Difference between sort and sorted functions in Python

Why Sort Lists?

We often need to sort the elements of a list for various reasons like searching for elements, merging elements, optimizing list performance and readability etc. In Python we can use 'sort' and 'sorted' functions to sort a list. While both functions can be used to sort a list there are some differences in the usage of these functions that should be kept in mind before using one over the other.

Sorted

Sorted function (built-in) takes a list as argument (along with other optional arguments) and returns a new list with elements of original list sorted in ascending or descending order.

 

    Output:

To sort the list in descending order, add reverse = True with the list argument. 

    Output:

Sort

Sort function/ method will sort the original list without the need of creating a new list. It is applied on the list object rather than taking the list as an argument.

    Output:

Keep in mind that you should not assign the sort function to a new list as it will not return anything. 

    Output:

Sorting string literals

We can also use sorted function to sort string literals. By default, it sorts capital letters first and then small case letters in alphabetical order. To sort a string without considering capitalization, we can use a keyword argument called casefold.

    Output:

    [' ', ' ', ' ', ' ', ' ', ' ', ' ', 'T', 'a', 'a', 'a', 'b', 'd', 'd', 'd', 'd', 'e', 'e', 'g', 'i', 'i', 'o', 'o', 'o', 'o', 'o', 's', 's', 't', 't', 'u', 'y', 'y']

using casefold:

    Output:

[' ', ' ', ' ', ' ', ' ', ' ', ' ', 'a', 'a', 'a', 'b', 'd', 'd', 'd', 'd', 'e', 'e', 'g', 'i', 'i', 'o', 'o', 'o', 'o', 'o', 's', 's', 'T', 't', 't', 'u', 'y', 'y']

This case-insensitive sorting is particularly useful when you have a list of names, items etc. and you need to sort them alphabetically.

names = ["Jordan", "jane", "Peter", "Ian", "Eric", "ana"]
names.sort()
print("Case sensitive sorting: ", names)
names.sort(key = str.casefold)
print("Case insensitive sorting: ", names)

Output:

Case sensitive sorting:  ['Eric', 'Ian', 'Jordan', 'Peter', 'ana', 'jane']

Case insensitive sorting:  ['ana', 'Eric', 'Ian', 'jane', 'Jordan', 'Peter']

Note: we used sort twice in above code snippet which means first we sorted the original list and then we sorted the case sensitive sorted list from first sort operation.