Python set intersection()

The intersection() method of Python sets is used to obtain the intersection of two or more sets.

Syntax

The syntax of intersection() method is as follows:

set1.intersection(set2, set3, ..., setn)

Here, set1, set2, set3 ... are the sets to be intersected.

Return Value

The intersection() method returns a new set containing the common elements of all the sets that are being intersected. If there are no common elements, an empty set is returned.

Example

# creating sets
set1 = {1, 2, 3, 4, 5}
set2 = {3, 4, 5, 6, 7}
set3 = {5, 6, 7, 8, 9}

# intersection of sets
set4 = set1.intersection(set2)
set5 = set1.intersection(set2, set3)

print("Intersection of set1 and set2:", set4)
print("Intersection of set1, set2 and set3:", set5)

Output:

Intersection of set1 and set2: {3, 4, 5}
Intersection of set1, set2 and set3: {5}

In the above example, the intersection() method is used to find the common elements between sets set1 and set2, as well as between sets set1, set2, and set3. The resulting sets are set4 and set5, respectively.

Performance

The intersection() method has a time complexity of O(min(n*m)) where n and m are the number of elements in the input sets. In the worst-case scenario, when all sets have the same number of elements, the time complexity becomes O(n^2). The space complexity of the method is O(min(n,m)).

Conclusion

The intersection() method is a useful tool for obtaining the common elements between two or more sets in Python. Its simplicity and efficiency make the method a popular choice for set operations in Python.