In this article, let’s discuss different ways to clear a list in Python. Python provides a lot of different ways to clear a list and we will discuss them in this article.
Example
Input: [2, 3, 5, 6, 7] Output: [] Explanation: Python list is cleared and it becomes empty so we have returned empty list.
Different Ways to Remove from a List in Python
There are many ways of clearing the list through methods of different constructs offered by Python language. Let’s try to understand each of the methods one by one.
- Using clear()
- Reinitializing the list
- Using “*= 0”
- Using del
- Using pop() method
- Using slicing
Clear a List using Python List clear()
In this example, we are using clear() method to clear a list in Python.
Python3
GEEK = [6, 0, 4, 1]print('GEEK before clear:', GEEK)# Clearing listGEEK.clear()print('GEEK after clear:', GEEK) |
GEEK before clear: [6, 0, 4, 1] GEEK after clear: []
Clear a List by Reinitializing the List
The initialization of the list in that scope initializes the list with no value. i.e list of size 0. Let’s see the example demonstrating Method 1 and 2 to clear list.
Python3
list1 = [1, 2, 3]# Printing list2 before deletingprint("List1 before deleting is : " + str(list1))# deleting list using reinitializationlist1 = []# Printing list2 after reinitializationprint("List1 after clearing using reinitialization : " + str(list1)) |
List1 before deleting is : [1, 2, 3] List1 after clearing using reinitialization : []
Clearing a Python List Using “*= 0”
This is a lesser-known method, but this method removes all elements of the list and makes it empty. In this example, we are using *=0 to clear a list.
Python3
# Initializing listslist1 = [1, 2, 3]# Printing list2 before deletingprint("List1 before clearing is : " + str(list1))list1*=0# Printing list2 after reinitializationprint("List1 after clearing using *=0 : " + str(list1)) |
List1 before clearing is : [1, 2, 3] List1 after clearing using *=0 : []
Clearing a List Using del
Python del can be used to clear the list elements in a range, if we don’t give a range, all the elements are deleted. In this example, we are using del keyword to clear a list.
Python3
list1 = [1, 2, 3]list2 = [5, 6, 7]# Printing list1 before deletingprint("List1 before deleting is : " + str(list1))# deleting list1 using deldel list1[:]print("List1 after clearing using del : " + str(list1))# Printing list2 before deletingprint("List2 before deleting is : " + str(list2))# deleting list using deldel list2[:]print("List2 after clearing using del : " + str(list2)) |
List1 before deleting is : [1, 2, 3] List1 after clearing using del : [] List2 before deleting is : [5, 6, 7] List2 after clearing using del : []
Python pop() method To Clear a List
In this example, we are using pop() method to clear a list.
Python3
list1 = [1, 2, 3]# Printing list1 before deletingprint("List1 before deleting is : " + str(list1))# deleting list1while(len(list1) != 0): list1.pop()print("List1 after clearing using del : " + str(list1)) |
List1 before deleting is : [1, 2, 3] List1 after clearing using del : []
Time Complexity: O(n^2) where n is the length of the list list1.
Auxiliary Space: O(1).
Clear a List using Slicing
This method involves using slicing to create a new list with no elements, and then assigning it to the original list variable. In this example, we are using slicing to clear a list.
Python3
# Initializing listlst = [1, 2, 3, 4, 5]print("List before clearing: ",lst)# Clearing list using slicinglst = lst[:0]print("List after clearing using Slicing: ",lst) |
List before clearing: [1, 2, 3, 4, 5] List after clearing using Slicing: []
Time Complexity: O(1)
Auxiliary Space: O(n), where n is length of list.
