Python Tutorials · Python Lists

Sort Lists

Learn all about Sort Lists in this comprehensive tutorial.

5 min read beginner

•List objects have a sort() method that will sort the list alphanumerically, ascending, by default:
•To sort descending, use the keyword argument reverse = True:
•You can also customize your own function by using the keyword argument key = function.
•By default the sort() method is case sensitive, resulting in all capital letters being sorted before lower case letters:
•What if you want to reverse the order of a list, regardless of the alphabet?

Sort List Alphanumerically

List objects have a sort() method that will sort the list alphanumerically, ascending, by default:

python

thislist = ["orange", "mango", "kiwi", 
  "pineapple", "banana"]thislist.sort()
print(thislist)

python

thislist = [100, 50, 65, 82, 23]thislist.sort()
print(thislist)

To sort descending, use the keyword argument reverse = True:

python

thislist = ["orange", "mango", "kiwi", 
  "pineapple", "banana"]thislist.sort(reverse = True)
print(thislist)

python

thislist = [100, 50, 65, 82, 23]thislist.sort(reverse = True)
print(thislist)

You can also customize your own function by using the keyword argument key = function.

The function will return a number that will be used to sort the list (the lowest number first):

python

def myfunc(n):  return abs(n - 50)thislist = [100, 50, 65, 82, 23]thislist.sort(key = 
  myfunc)print(thislist)

By default the sort() method is case sensitive, resulting in all capital letters being sorted before lower case letters:

python

thislist = ["banana", "Orange", "Kiwi", "cherry"]thislist.sort()print(thislist)

Luckily we can use built-in functions as key functions when sorting a list.

So if you want a case-insensitive sort function, use str.lower as a key function:

python

thislist = ["banana", "Orange", "Kiwi", "cherry"]thislist.sort(key 
  = str.lower)print(thislist)

What if you want to reverse the order of a list, regardless of the alphabet?

The reverse() method reverses the current sorting order of the elements.

python

thislist = ["banana", "Orange", "Kiwi", "cherry"]thislist.reverse()print(thislist)

2 questions

Which of the following is true about Sort Lists?

It is strictly typedIt is evaluated at runtimeIt requires explicit memory managementIt is deprecated

What is the most common pitfall when working with Sort Lists?

SyntaxErrorIndentationErrorNameErrorTypeError

Answer all questions to submit.