Python List clear() Method

Python List clear() method removes all items from the List making it an empty/null list.

Example

Python3

lis = [1, 2, 3]
lis.clear()
print(lis)

Output

[]

What is List clear() Method?

list clear() is an in-built function in Python, that is used to delete every element from a list. It can make any list into a null list and should be used with caution.

It is one of the most basic and known list operations. It is very useful for re-using a list, as you can delete every element from that list.

List clear() Syntax

Syntax: list.clear()

Parameters

The clear() method doesn’t take any parameters

Returns

list clear() method doesn’t return a new list.

How to Use clear() Function in Python

The clear() function is very easy to use, just call it with a list you want to empty. Let’s understand how to clear a list with an example:

Python3

#creating a list
numbers = [1,2,3,4,5]
#using clear() function
numbers.clear()
#printing numbers list
print(numbers)

Output

[]

More Methods to clear a List

ln below examples we will empty a list using the clear function in Python:

1. Empty a List using clear() Method

In this example, we are creating a list, and we print it before clearing and after clearing in Python.

Python3

# Python program to clear a list
# using clear() method

# Creating list
GEEK = [6, 0, 4, 1]
print('GEEK before clear:', GEEK)

# Clearing list
GEEK.clear()
print('GEEK after clear:', GEEK)

Output

GEEK before clear: [6, 0, 4, 1]
GEEK after clear: []

2. Emptying the List Using del

In this example, we are creating a 2D list, and we are using the del keyword to delete the list data.

Python3

my_list = [1, 2, 3, 4, 5]
del my_list[:]
print(my_list)

Output

[]

3. Clearing 2D list using list clear() Method

In this example, we are creating a 2D list, and we are clearing the list at all indexes of the 2D list and printing it.

Python3

# Defining a 2-d list
lis = [[0, 0, 1],
       [0, 1, 0],
       [0, 1, 1]]

# clearing the list
lis.clear()

print(lis)

Output

[]

4. Clearing 2D list with specific index using list clear() Method

In this example, we are creating a 2D list, and we are clearing the list at the first index of the 2D list and printing it.

Python3

# Defining a 2-d list
lis = [[0, 0, 1],
       [0, 1, 0],
       [0, 1, 1]]

# clearing the list
lis[0].clear()

print(lis)

Output

[[], [0, 1, 0], [0, 1, 1]]

5. Using del Keyword vs list clear() Method

We can use the del keyword to delete the slice of a list from memory. But while using the list.clear() method, it modifies the list in place by removing all elements of the list. Nevertheless, the output from both approaches is the same.

Python3

lis_1 = [1, 3, 5]

lis_2 = [7, 9, 11]

# using clear method
lis_1.clear()
print("List after using clear():", lis_1)

# using del to clear items
del lis_2[:]
print("List after using del:", lis_2)

Output

List after using clear(): []
List after using del: []

Note: We are not directly using del lis_2, since it’ll delete the list object, but we want to delete the contents of the list, so we are deleting the slice of the list representing the complete list.

We have discussed the definition, syntax, and examples of the list clear() method in Python. We also looked at other methods used to clear a list. The list clear() function is a very useful function of list methods as it helps us to re-use a list.

Read Other Python List Methods