How to convert a 2D NumPy array to a nested Python list and print it?

Last update on April 29 2025 12:54:32 (UTC/GMT +8 hours)

10. 2D Array to Nested List Conversion

Write a NumPy program to convert a 2D NumPy array to a nested Python list and print the list.

Sample Solution:

Python Code:

import numpy as np

# Create a 2D NumPy array
array_2d = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
print("Original 2D NumPy array:",array_2d)
print("Type:",type(array_2d))
# Convert the 2D NumPy array to a nested Python list
nested_list = array_2d.tolist()
print("\n2D NumPy array to a nested Python list:")
# Print the nested Python list
print(nested_list)
print("Type:",type(nested_list))

Output:

Original 2D NumPy array: [[1 2 3]
 [4 5 6]
 [7 8 9]]
Type: <class 'numpy.ndarray'>

2D NumPy array to a nested Python list:
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
Type: <class 'list'>

Explanation:

Import NumPy Library: Import the NumPy library to work with NumPy arrays.
Create 2D NumPy Array: Define a 2D NumPy array with elements organized in rows and columns.
Convert to Nested List: Use the tolist() method of the NumPy array to convert it into a nested Python list.
Print Nested List: Output the resulting nested Python list to verify the conversion.

For more Practice: Solve these Related Problems:

Write a Numpy program to convert a 2D NumPy array into a nested Python list and then flatten it back into a 1D list using recursion.
Write a Numpy program to convert a 2D array to a nested list and then filter rows based on a condition applied to list elements.
Write a Numpy program to convert a transposed 2D NumPy array to a nested list and then reassemble the original array structure.
Write a Numpy program to convert a 2D NumPy array with mixed numeric types into a nested list and then cast all elements to float.

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