Python List remove() Method
Last Updated :
21 Dec, 2023
Python list remove() method removes a given element from the list.
Example:
Python3
lis = ['a', 'b', 'c']
lis.remove("b")
print(lis)
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List remove() Syntax
list_name.remove(obj)
Parameter
- obj: object to be removed from the list
Returns
The method does not return any value but removes the given object from the list.
Exception
If the element doesn’t exist, it throws ValueError: list.remove(x): x not in list exception.
Note: It removes the first occurrence of the object from the list.
What is Python list remove() Function
The list remove() function in Python removes the first occurrence of a given item from the list. It make changes to the current list.
It only takes one argument that is the element you want to remove and if that element is not present in the list, it gives ValueError.
It is very useful in removing incorrect values from a list, without affecting the rest of the list.
How to Use List remove() Method
remove() function is a very important function of lists. It is very easy to use, just call the function with a list object and pass the value you want to remove as a parameter. Let’s look at an example to understand how to remove an element from a list:
More Examples of list remove()
Let’s see some of the most common use-case scenarios with the list remove() function to have a deep understanding of the topic.
- Remove an element from the list
- Deleting Element that doesn’t Exist
- Remove Duplicates from List in Python
- Remove all Occurrences of a value from a List
- Removing a nested list element from a list
- Removing elements from a list based on a condition
- Removing an Element by Value from a List
- Removing elements from a list using the Filter function
1. Remove an element from the list in Python
In this example, we are showing how we can use the remove() function with the Python list. Remove function removes the specified element’s first occurrence in the list.
Python3
list1 = [ 1, 2, 1, 1, 4, 5 ]
list1.remove(1)
print(list1)
list2 = [ 'a', 'b', 'c', 'd' ]
list2.remove('a')
print(list2)
|
Output
[2, 1, 1, 4, 5]
['b', 'c', 'd']
Time complexity: for the first list removal: O(n)
Time complexity: for the second list removal: O(1)
Space complexity: O(1) for both cases.
2. Deleting Element that doesn’t Exist
In this example, we are removing the element ‘e’ which does not exist.
Python3
list2 = [ 'a', 'b', 'c', 'd' ]
list2.remove('e')
print(list2)
|
Output
Traceback (most recent call last):
File "/home/e35b642d8d5c06d24e9b31c7e7b9a7fa.py", line 8, in
list2.remove('e')
ValueError: list.remove(x): x not in list
3. Remove Duplicates from the List in Python
In this example, we are removing the element which comes multiple times in the list.
Python3
list2 = [ 'a', 'b', 'c', 'd', 'd', 'e', 'd' ]
list2.remove('d')
print(list2)
|
Output
['a', 'b', 'c', 'd', 'e', 'd']
Time complexity: O(n)
Space complexity: O(1)
Note: If a list contains duplicate elements, it removes the first occurrence of the object from the list.
4. Remove all Occurrences of a value from a List
Let’s see how to remove all the occurrences of a value from a list.
Example 1: Remove all the 1’s from the list and print the list.
In this example, we remove 1 from the list until all 1 is removed.
Python3
list1 = [1, 2, 3, 4, 1, 1, 1, 4, 5]
while (list1.count(1)):
list1.remove(1)
print(list1)
|
Time complexity: O(n^2)
Space complexity: O(1)
Example 2: Given a list, remove all the 2’s from the list using in keyword
In this example, we remove 2 from the list until all the 2 are removed.
Python3
mylist = [1, 2, 3, 2, 2]
while 2 in mylist:
mylist.remove(2)
print(mylist)
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Time complexity: O(n^2)
Space complexity: O(1) – The space complexity is O(1) since we are only modifying the existing list and not creating any additional data structures proportional to the input size.
5. Removing a nested list element from a list
In this example, we are removing a list from a 2d List.
Python3
data = [[1, 2], [3, 4], [5, 6]]
data.remove([3, 4])
print(data)
|
Time complexity: O(n)
Space complexity: O(1)
6. Removing elements from a list based on a condition using a list comprehension
In this example, we are moving numbers from the list using list comprehension.
Python3
numbers = [1, 2, 3, 4, 5]
numbers = [x for x in numbers if x != 3]
print(numbers)
|
Time complexity: O(n)
Space complexity: O(1)
7. Removing an Element by Value from a List
This example demonstrates how to remove a specific element (in this case, ‘3’) from a list using the remove() method. It first checks if the element exists in the list before attempting to remove it.
Python3
my_list = [1, 2, 3, 4, 5]
if 3 in my_list:
my_list.remove(3)
print("Updated list:", my_list)
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Output
Updated list: [1, 2, 4, 5]
Time complexity: O(n)
Space complexity: O(1)
8. Removing elements from a list using the Filter function
In this example, we are using the lambda function to check the condition and filter out the data from the list.
Python3
numbers = [1, 2, 3, 4, 5]
numbers = list(filter(lambda x: x != 3, numbers))
print(numbers)
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Time complexity: O(n)
Space complexity: O(n)
We have discussed the definition, uses and examples of the list remove() method in Python. The list remove function is an important list operating function and is used to remove a particular value from the list.
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