banana", "orange", "date", "apple"]
print("Before sort(): ", words)

words.sort(key=len)
print("After sorted by length:", words)

# Before sort():  ['banana', 'orange', 'date', 'apple']
# After sorted by length: ['date', 'apple', 'banana', 'orange']
  • Using the reverse argument:
words = ["banana", "orange", "date", "apple"]
print("Before sort(): ", words)

words.sort(reverse=True)
print("After sorted list (descending):", words)

# Before sort():  ['banana', 'orange', 'date', 'apple']
# After sorted list (descending): ['orange', 'date', 'banana', 'apple']
  • Sorting a tuple:

Tuples are immutable, meaning they cannot be changed once created. Since sort() modifies the list in place, it is not possible to use sort() with tuples.

words = ("banana", "orange", "date", "apple")

words.sort()
print(words)

# ---------------------------------------------------------------------------
# AttributeError                            Traceback (most recent call last)
# <ipython-input-4-d655670a766a> in <cell line: 3>()
#       1 words = ("banana", "orange", "date", "apple")
#       2
# ----> 3 words.sort()
#       4
#       5 print(words)

# AttributeError: 'tuple' object has no attribute 'sort'
  • Sorting a dictionary:

Dictionaries do not have a sort() method. Sorting must be done on their items, converted to a list first if needed.

dictionary = {"apple": 3, "banana": 2, "cherry": 5, "date": 1}

dictionary.sort()
print(dictionary)

# ---------------------------------------------------------------------------
# AttributeError                            Traceback (most recent call last)
# <ipython-input-13-988de0b42198> in <cell line: 3>()
#       1 dictionary = {"apple": 3, "banana": 2, "cherry": 5, "date": 1}
#       2
# ----> 3 dictionary.sort()
#       4 print(dictionary)

# AttributeError: 'dict' object has no attribute 'sort'

Resources

How to Use sorted() and .sort() in Python by Real Python

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