How to Efficiently Create Two-Dimensional Lists in Python?

Creating Two-Dimensional Lists in Python

Establishing two-dimensional lists (also known as lists of lists) in Python can be a valuable tool. Let's explore a common approach and a potential improvement.

Traditional Approach:

One method for initializing a two-dimensional list involves creating a nested loop to populate each element with the same variable. Consider the following code:

def initialize_twodlist(foo):
    twod_list = []
    new = []
    for i in range(0, 10):
        for j in range(0, 10):
            new.append(foo)
        twod_list.append(new)
        new = []

This approach generates the desired result but can appear cumbersome.

Improved Method:

A more efficient and elegant way to create a two-dimensional list is through list comprehension:

t = [[0] * 3 for i in range(3)]

This code initializes a two-dimensional list with 3 rows and 3 columns, with each element set to 0.

Warning:

It's essential to avoid using [[v] n] n in such scenarios, as this can create a trap where modifying one element affects all others. Instead, use separate list comprehensions for each row to maintain independent lists.

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