Python Sets

Satellite · Data Types

Python Sets

Sets track unique elements and support fast membership checks. Use them for deduplication, tagging, and math-like operations.

Use set operationsConsider frozenset

Creation

items = {1, 2, 3}
empty = set()
deduped = set(["a", "b", "a"])

Operations

a = {1, 2, 3}
b = {3, 4, 5}
a | b  # union
a & b  # intersection
a - b  # difference
a ^ b  # symmetric difference

Membership checks are O(1) on average: if email in unsubscribed: ...

Frozenset

Immutable set; use when you need to store sets inside other sets or as dict keys.

Next up in your learning path

Combine with dictionaries

Manage membership and counts together.

Companion

Use comprehensions

Build sets from loops quickly.

Reference

Compare tuples vs sets

Understand when immutability helps.

Companion