Menu
×
Get Certified Upgrade Academy Spaces Practice Get Certified Upgrade Academy Spaces Practice
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP W3.CSS C C++ C# HOW TO BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS DSA TYPESCRIPT ANGULAR ANGULARJS GIT POSTGRESQL MONGODB ASP AI R GO KOTLIN SWIFT SASS VUE GEN AI SCIPY AWS CYBERSECURITY DATA SCIENCE INTRO TO PROGRAMMING INTRO TO HTML & CSS BASH RUST TOOLS

Python Tutorial

Python HOME Python Intro Python Get Started Python Syntax
Syntax Statements Code Challenge
Python Output
Print Text Print Numbers Code Challenge
Python Comments
Comments Code Challenge
Python Variables
Python Variables Variable Names Assign Multiple Values Output Variables Global Variables Variable Exercises Code Challenge
Python Data Types
Data Types Code Challenge
Python Numbers
Numbers Code Challenge
Python Casting
Casting Code Challenge
Python Strings
Python Strings Slicing Strings Modify Strings Concatenate Strings Format Strings Escape Characters String Methods String Exercises Code Challenge
Python Booleans
Booleans Code Challenge
Python Operators
Python Operators Arithmetic Operators Assignment Operators Ternary Operator Comparison Operators Logical Operators Identity Operators Membership Operators Bitwise Operators Operator Precedence Code Challenge
Python Lists
Python Lists Access List Items Change List Items Add List Items Remove List Items Loop Lists List Comprehension Sort Lists Copy Lists Join Lists List Methods List Exercises Code Challenge
Python Tuples
Python Tuples Access Tuples Update Tuples Unpack Tuples Loop Tuples Join Tuples Tuple Methods Tuple Exercises Code Challenge
Python Sets
Python Sets Access Set Items Add Set Items Remove Set Items Loop Sets Join Sets Frozenset Set Methods Set Exercises Code Challenge
Python Dictionaries
Python Dictionaries Access Items Change Items Add Items Remove Items Loop Dictionaries Copy Dictionaries Nested Dictionaries Dictionary Methods Dictionary Exercises Code Challenge
Python If...Else
Python If Python Elif Python Else Shorthand If Logical Operators Nested If Pass Statement Code Challenge
Python Match
Match Code Challenge
Python While Loops
While Loops Code Challenge
Python For Loops
For Loops Code Challenge
Python Functions
Python Functions Python Arguments Python *args / **kwargs Python Scope Python Decorators Python Lambda Python Recursion Python Generators Code Challenge
Python Range
Range Code Challenge
Python Arrays
Arrays Code Challenge
Python Iterators
Iterators Code Challenge
Python Modules
Modules Code Challenge
Python Dates
Dates Code Challenge
Python Math
Math Code Challenge
Python JSON
JSON Code Challenge
Python RegEx
RegEx Code Challenge
Python PIP Python Try...Except
Try...Except Code Challenge
Python String Formatting
String Formatting Code Challenge
Python None
None Code Challenge
Python User Input Python VirtualEnv

Python Classes

Python OOP Python Classes/Objects
Classes/Objects Code Challenge
Python __init__ Method
__init__ Method Code Challenge
Python self Parameter
self Parameter Code Challenge
Python Class Properties
Class Properties Code Challenge
Python Class Methods
Class Methods Code Challenge
Python Inheritance
Inheritance Code Challenge
Python Polymorphism
Polymorphism Code Challenge
Python Encapsulation
Encapsulation Code Challenge
Python Inner Classes

File Handling

Python File Handling Python Read Files Python Write/Create Files Python Delete Files

Python Modules

NumPy Tutorial Pandas Tutorial SciPy Tutorial Django Tutorial

Python Matplotlib

Matplotlib Intro Matplotlib Get Started Matplotlib Pyplot Matplotlib Plotting Matplotlib Markers Matplotlib Line Matplotlib Labels Matplotlib Grid Matplotlib Subplot Matplotlib Scatter Matplotlib Bars Matplotlib Histograms Matplotlib Pie Charts

Machine Learning

Getting Started Mean Median Mode Standard Deviation Percentile Data Distribution Normal Data Distribution Scatter Plot Linear Regression Polynomial Regression Multiple Regression Scale Train/Test Decision Tree Confusion Matrix Hierarchical Clustering Logistic Regression Grid Search Categorical Data K-means Bootstrap Aggregation Cross Validation AUC - ROC Curve K-nearest neighbors

Python DSA

Python DSA Lists and Arrays Stacks Queues Linked Lists Hash Tables Trees Binary Trees Binary Search Trees AVL Trees Graphs Linear Search Binary Search Bubble Sort Selection Sort Insertion Sort Quick Sort Counting Sort Radix Sort Merge Sort

Python MySQL

MySQL Get Started MySQL Create Database MySQL Create Table MySQL Insert MySQL Select MySQL Where MySQL Order By MySQL Delete MySQL Drop Table MySQL Update MySQL Limit MySQL Join

Python MongoDB

MongoDB Get Started MongoDB Create DB MongoDB Collection MongoDB Insert MongoDB Find MongoDB Query MongoDB Sort MongoDB Delete MongoDB Drop Collection MongoDB Update MongoDB Limit

Python Cert

Python Certificate

Python Reference

Python Overview Python Built-in Functions Python String Methods Python List Methods Python Dictionary Methods Python Tuple Methods Python Set Methods Python File Methods Python Keywords Python Exceptions Python Glossary

Module Reference

Built-in Modules Random Module Requests Module Statistics Module Math Module cMath Module

Python How To

Remove List Duplicates Reverse a String Add Two Numbers

Python Examples

Python Examples Python Compiler Python Exercises Python Quiz Python Challenges Python Practice Problems Python Server Python Syllabus Python Study Plan Python Interview Q&A Python Bootcamp Python Training

Python Sets Code Challenge

❮ Previous Next ❯

Challenge: Sets Basics

Test your understanding of creating, adding, removing, and checking set items.

❮ Previous Next ❯
PLUS
SPACES
GET CERTIFIED
FOR TEACHERS
PRACTICE
CONTACT US
×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
sales@w3schools.com

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
help@w3schools.com

Top Tutorials
HTML Tutorial
CSS Tutorial
JavaScript Tutorial
How To Tutorial
SQL Tutorial
Python Tutorial
W3.CSS Tutorial
Bootstrap Tutorial
PHP Tutorial
Java Tutorial
C++ Tutorial
jQuery Tutorial
Top References
HTML Reference
CSS Reference
JavaScript Reference
SQL Reference
Python Reference
W3.CSS Reference
Bootstrap Reference
PHP Reference
HTML Colors
Java Reference
AngularJS Reference
jQuery Reference
Top Examples
HTML Examples
CSS Examples
JavaScript Examples
How To Examples
SQL Examples
Python Examples
W3.CSS Examples
Bootstrap Examples
PHP Examples
Java Examples
XML Examples
jQuery Examples
Get Certified
 HTML Certificate
CSS Certificate
JavaScript Certificate
Front End Certificate
SQL Certificate
Python Certificate
PHP Certificate
jQuery Certificate
Java Certificate
C++ Certificate
C# Certificate
XML Certificate
FORUM ABOUT ACADEMY
W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning.
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness
of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookies and privacy policy.

Copyright 1999-2026 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.

-->
ResultError
Your code has an error. Check the output below for details.
Click Check Code to see the result here.
Running