sorted()

Takes in an iterator object, such as a list, tuple, dictionary, set, or string, and sorts it according to a parameter.

Syntax

sorted(iterable, key=None, reverse=False)

The key and reverse parameters are optional, and will default to None and False. False sorts ascending, and True descending. The key takes an input function to determine the comparison key.

Example 1

sorted() can be used on either numbers or letters, but not on a combination of the two:

my_list = ["beta", "epsilon", "alpha", "delta", "gamma"]

new_list = sorted(my_list)

print(new_list)
# Output: ['alpha', 'beta', 'delta', 'epsilon', 'gamma']

my_list = [7,2,3,5,1,4,6]

new_list = sorted(my_list)

print(new_list)
# Output: [1, 2, 3, 4, 5, 6, 7]

Example 2

Changing the reverse parameter changes the order of the sort:

my_list = [7,2,3,5,1,4,6]

new_list = sorted(my_list, reverse=True)

print(new_list)
# Output: [7, 6, 5, 4, 3, 2, 1]

Example 3

When reversed is False, sorted() will sort numbers from low to high, and letters alphabetically. However, capital letters will come before lowercase letters. In order to sort all objects with the same key, use a function with the key parameter:

my_string = "bCEad"

after_sorted = sorted(my_string)

print(after_sorted)
# Output: ['C', 'E', 'a', 'b', 'd']

after_sorted = sorted(my_string, key=str.lower)

print(after_sorted)
# Output: ['a', 'b', 'C', 'd', 'E']

Example 4

The key parameter can also be used to sort by other comparisons, such as length:

my_list = ["aaa", "bb", "c"]

my_sorted_list = sorted(my_list)

print(my_sorted_list)
# Output: ['aaa', 'bb', 'c']

my_sorted_list = sorted(my_list, key=len)

print(my_sorted_list)
# Output: ['c', 'bb', 'aaa']

Example 5

The key parameter can even take in custom functions:

def sorting_func(i):
  return i - i**2

my_list = [2,1,4,3]

my_sorted_list = sorted(my_list)

print(my_sorted_list)
# Output: [1, 2, 3, 4]

my_sorted_list = sorted(my_list, key=sorting_func)

print(my_sorted_list)
# Output: [4, 3, 2, 1]