How to convert a 3D NumPy array to a list of lists of lists?

Last update on April 29 2025 13:00:12 (UTC/GMT +8 hours)

16. 3D Array to Nested List Conversion

Write a NumPy program to convert a 3D NumPy array to a list of lists of lists and print the result.

Sample Solution:

Python Code:

import numpy as np

# Create a 3D NumPy array
array_3d = np.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]])

print("Original 3D NumPy array:",array_3d)
print(type(array_3d))
# Convert the 3D NumPy array to a nested list of lists of lists
list_of_lists = array_3d.tolist()

# Print the list of lists of lists
print("\nlist of lists of lists:")
print(list_of_lists)
print(type(list_of_lists))

Output:

Original 3D NumPy array: [[[ 1  2  3]
  [ 4  5  6]]

 [[ 7  8  9]
  [10 11 12]]]
<class 'numpy.ndarray'>

list of lists of lists:
[[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]]
<class 'list'>

Explanation:

Import NumPy Library: Import the NumPy library to work with arrays.
Create 3D NumPy Array: Define a 3D NumPy array with some example data.
Convert to Nested List: Use the tolist() method of the NumPy array to convert it into a nested list of lists of lists.
Print List of Lists: Output the resulting nested list to verify the conversion.

For more Practice: Solve these Related Problems:

Write a Numpy program to convert a 3D NumPy array into a nested list of lists of lists and then recursively compute the depth of the nested list.
Write a Numpy program to convert a 3D array to a nested list and then flatten it back while preserving the original 3D shape.
Write a Numpy program to convert a 3D NumPy array to a nested list and then apply a custom function to each innermost list.
Write a Numpy program to convert a 3D array into a nested list and then validate element ordering by comparing with the array’s ravelled version.

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