How to check if a list is empty in Python?

In Python, a list is an ordered sequence that can hold several object types, such as integers, characters, or floats. In this article, we will show you how to check if the given input list is empty or not using Python.

Below are the 5 methods to accomplish this task ?

• Using not operator

• Using len() function

• By Comparing with an Empty List

• Using __len__() Method

• Using NumPy Module

Using the NOT Operator

In Python, empty lists evaluate to False in boolean context. The not operator provides the most Pythonic way to check for empty lists ?

# Non-empty list
numbers = [1, 2, 3, 4, 5]

if not numbers:
    print('Empty list')
else:
    print('List is not empty:', numbers)

List is not empty: [1, 2, 3, 4, 5]

Let's test with an empty list ?

# Empty list
empty_list = []

if not empty_list:
    print('Empty list')
else:
    print('List is not empty:', empty_list)

Empty list

Using the len() Function

The len() function returns the number of elements in a list. An empty list has length 0 ?

# Empty list
items = []

if len(items) == 0:
    print('Empty list')
else:
    print('Not empty list')

Empty list

Comparing with an Empty List

You can directly compare a list with an empty list [] using the equality operator ?

# Empty list
data = []

if data == []:
    print('Empty list')
else:
    print('List is not empty:', data)

Empty list

Using __len__() Method

The __len__() method is the underlying implementation that len() calls. However, using len() directly is preferred ?

# Empty list
values = []

if values.__len__() == 0:
    print('Empty list')
else:
    print('Not empty list')

Empty list

Using NumPy Module

When working with NumPy arrays, you can check the size attribute to determine if the array is empty ?

import numpy as np

# Empty list
numbers = []

# Convert list to NumPy array
array = np.array(numbers)

if array.size == 0:
    print('Empty list')
else:
    print('List is not empty')

Empty list

Comparison

Conclusion

The not operator is the most Pythonic and efficient way to check for empty lists. Use len() when you need the actual count, and NumPy's size when working with arrays.