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.

• Sets are written using curly braces {}.

• They automatically remove duplicate values.

• Since they are unordered, elements do not have a fixed position.

• Sets are useful for mathematical operations like union, intersection, and difference. 

📌This article will help you understand:

• What is a set

• How to create sets

• Set properties

• Set operations with examples

Note:Sets are commonly used when you need unique values and fast operations.

What is a Set in Python?

A set is a collection of unique (no duplicate) elements written inside curly brackets {}.

• Sets do not allow duplicate values.

• They are unordered, so elements do not have a fixed position.

• Sets are unindexed, so we cannot access elements using index numbers.

• They are useful for storing unique data and performing set operations.

Example:

numbers = {1, 2, 3, 4}   # Create a set with unique elements

print(numbers)              # Print the set

Output (order may vary):
{1, 2, 3, 4}

"Code executed successfully"  

Note:Even if you add duplicate values, sets will automatically remove duplicates.
Creating a Set :
A set is created using curly brackets {} with comma-separated values.
Sets store unique values only.
They can contain different data types.
Duplicate values are automatically removed.
Sets are unordered, so output order may change.
Syntax:
set_name = {value1, value2, value3}

Example 1: Simple Set:
fruits = {"Apple", "Banana", "Mango"}   # Create a set of fruits

print(fruits)                                               # Print the set
Output(order may vary):
{'Apple', 'Banana', 'Mango'}

"Code executed successfully"  
Example 2: Set with Different Data Types:
data = {10, "Python", 3.5, True}   # Set with multiple data types

print(data)                                      # Print the set
Output (order may vary):
{10, 'Python', 3.5, True}
"Code executed successfully"  

Note:Sets automatically remove duplicates and do not maintain order.
Duplicate Values Not Allowed:
Sets do not allow duplicate values; only unique elements are stored.
When duplicate values are added, Python automatically removes them.
This makes sets useful for storing unique data.
Duplicate removal happens automatically during creation.
Example:
nums = {1, 2, 2, 3, 4}   # Duplicate value 2 is added

print(nums)              # Print the set (duplicates removed)

Output:
{1, 2, 3, 4}
"Code executed successfully"  

Note:Sets ensure all elements are unique without extra code.
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