Python list remove()

Python List remove() is an inbuilt function in the Python programming language that removes a given object from the List. 

Syntax: 

list_name.remove(obj) 

Parameters:

• 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. 

Example 1: Remove element from the list  

Python3

# Python3 program to demonstrate the use of
# remove() method

# the first occurrence of 1 is removed from the list
list1 = [ 1, 2, 1, 1, 4, 5 ]
list1.remove(1)
print(list1)

# removes 'a' from list2
list2 = [ 'a', 'b', 'c', 'd' ]
list2.remove('a')
print(list2)

Output

[2, 1, 1, 4, 5]
['b', 'c', 'd']

Example 2: Deleting element that doesn’t exist

Python3

# Python3 program for the error in
# remove() method


# removes 'e' from list2
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

Example 3: Using remove() Method On a List having Duplicate Elements

Python3

# My List
list2 = [ 'a', 'b', 'c', 'd', 'd', 'e', 'd' ]

# removing 'd'
list2.remove('d')

print(list2)

Output

['a', 'b', 'c', 'd', 'e', 'd']

Note: If a list contains duplicate elements, it removes the first occurrence of the object from the list. 

Example 4: Given a list, remove all the 1’s from the list and print the list

Python3

# Python3 program for practical application
# of removing 1 until all 1 are removed from the list

list1 = [1, 2, 3, 4, 1, 1, 1, 4, 5]

# looping till all 1's are removed
while (list1.count(1)):
    list1.remove(1)

print(list1)

Output

[2, 3, 4, 4, 5]

Example 5: Given a list, remove all the 2’s from the list using in keyword 

Python3

# Python3 program for practical application
# of removing 2 until all 2 are removed from the list

mylist = [1, 2, 3, 2, 2]

# looping till all 2's are removed
while 2 in mylist:
    mylist.remove(2)

print(mylist)

Output

[1, 3]

Complexity Class:  

• Average case : O(N)
• Amortised Worst case : O(N)