Python Sets: Definition, Properties, and Examples

 

✍️Introduction

In Python, a set is used to store multiple values in a single variable, just like lists and tuples.
But sets are unordered, unindexed, and do not allow duplicate values.

This article will help you understand:

• What is a set

• How to create sets

• Set properties

• Set operations with examples

What is a Set in Python?

A set is a collection of unique elements written inside curly brackets { }.

Example:

numbers = {1, 2, 3, 4}


Creating a Set
fruits = {"Apple", "Banana", "Mango"}

Set with different data types:
data = {10, "Python", 3.5, True}


Duplicate Values Not Allowed
Sets automatically remove duplicates.
nums = {1, 2, 2, 3, 4}
print(nums)
Output:
{1, 2, 3, 4}


Unordered and Unindexed
No index numbers
Order may change
❌ Invalid:
print(fruits[0])

Creating an Empty Set
❌ Wrong:
myset = {}

✅ Correct:
myset = set()


Set Length
print(len(fruits))

Adding Elements to a Set
fruits.add("Orange")

Add multiple items:
fruits.update(["Grapes", "Pineapple"])

Removing Elements from a Set
fruits.remove("Banana")   # Error if not found
fruits.discard("Apple")   # No error
fruits.pop()              # Removes random element

Looping Through a Set
for fruit in fruits:
    print(fruit)
Set Methods (Common)
Method              
Description
add()
Add element
update()
Add multiple
remove()
Remove element
discard()           
Remove without error
pop()
Remove random
clear()
Remove all
copy()
Copy set
Set Operations
Union
A = {1, 2, 3}
B = {3, 4, 5}
print(A | B)

Intersection
print(A & B)

Difference
print(A - B)

Symmetric Difference
print(A ^ B)

Checking Membership
print("Apple" in fruits)


Convert Set to List
mylist = list(fruits)


Difference Between List, Tuple, and Set
Feature         
List      
Tuple     
Set
Ordered
Yes
Yes
No
Changeable
Yes
No
Yes
Duplicates
Yes
Yes
No
Indexing
Yes
Yes
No


When to Use Sets?
Remove duplicate values
Perform mathematical operations
Fast membership checking
Real-Life Example
emails = {"a@gmail.com", "b@gmail.com", "a@gmail.com"}
print(emails)


❌ Common Mistakes
Using {} for empty set
Expecting order in output
Using index values
Conclusion
Sets are powerful and efficient data structures in Python.

They are best when you need unique data and fast operations.

💬 Quick Question

What will be the output?
s = {1, 2, 2, 3}
print(len(s))
Comment your answer 👇😊

📌 Related Articles:
Python Lists
Python Tuples
Python string