How to check if a list is empty

Posted in Python by Dirk - last update: Feb 15, 2024

Using the if-not statement

The most common way to check if a list is empty in Python is to use an if not statement. If a list is empty the condition evaluates to True; otherwise, it evaluates to False.

Example:

my_list = []

if not my_list:
    print("The list is empty")
else:
    print("The list is not empty")

In this example, if my_list is empty, the condition if not my_list will be True, and the program will print “The list is empty.” If my_list has elements, the condition will be False, and it will print “The list is not empty.”

This method also works if the list is None

Note: if the list doesn’t exist (i.e., it is not defined), trying to access or check its content directly will result in a NameError in Python. To deal with this situation, it’s a good practice to check whether the list exists before attempting to perform any operations on it.

This can be done with a try/except block

try:
    if not mylist:
        print("The list is empty")
    else:
        print("The list is not empty")
except NameError:
        print ("The list does not exist")

Alternative methods:

Using len() function

The len() function returns the number of elements in a list. If the length of the list is 0, it means the list is empty. e

Example:

my_list = []
if len(my_list) == 0:
    print("The list is empty")
else:
    print("The list is not empty")

This method does not work is the list can be None - if the list is Noneit will raise a TypeError: object of type 'NoneType' has no len()

This can be handled by adding an additional check for None in the if clause (if my_list is None or len(my_list) == 0 ) or wrapping the if statement in a try-except

try:
    # Assuming my_list is defined elsewhere in your code
    if my_list is None or len(my_list) == 0:
        print("The list is either None or empty")
    else:
        print("The list is not None and not empty")

except NameError:
    print("The list does not exist")

Comparison to an empty list

You can directly compare the list to an empty list.

my_list = []
if my_list == []:
    print("The list is empty")
else:
    print("The list is not empty")

This will not work if the list is None - if None the comparison is false - so you will get the ‘The list is not empty’ message.

While technically true, this might not be the result that you need or expect. Add an addtional check to the if clause - if my_list == [] or my_list is None

Using bool()

You can use the bool() function to convert the list to a boolean value, bool(mylist) will be False if the list is empty

my_list = []
if bool(my_list):
    print("The list is not empty")
else:
    print("The list is empty")

Using any()

The any() function returns True if at least one element in the iterable is true. In the case of an empty list, it returns False.


my_list = []
if not any(my_list):
    print("The list is empty")
else:
    print("The list is not empty")

This will not work if the list is None, it will generate a TypeError: 'NoneType' object is not iterable

Use an additional check in the if or wrap it in a try-except clause (see example above)