How to Check if a List Is Empty in Python

Finding how to check if a list is empty in Python is not so a tricky task as you think. There are few effective methods available to make your functionalities easy. And of course, list play a paramount role in python that come up with few tempting characteristics listed in the below for your reference.

Mutability – It signifies dynamic that allows you to create and delete the entrie. This is add on benefit of python, which aids you whenever you need changes.

Iterability – The iterate concept is derived to going through all the elements in lists as well as in the mentioned order to make it suitable for loops. Therefore, make sure in advance about your list status.

By default, the empty list in python would return false as your output. However, some conditional statements are there to check if a list is empty in Python. In this following article, you are going to have some usual methods to identify the list is empty in Python.

How to check if a list is empty in Python?

In Python, the list data structure is one of the four most widely used data structures. Its flexibility, extensibility, and ease of use make it suitable for a wide range of applications. Python lists include a few unique features are iterability and mutability.

A list is a commonly used data structure. As a result, users frequently need to determine whether or not a list is empty. Some of the methods appear to be clearer, while others require less time to perform. Here are some methods to find whether the list is empty or not.

Using NOT Operator

In Python, an empty data structure is always evaluated as false, not operator will inverse the value of the argument or parameter. However, when the not operator is applied to false, then the result will be true, and the code inside the if condition is performed. It is one of the simplest ways to check if a list is empty or not. It is computationally quicker than any other method which is its main advantage.

If list is empty

empty_list = []
if not empty_list:
  print('The list is empty!')
else:
  print('The list contains something.')


Result:
The list is empty!

If list is not empty

empty_list = [3]
if not empty_list:
  print('The list is empty!')
else:
  print('The list contains something.')

Result:
The list contains something.

Using The len() Function

Take a look at a way that appears to be clearer, the built-in length function. If the list is empty, len() always returns 0. If you need to check if the list is empty using this len(), define it inside the if condition such as len()==0. And then, while the program runs it checks the condition whether it is true or false. When the list contains nothing in it, then the list is empty or null.

If list is empty

empty_list = []
if len(empty_list) == 0:
    print('The list is empty!')
else:	
    print('The list contains something.')

Result:
The list is empty!

If list is not empty

empty_list = []
if len(empty_list) >= 2:
    print('The list is empty!')
else:
    print('The list contains something.')

Result
The list contains something.

Comparing With An Empty List

The user compares their list with compare_with, which is an empty list. It is a quite straightforward technique to analyze whether the list is null or not. You just need to define a statement by using an empty list, for instance, compare_with = []. Then you could be able to check the statement by comparing them with each other. If the empty list matches with the compare_with the statement, then the output is zero that is the list is empty.

If list is empty

empty_list = []
compare_with = []
if empty_list == compare_with:
  print('The list is empty!')
else:	
  print('The list contains something.')

Result:
The list is empty!

If list is not empty

empty_list = []
compare_with = [3]
if empty_list == compare_with:
  print('The list is empty!')
else:
  print('The list contains something.')

Result:
The list contains something.

Using The Boolean Function

It is similar to the not operator, here we could check python list empty by using the bool() function. This function returns the Boolean value of the class or object as true or not. In the program, when the if condition is false, then proceeds to the else statement and it will print the output from the else statement.

If list is empty

empty_list = []
if bool (empty_list)==0:
  print('The list is empty!')
else:
  print('The list contains something.')

Result:
The list is empty!

If list is not empty

empty_list = []
if bool (empty_list)>=3:
  print('The list is empty!')
else:	
  print('The list contains something.')

Result:
The list contains something.

Using the PEP 8

The following pythonic way to do check the list is empty or not from the PEP 8 style guide. For this, you need to know about True Value Testing. The following are the majority of the built-in objects that are declared false:

  • Constants are always defined to be false: Null and False.
  • Any numeric type zero: 0, 0.0, 0j, Decimal(0), Fraction(0, 1)
  • Empty sequences & collections: ”, (), [], {}, set(), range(0)

Because an empty list is essentially a collection of nothing or null, it will be transformed to a False Boolean value. As a result, if py_list is empty, it is set to False. The second statement is similar to the first, except not would invert a false statement to a true statement. The if(len(list)) method is quite similar to this one. This is the favored method since it is the cleanest and quickest option available. You can also read more about this here.

If list is empty

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

Result:
List empty

If list is not empty

py_list= [3]
if py_list:
  print('List is not empty')
if not py_list:
  print('List empty')

Result
List is not empty

Conclusion

Hope so, you got the points that are listed in the above points. All the methods are very simple to write and execute! Probably, the best solution is revealed for your query of “how to Check if a List Is Empty in Python”.