Data Structures in Python - Episode 4: Sets and Frozensets

Data Structures in Python - Episode 4: Sets and Frozensets

Introduction

Sets are unordered collections of unique elements in Python. They are extremely useful when you need to eliminate duplicates or perform set operations like union, intersection, and difference.

Example 1: Creating a Set

# Creating a set
my_set = {1, 2, 3, 4, 5}
print(my_set)

{1, 2, 3, 4, 5}

Example 2: Set Operations

# Set operations
set_a = {1, 2, 3}
set_b = {3, 4, 5}

print("Union:", set_a | set_b)
print("Intersection:", set_a & set_b)
print("Difference:", set_a - set_b)

Union: {1, 2, 3, 4, 5}
Intersection: {3}
Difference: {1, 2}

What is a Frozenset?

A frozenset is just like a set, but it is immutable — meaning you cannot change its elements after creation.

# Creating a frozenset
frozen = frozenset([1, 2, 3, 4])
print(frozen)

frozenset({1, 2, 3, 4})

Quick Recap

Data Structure	Changeable?	Ordered?	Allows Duplicates?
Set	Yes	No	No
Frozenset	No	No	No

Important Notes

Tip: Sets automatically remove duplicate values!
Warning: Sets cannot contain mutable types like lists.