NumPy: Extract second and third elements of the second and third rows from a given (4x4) array

Last update on August 29 2025 12:46:01 (UTC/GMT +8 hours)

Extract Second & Third Elements of Second & Third Rows

Write a NumPy program to extract the second and third elements of the second and third rows from a given (4x4) array.

Pictorial Presentation:

Sample Solution:

Python Code:

# Importing the NumPy library and aliasing it as 'np'
import numpy as np

# Creating a NumPy array 'arra_data' containing integers from 0 to 15 and reshaping it into a 4x4 matrix
arra_data = np.arange(0, 16).reshape((4, 4))

# Displaying a message indicating the original array will be printed
print("Original array:")

# Printing the original 4x4 array 'arra_data'
print(arra_data)

# Displaying a message indicating the extracted data (Second and third elements of the second and third rows)
print("\nExtracted data: Second and third elements of the second and third rows")

# Using slicing to extract a sub-array containing the second and third elements of the second and third rows
print(arra_data[1:3, 1:3]) 

Sample Output:

Original array:
[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]
 [12 13 14 15]]

Extracted data: Second and third elements of the second and third rows
[[ 5  6]
 [ 9 10]]

Explanation:

arra_data = np.arange(0, 16).reshape((4, 4)): This line creates a 1-dimensional NumPy array with elements from 0 to 15 (excluding 16) using np.arange(0, 16) and then reshapes it into a 2-dimensional array with 4 rows and 4 columns using .reshape((4, 4)).

print(arra_data[[1, 3], [0, 3]]): It prints specific elements of ‘arra_data’ by selecting elements with row indices 1 and 3 and column indices 0 and 3. The indexing [1, 3] selects the second and fourth rows, and [0, 3] selects the first and fourth columns.

For more Practice: Solve these Related Problems:

• Write a NumPy program to extract the second and third elements from the second and third rows of a 4x4 array using slicing.
• Create a function that returns a submatrix from selected rows and specific column ranges.
• Test the extraction by comparing the output with a manually constructed sub-array for accuracy.
• Implement an alternative approach using np.ix_ to generate the required indices and validate the result.

Go to:

• NumPy Array Exercises Home ↩
• NumPy Exercises Home ↩

PREV : Extract First Element of Second Row & Fourth of Fourth Row
NEXT : Extract First, Third, Fifth Elements of Third/Fifth Rows of 6x6 Array

Python-Numpy Code Editor: