Find the length of a set in Python

Last Updated : 07 Jan, 2022

In Python, a Set is a collection data type that is unordered and mutable. A set cannot have duplicate elements. Here, the task is to find out the number of elements present in a set. See the below examples.

Examples:

Input: a = {1, 2, 3, 4, 5, 6}
Output: 6

Input: a = {'Geeks', 'For'}
Output: 2

The idea is use len() in Python

Find-Length-of-set

Example 1:

Python3

# Python program to find the length 
# of set 
  
set1 = set()   
    
# Adding element and tuple to the Set  
set1.add(8)  
set1.add(9)  
set1.add((6, 7))  
  
print("The length of set is:", len(set1)) 

Output:

The length of set is: 3

Example 2:

Python3

n = len({1, 2, 3, 4, 5}) 
  
print("The length of set is:", n) 

Output:

The length of set is: 5

How does len() work?
len() works in O(1) time as the set is an object and has a member to store its size. Below is description of len() from Python docs.

Return the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).