How can you define an empty 2D array in Python?

In Python, you can define an empty 2D array using nested lists.

Here are several ways to define an empty two-dimensional array:

1. Use list comprehension:

rows = 3
cols = 4
array = [[None for _ in range(cols)] for _ in range(rows)]

1. Use nested loops:

rows = 3
cols = 4
array = []
for _ in range(rows):
    row = []
    for _ in range(cols):
        row.append(None)
    array.append(row)

1. Create an empty 2D array using the numpy library.

import numpy as np

rows = 3
cols = 4
array = np.empty((rows, cols))

1. Create an empty two-dimensional DataFrame using the pandas library.

import pandas as pd

rows = 3
cols = 4
array = pd.DataFrame(index=range(rows), columns=range(cols))

All of the methods above can be used to create an empty two-dimensional array of a specified size; you can choose the appropriate method based on your specific needs.