Check If a Python Set is Empty

In Python, sets are versatile data structures used to store unique elements. It’s common to need to check whether a set is empty in various programming scenarios. This article explores different methods to determine if a Python set is empty, providing developers with flexible approaches to suit their specific requirements.

Check if Set is Empty in Python

Below are some of the ways by which we can check if the set is empty in Python or not:

• Using the len()
• Using the == operator
• Using the bool()
• Using the != operator
• Using the not

Check if Set is Empty Using the len() Method

In this example, an attempt to create an empty set using curly braces results in the creation of an empty dictionary (`set`), not a set. The check using `len(set)` incorrectly evaluates to zero, leading to the incorrect output “The set is Empty.”

Python3

set = {}
if len(set) == 0:
    print("The set is Empty")
else:
    print("The set is not Empty")

Output

The set is Empty

Check if Set is Empty Using the == operator

In this example, an attempt is made to create an empty set using curly braces, but due to the capitalization of “Set,” it results in an empty dictionary (`Set`). The comparison `Set == {}` correctly identifies the empty set, leading to the output “The set is Empty.”

Python3

Set = {}
if Set == {}:
    print("The set is Empty")
else:
    print("The set is not Empty")

Output

The set is Empty

Check if Set is Empty Using the bool()

In this example, a dictionary is mistakenly assigned to the variable named “set.” The condition `bool(set)` evaluates to `False` since an empty dictionary is considered falsy, resulting in the output “The set is Empty.”

Python3

set = {}
if bool(set):
    print("The set is not Empty")
else:
    print("The set is Empty")

Output

The set is Empty

Check if Set is Empty Using the != operator

In this example, a dictionary is mistakenly assigned to the variable named “set.” The condition `set != {}` checks for non-equality with an empty dictionary, and since “set” is indeed an empty dictionary, the output will incorrectly be “The set is not Empty.”

Python3

set = {}

if set != {}:
    print("The set is not Empty")
else:
    print("The set is Empty")

Output

The set is Empty

Check if Set is Empty Using the not Keyword

In this example, an empty set is correctly created using the `set()` constructor, and the condition `not set` checks for its emptiness. The output will correctly be “The set is Empty.”

Python3

set = set()
if not set:
    print("The set is Empty")
else:
    print("The set is not Empty")

Output

The set is Empty