Intersection() function Python

Python set intersection() method returns a new set with an element that is common to all set

The intersection of two given sets is the largest set, which contains all the elements that are common to both sets. The intersection of two given sets A and B is a set which consists of all the elements which are common to both A and B.

Python Set intersection() Method Syntax:

Syntax: set1.intersection(set2, set3, set4....) 
Parameters:

• any number of sets can  be passed

Return: Returns a set which has the intersection of all sets(set1, set2, set3...) with set1. It returns a copy of set1 only if no parameter is passed. 

Python Set intersection() Method Example:

s1 = {1, 2, 3}
s2 = {2, 3}
print(s1.intersection(s2))

Output:

{2, 3}

Example 1: Working of set intersection()

# Python3 program for intersection() function
set1 = {2, 4, 5, 6}
set2 = {4, 6, 7, 8}
set3 = {4, 6, 8}

# intersection of two sets
print("set1 intersection set2 : ",
      set1.intersection(set2))

# intersection of three sets
print("set1 intersection set2 intersection set3 :",
      set1.intersection(set2, set3))

Output: 

set1 intersection set2 :  {4, 6}
set1 intersection set2 intersection set3 : {4, 6}

Example 2: Python set intersection operator(&)

We can also get intersections using '&' operator.

# Python3 program for intersection() function
set1 = {2, 4, 5, 6}
set2 = {4, 6, 7, 8}
set3 = {1, 0, 12}

print(set1 & set2)
print(set1 & set3)

print(set1 & set2 & set3)

Output:

{4, 6}
set()
set()

Example 3: Python set intersection opposite

symmetric_difference() is an opposite to the Python Set intersection() method.

# Python3 program for intersection() function
set1 = {2, 4, 5, 6}
set2 = {4, 6, 7, 8}
set3 = {1, 0, 12}

print(set1.symmetric_difference(set2))
print(set1.symmetric_difference(set3))
print(set2.symmetric_difference(set3))

Output:

{2, 5, 7, 8}
{0, 1, 2, 4, 5, 6, 12}
{0, 1, 4, 6, 7, 8, 12}

Example 4: Python set intersection empty

Intersection of empty sets returns an empty set.

set1 = {}
set2 = {}

# union of two sets
print("set1 intersection set2 : ",
      set(set1).intersection(set(set2)))

Output:

set1 intersection set2 :  set()