Python | Remove random element from list

Sometimes, while working with Python lists, we can have a problem or part of it, in which we desire to convert a list after deletion of some random element. This can have it’s application in gaming domain or personal projects. Let’s discuss certain way in which this task can be done. 

Method : Using randrange() + pop() In this, we just combine the functionality of above functions into one and achieve this task. The random element is chosen by randrange() and then is accessed and removed from the list using pop() 

Python3

# Python3 code to demonstrate working of
# Remove random element from list
# Using randrange() + pop()
import random

# initializing list
test_list = [6, 4, 8, 9, 10]

# printing list
print("The original list : " + str(test_list))

# Remove random element from list
# Using randrange() + pop()
test_list.pop(random.randrange(len(test_list)))

# Printing result
print("List after removal of random number : " + str(test_list))

Output

The original list : [6, 4, 8, 9, 10]
List after removal of random number : [6, 4, 8, 9]

Time Complexity: O(n), where n is the length of the list test_list 
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the res list 

Another approach to remove a random element from a list in Python is using the random.choice() method. This method returns a random element from a given list. After getting the random element, it can be removed from the list using the list.remove() method.

Python3

import random

test_list = [6, 4, 8, 9, 10]
print("The original list : " + str(test_list))

# remove a random element from list
random_element = random.choice(test_list)
test_list.remove(random_element)

# Printing result
print("List after removal of random number : " + str(test_list))
#This code is contributed by Edula Vinay Kumar Reddy

Output

The original list : [6, 4, 8, 9, 10]
List after removal of random number : [4, 8, 9, 10]

Time complexity: O(n)
Auxiliary Space: O(1)

Method : Using filter () and lambda(): 

Python3

# import the random library
import random
# Initialize the list
test_list = [6, 4, 8, 9, 10]
# Print the original list
print("The original list : " + str(test_list))
# Use the random.choice() function to randomly select an element from the list
random_element = random.choice(test_list)
# Use the filter function and a lambda function to remove the selected element from the list
test_list = list(filter(lambda x: x != random_element, test_list))
# Print the list after removal of the random element
print("List after removal of random number : " + str(test_list))
#This code is contributed by pinjala Jyothi

Output

The original list : [6, 4, 8, 9, 10]
List after removal of random number : [4, 8, 9, 10]

Time complexity: O(n)
Auxiliary Space: O(n-1) 

Method : Using del keyword

Python3

import random
test_list = [6, 4, 8, 9, 10]
random_element = random.choice(test_list)
# Print the original list
print("The original list : " + str(test_list))
del test_list[test_list.index(random_element)]
print("List after removal of random number :", test_list)
#This code is Contributed by Vinay Pinjala.

Output

The original list : [6, 4, 8, 9, 10]
List after removal of random number : [6, 4, 8, 9]

Time complexity: O(n)
Auxiliary Space: O(1)