List expansion by K in Python

In this article, we are going to learn how to expand a list by replicating each element K times. We'll explore two different approaches to solve this problem efficiently.

Method 1: Using List Replication Operator

This method uses the multiplication operator to replicate elements and concatenates them to build the expanded list ?

# initializing the list
numbers = [1, 2, 3]
K = 5

# empty list
result = []

# expanding the list
for i in numbers:
    result += [i] * K

# printing the list
print(result)

The output of the above code is ?

[1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3]

Method 2: Using List Comprehension with Nested Loop

This method uses list comprehension with a nested loop structure to replicate each element K times ?

# initializing the list
numbers = [1, 2, 3]
K = 5

# expanding the list using list comprehension
result = [i for i in numbers for j in range(K)]

# printing the list
print(result)

The output of the above code is ?

[1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3]

How It Works

Method 1: Creates a new list [i] * K for each element and concatenates using += operator.

Method 2: The list comprehension [i for i in numbers for j in range(K)] iterates through each element in the original list and repeats it K times using the inner loop.

Comparison

Conclusion

Both methods effectively expand lists by replicating elements K times. Use list replication for better readability or list comprehension for improved performance and memory efficiency.