sorted() overview
The Python sorted() function sorts an iterable in a specific order, either ascending or descending and returns it as a sorted list. The difference to the sort method of lists is that sort() doesn't return anything and changes the original list instead.
sorted() lists
To sort a list, use the sorted() function or the list.sort() method. The difference is that sorted() returns a new list.
# sorted() lists
myList = [1, 5, 9, 4]
Sorted = sorted(myList)
Reversed = sorted(myList, reverse=True)
print(Sorted)
print(Reversed)
The sorted and reversed lists are returned.
[1, 4, 5, 9]
[9, 5, 4, 1]
sorted() strings
If a string is passed to the sorted() function a list sorted in alphabetical order is returned. The order can be reversed by using the reverse flag.
# sorted() strings
myString = 'Python'
SortedString = sorted(myString)
ReversedString = sorted(myString, reverse=True)
print(SortedString)
print(ReversedString)
The sorted and reversed string are returned.
['P', 'h', 'n', 'o', 't', 'y']
['y', 't', 'o', 'n', 'h', 'P']
sorted() using key
To modify the behaviour of the sorted() function, it's possible to pass in a key as optional argument.
For example we can pass in the len() function as key argument to sort the list based on the length of each element.
# sorted() using key function
myList = ['abc', 'a', 'ab', 'abcd']
# sort list by length of element
Sorted = sorted(myList, key=len)
print(Sorted)
The list is sorted by the length of each element. The key argument can be combined with the reverse argument to show to longest element first.
['a', 'ab', 'abc', 'abcd']
sorted() on nested objects
If a nested object like a nested tuple is passed to the sorted() function, it sorts the elements based on the first key.
# SORTED() ON NESTED OBJECTS
myNestedTuple = [('Mike', 12, 18), ('Dave', 4, 25), ('Anna', 22, 8)]
Sorted = sorted(myNestedTuple)
print(Sorted)
The elements are sorted in order of the first key, in this case, the name. To modify this behavior use the key argument.
[('Anna', 22, 8), ('Dave', 4, 25), ('Mike', 12, 18)]
sorted() syntax
The syntax of the sorted() function is:
sorted(iterable[, key=None, reverse=False])
sorted() arguments
The sorted() function accepts between 1 and 3 arguments:
| argument |
required |
description |
| iterable |
required |
the iterable to be sorted (string, tuple, list, set, dictionary, ...) |
| reverse |
optional |
If True, sorted list is reversed. Default: False |
| key |
optional |
function to be used as key for the sorting. Default None |
If less than one or more than three arguments are passed, a TypeError exception is raised.
sorted() return values
The sorted() function returns a sorted list. Even when another object type is passed to the sorted() function, the return value will always be a list.
related functions
The sorted() function is related to the sort() method of lists. While list.sort() doesn't return anything, the sorted() function returns a new list and doesn't change the passed iterable.