In this tutorial, we will look at sorting lists in detail. In particular, we will cover:

• The sorted() function
• Custom sorting by passing key function in sorted()
• The difference between sorted() and list.sort()

Let's get started!

The sorted() function

The easiest way to sort is with the sorted(list) function, which takes a list and returns a new list with those elements in sorted order. The original list is not changed.

type=codeblock|id=py3_sorting|autocreate=python3
a = [5, 1, 4, 3]
print(sorted(a))  ## [1, 3, 4, 5]
print(a)  ## [5, 1, 4, 3]

It's most common to pass a list into the sorted() function, but in fact it can take as input any sort of iterable collection. The older list.sort() method is an alternative detailed below. The sorted() function seems easier to use compared to sort(), so I recommend using sorted().

The sorted() function can be customized through optional arguments. The sorted() optional argument reverse=True, e.g. sorted(list, reverse=True), makes it sort backwards.

type=codeblock|id=py3_sorting_reverse|autocreate=python3
strs = ['aa', 'BB', 'zz', 'CC']
print(sorted(strs))  ## ['BB', 'CC', 'aa', 'zz'] (case sensitive)
print(sorted(strs, reverse=True))   ## ['zz', 'aa', 'CC', 'BB']