python tutorial

Python Set

Learn more about Python, one of the world’s most versatile and popular programming languages.

Python sets are just an unordered collection of items which does not allow duplicate elements. Python set is used when data structure needs to only have unique elements in it. Python sets also allow mathematical operations like union, intersection, and difference to find common and unique items between two sets.

Using Sets in Python

Let’s dive into the Python set and understand how to use them as a data type. Below is an example that creates two sets as a wishlist of movies to watch for two different people. Sets are created using curly brackets. As you can see, Python sets do not allow duplicate values and will remove it automatically from a set.

Code Example

# movies to watch for john
john_movies_wishlist = {'Titanic', 'Die Hard', 'Pulp Fiction', 'Forrest Gump', 'Parasite', 'Die Hard'}
# movies to watch for adan
adam_movies_wishlist = {'Psycho', 'The Lion King', 'Titanic', 'Parasite', 'Gladiator', 'Coco'}
# note: duplicate items from a set are automatically removed
print(john_movies_wishlist)
{'Parasite', 'Die Hard', 'Pulp Fiction', 'Forrest Gump', 'Titanic'}
# note: items do not appear in the same order as written
print(adam_movies_wishlist)
{'Parasite', 'Gladiator', 'Psycho', 'The Lion King', 'Titanic', 'Coco'}

Mathematical Operations on Python Sets

Let’s use common mathematical set operations like union, intersection and difference on our sets. Union will combine all the elements from both sets, intersection will provide all the elements present in both sets and difference will provide all the elements unique to each set.

Let’s do the following set operations on our movies wishlist for john and adam.

Movies in John’s wishlist but not Adam’s – using - operator
Movies in either John’s or Adam’s wishlist or in both of their wishlist – using | operator
Movies in both John’s and Adam’s wishlist – using & operator
Movies unique in John’s and Adam’s wishlist but not both – using ^ operator

Code Example

# movies to watch for john
john_movies_wishlist = {'Titanic', 'Die Hard', 'Pulp Fiction', 'Forrest Gump', 'Parasite', 'Die Hard'}
# movies to watch for adam
adam_movies_wishlist = {'Psycho', 'The Lion King', 'Titanic', 'Parasite', 'Gladiator', 'Coco'}
# note: duplicate items from a set are automatically removed
print(john_movies _wishlist)
{'Parasite', 'Titanic', 'Pulp Fiction', 'Forrest Gump', 'Die Hard'}
# note: items do not appear in the same order as written
print(adam_movies_wishlist)
{'Coco', 'Parasite', 'Gladiator', 'Titanic', 'The Lion King', 'Psycho'}
# movies in John’s wishlist but not Adam’s
print(john_movies_wishlist - adam_movies_wishlist)
{'Pulp Fiction', 'Die Hard', 'Forrest Gump'}
# movies in either John's wishlist or Adam's wishlist or in both wishlists
print(john_movies_wishlist | adam_movies_wishlist)
{'Coco', 'Parasite', 'Gladiator', 'Titanic', 'Pulp Fiction', 'The Lion King', 'Forrest Gump', 'Psycho', 'Die Hard'}
# movies in both John's wishlist and Adam's wishlist
print(john_movies_wishlist & adam_movies_wishlist)
{'Titanic', 'Parasite'}
# movies in either John's wishlist or Adam's wishlist but not in both
print(john_movies_wishlist ^ adam_movies_wishlist)
{'Coco','Gladiator', 'The Lion King', 'Pulp Fiction', 'Forrest Gump', 'Psycho', 'Die Hard'}

Learn Python Today

Get hands-on experience writing code with interactive tutorials in our free online learning platform.

Free and fun
Designed for beginners
No downloads or setup required

Get Started