How to Find Intersection of Two Sets in Python

To find the intersection of two sets in Python, use the intersection() method or the & operator. Both return a new set containing elements common to both sets.

Syntax

You can find the intersection of two sets using either the intersection() method or the & operator.

• set1.intersection(set2): Returns a new set with elements common to both set1 and set2.
• set1 & set2: Another way to get the intersection using the & operator.

python

set1.intersection(set2)

# or

set1 & set2

Example

This example shows how to find the intersection of two sets using both the intersection() method and the & operator.

python

set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}

# Using intersection() method
common_elements_method = set1.intersection(set2)

# Using & operator
common_elements_operator = set1 & set2

print("Intersection using method:", common_elements_method)
print("Intersection using operator:", common_elements_operator)

Output

Intersection using method: {3, 4}
Intersection using operator: {3, 4}

Common Pitfalls

One common mistake is trying to use the intersection() method without parentheses, which will return a method object instead of the intersection set. Another is confusing intersection with union, which combines all elements instead of common ones.

python

set1 = {1, 2, 3}
set2 = {2, 3, 4}

# Wrong: missing parentheses
wrong = set1.intersection
print(wrong)  # This prints a method object, not the intersection

# Right:
right = set1.intersection(set2)
print(right)  # Correct intersection output

Output

<built-in method intersection of set object at 0x7f...>
{2, 3}

Quick Reference

Operation	Syntax	Description
Intersection (method)	set1.intersection(set2)	Returns a new set with elements common to both sets
Intersection (operator)	set1 & set2	Returns a new set with elements common to both sets
Union	set1.union(set2) or set1 | set2	Returns a new set with all elements from both sets
Difference	set1.difference(set2) or set1 - set2	Returns elements in set1 not in set2

Key Takeaways

Use intersection() method or & operator to find common elements between two sets.

Always include parentheses when calling intersection() to get the result set.

Intersection returns only elements present in both sets, not all elements combined.

Sets are unordered collections, so the order of elements in the result is not guaranteed.

Use union and difference methods for other set operations.