Different ways to Clear a List in Python

Given a list, the task is to remove all elements from it. For Example:

Input: [10, 20, 30, 40]
Output: []

Let's explore diiferent methods to clear a list in Python.

Using clear() Method

clear() empties the list directly by removing all elements from the same list object.

a = [1, 2, 3, 4, 5]
a.clear()
print(a)

[]

Explanation:

• clear() removes all elements from the list a in place.
• The list object remains the same, only its contents are erased.

Using del a[:]

del a[:] deletes every element inside the list using slicing while keeping the same list reference.

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

[]

Explanation:

• a[:] selects the entire list.
• del a[:] deletes all selected elements, leaving the list empty.

Using a Loop with pop()

This method removes elements one by one until the list becomes empty using pop(). It works but is the slowest option.

a = [1, 2, 3, 4, 5]
while a:
    a.pop()
print(a)

[]

Explanation:

• a.pop() removes the last element in each iteration.
• Loop continues until the list becomes empty.

Reassigning to []

Assigning the name to a new empty list does not modify the old list, it simply makes the variable point to a fresh empty list.

a = [1, 2, 3, 4, 5]
a = []
print(a)

[]

Explanation:

• a = [] assigns a new empty list to the variable a.
• The old list still exists if referenced elsewhere.

Note: Using a = [] does not clear the original list - it only reassigns the variable to a new empty list. If other variables reference the same list, they will still hold the old data.

Related Articles:

• clear() Method
• remove() Method