Python – Random insertion of elements K times

When it is required to randomly insert elements K times, the random package provides methods like randint() and choice() to select random positions and elements for insertion.

Example

Below is a demonstration of the same −

import random

my_list = [34, 12, 21, 56, 8, 9, 0, 3, 41, 11, 90]

print("The list is : ")
print(my_list)

print("The list after sorting is : ")
my_list.sort()
print(my_list)

to_add_list = ["Python", "Object", "oriented", "language", "cool"]

K = 3
print("The value of K is")
print(K)

for element in range(K):
    index = random.randint(0, len(my_list))
    my_list = my_list[:index] + [random.choice(to_add_list)] + my_list[index:]

print("The resultant list is :")
print(my_list)

The output of the above code is −

The list is : 
[34, 12, 21, 56, 8, 9, 0, 3, 41, 11, 90]
The list after sorting is : 
[0, 3, 8, 9, 11, 12, 21, 34, 41, 56, 90]
The value of K is
3
The resultant list is :
[0, 3, 8, 9, 11, 12, 'Python', 21, 34, 41, 56, 90, 'Object', 'oriented']

How It Works

The algorithm performs the following steps −

• Import the random module to access random number generation functions.

• Define a list of integers and sort it using the sort() method for better visualization.

• Create a list of elements to be randomly inserted into the original list.

• Use random.randint(0, len(my_list)) to generate a random index position.

• Use random.choice(to_add_list) to select a random element from the insertion list.

• Insert the selected element at the random position using list slicing and concatenation.

• Repeat this process K times to insert K random elements.

Alternative Approach Using insert()

You can also use the insert() method for a more direct approach −

import random

numbers = [10, 20, 30, 40, 50]
elements_to_add = ["A", "B", "C", "D"]
K = 2

print("Original list:", numbers)

for i in range(K):
    random_index = random.randint(0, len(numbers))
    random_element = random.choice(elements_to_add)
    numbers.insert(random_index, random_element)

print("List after", K, "random insertions:", numbers)

Original list: [10, 20, 30, 40, 50]
List after 2 random insertions: [10, 'C', 20, 30, 'A', 40, 50]

Conclusion

Random insertion uses random.randint() to generate random positions and random.choice() to select random elements. The insert() method provides a cleaner approach than list slicing for single element insertions.