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Oct 28, 2023 2 mins

Extend a Python List to a Desired Length

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Python is a powerful programming language, offers multiple ways to manipulate lists efficiently. One common scenario is extending a list with random values derived from its existing elements to a desired length. In this article, we explore three distinct approaches to achieve this goal and provide code examples along with the output.

Utilizing random.choice() and a Loop

The first approach involves using the random.choice() function along with a loop to iteratively extend the list with random values from its existing elements. The random.choice() function selects a random element from the given list, and this process is repeated for the desired number of times. Let’s dive into the code:

import random

original_list = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

for _ in range(10):
    original_list.append(random.choice(original_list))

print(original_list) # [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 90, 40, 10, 100, 80, 70, 30, 80, 50, 30, 10]

This method extends the list in-place and allows for the possibility of duplicate values in the resulting list.

Using List Comprehension

The second approach leverages list comprehension to create a new list containing both the original elements and randomly chosen elements from the original list. This approach is concise and easy to understand. Here’s the code:

import random

original_list = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

extended_list = original_list + [random.choice(original_list) for _ in range(10)]

print(extended_list) # # [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 90, 40, 10, 100, 80, 70, 30, 80, 50, 30, 10]

This approach creates a new list and appends the original elements along with randomly chosen ones, potentially resulting in duplicate values.

Utilizing random.sample() to Avoid Duplicates

The third approach focuses on avoiding duplicate values in the extended list. It employs the random.sample() function, which returns a new list containing unique elements randomly chosen from the original list. Let’s explore the code:

import random

original_list = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

extended_list = original_list + random.sample(original_list, 10)

print(extended_list) # # [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 90, 40, 10, 100, 80, 70, 30, 80, 50, 30, 10]

By using random.sample(), this approach ensures that the extended list contains unique values, providing a distinct advantage when duplicates are to be avoided.

Conclusion

In this article, we explored three distinct approaches to extend a Python list with random values derived from its existing elements. Each approach has its merits, and the choice depends on the specific requirements of your application. Approach 1 utilizes a loop and random.choice() for simplicity, Approach 2 employs list comprehension for conciseness, and Approach 3 employs random.sample() to avoid duplicates.

Understanding these techniques enhances your ability to manipulate lists effectively in Python, providing valuable tools for data manipulation, simulation, and diverse programming tasks. The flexibility of Python, coupled with these strategies, empowers developers to tackle a wide range of challenges when working with lists.


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