Check if a List is Empty in Python

To check if a list is empty in Python, you can use the if not list condition, the len() function, or compare it with an empty list []. Each approach ensures an efficient way to determine whether a list has elements or not.

Examples

1. Check if a List is Empty using if not list (Pythonic Way)

Python considers an empty list as False when used in a boolean context. This allows us to check if a list is empty using if not.

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# Creating an empty list
my_list = []

# Checking if the list is empty
if not my_list:
    print("The list is empty.")
else:
    print("The list is not empty.")

Explanation:

Here, my_list is initialized as an empty list. The statement if not my_list evaluates to True because the list contains no elements, triggering the first print() statement.

Output:

The list is empty.

2. Check if a List is Empty using len() Function

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

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# Creating an empty list
my_list = []

# Checking if the list is empty using len()
if len(my_list) == 0:
    print("The list is empty.")
else:
    print("The list is not empty.")

Explanation:

Here, len(my_list) calculates the number of elements in the list. Since len(my_list) is 0, the condition len(my_list) == 0 evaluates to True, and it prints “The list is empty.”

Output:

The list is empty.

3. Comparing with an Empty List []

We can compare the list directly with an empty list [] to check if it is empty.

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# Creating an empty list
my_list = []

# Checking if the list is empty by comparing with []
if my_list == []:
    print("The list is empty.")
else:
    print("The list is not empty.")

Explanation:

Here, we use the equality operator == to check if my_list is equal to an empty list []. Since both are empty, the condition evaluates to True and prints “The list is empty.”

Output:

The list is empty.

4. Check if a List is Empty using bool() Function

The bool() function converts a list into a boolean value, returning False if it is empty and True otherwise.

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# Creating an empty list
my_list = []

# Checking if the list is empty using bool()
if not bool(my_list):
    print("The list is empty.")
else:
    print("The list is not empty.")

Explanation:

The bool(my_list) function returns False for an empty list. Using if not bool(my_list), we check if the list is empty and print the appropriate message.

Output:

The list is empty.

Conclusion

Here are four effective ways to check if a list is empty in Python:

  1. if not list: The most Pythonic way, as empty lists evaluate to False.
  2. len(list) == 0: Explicitly checks the length of the list.
  3. list == []: Directly compares the list with an empty list.
  4. bool(list): Converts the list into a boolean value.

Using if not list is the recommended approach for readability and efficiency in Python.