Remove all the occurrences of an element from a list in Python
The task is to perform the operation of removing all the occurrences of a given item/element present in a list. Examples :
Input : 1 1 2 3 4 5 1 2 1 Output : 2 3 4 5 2 Explanation : The input list is [1, 1, 2, 3, 4, 5, 1, 2] and the item to be removed is 1. After removing the item, the output list is [2, 3, 4, 5, 2] Input : 5 6 7 8 9 10 7 Output : 5 6 8 9 10
In this article, we shall see how to execute this task in 3 ways :
- Using list comprehension
- Using filter() and __ne__
- Using remove()
Method 1 : Using list comprehension The list comprehension can be used to perform this task in which we just check for a match and reconstruct the list without the target element. We can create a sublist of those elements in the list that satisfies a certain condition.
Python3
# Python 3 code to demonstrate# the removal of all occurrences of a# given item using list comprehensiondef remove_items(test_list, item): # using list comprehension to perform the task res = [i for i in test_list if i != item] return res# driver codeif __name__=="__main__": # initializing the list test_list = [1, 3, 4, 6, 5, 1] # the item which is to be removed item = 1 # printing the original list print ("The original list is : " + str(test_list)) # calling the function remove_items() res = remove_items(test_list, item) # printing result print ("The list after performing the remove operation is : " + str(res)) |
Output
The original list is : [1, 3, 4, 6, 5, 1] The list after performing the remove operation is : [3, 4, 6, 5]
Method 2 : Using filter() and __ne__ We filter those items of the list which are not equal __ne__ to the item.
Python3
# Python 3 code to demonstrate# the removal of all occurrences of# a given item using filter() and __ne__def remove_items(test_list, item): # using filter() + __ne__ to perform the task res = list(filter((item).__ne__, test_list)) return res# driver codeif __name__=="__main__": # initializing the list test_list = [1, 3, 4, 6, 5, 1] # the item which is to be removed item = 1 # printing the original list print ("The original list is : " + str(test_list)) # calling the function remove_items() res = remove_items(test_list, item) # printing result print ("The list after performing the remove operation is : " + str(res)) |
Output
The original list is : [1, 3, 4, 6, 5, 1] The list after performing the remove operation is : [3, 4, 6, 5]
Method 3 : Using remove() In this method, we iterate through each item in the list, and when we find a match for the item to be removed, we will call remove() function on the list.
Python3
# Python 3 code to demonstrate# the removal of all occurrences of# a given item using remove()def remove_items(test_list, item): # remove the item for all its occurrences c = test_list.count(item) for i in range(c): test_list.remove(item) return test_list# driver codeif __name__=="__main__": # initializing the list test_list = [1, 3, 4, 6, 5, 1] # the item which is to be removed item = 1 # printing the original list print ("The original list is :" + str(test_list)) # calling the function remove_items() res = remove_items(test_list, item) # printing result print ("The list after performing the remove operation is :" + str(res)) |
Output
The original list is : [1, 3, 4, 6, 5, 1] The list after performing the remove operation is : [3, 4, 6, 5]
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