Python check empty list

This article will explore different ways to check if list is empty in python with example programs.

Method 1: Using len() function

Python len() function is used to find the length of a list or the number of elements in it.
For empty list, len() will return 0.
So, to check if list is empty or not, compare the return value with 0 as shown below.

l = []
if len(l) == 0:
   print('List is empty')

Comparison with 0 can be skipped when using len().
So, above code can be shortened to

l = [] 
if len(l): 
  print('List is empty')

PEP(Python Enhancement Proposal) 8 does not recommend this syntax.

Method 2: Checking empty sequence

PEP 8 states that empty sequences(strings, lists or tuples) are False. So, empty list is False and non-empty list is True.

Below syntax checks if a list is empty in python

l = [] 
if not l: 
  print('List is empty')

Applying not before empty list makes it True, so the if test passes.
This syntax is recommended by PEP 8.

To check for non-empty list, use below code

l = [1] 
if l: 
  print('List is not empty')

Method 3: Compare with empty list

Compare the list to be checked with an empty list using == operator.
If the list to check is empty, it will return True as shown below

list_to_check = []
empty_list = []
if list_to_check == empty_list:
   print('List is empty')

Conclusion

This article has shown different ways to check if a list is empty in Python.
Method 1 uses the len() function to count the number of items in the list.
Method 2 checks if the list is empty by treating it as a condition directly.
Method 3 simply compares the list to an empty list.
These methods give you options depending on what works best for you.
Mastering these techniques will help you handle empty lists in your Python code more easily.