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

Last update on August 29 2025 12:49:30 (UTC/GMT +8 hours)

Extract First & Second Elements of First Two Rows

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

Pictorial Presentation:

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

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 (first and second elements of the first and second rows)
print("\nExtracted data: First and second elements of the first and second rows")

# Using slicing to extract the first two rows and first two columns (0:2 refers to 0th and 1st indices)
print(arra_data[0:2, 0:2])

Sample Output:

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

Extracted data: First and second elements of the first and second rows 
[[0 1]
 [4 5]]

Explanation:

arra_data = np.arange(0, 16).reshape((4, 4)): It 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): This line prints the ‘arra_data’ array.

print(arra_data[0:2, 0:2]): It prints a subarray of ‘arra_data’ containing the first two rows and the first two columns. The slicing syntax 0:2 indicate elements from index 0 (inclusive) to index 2 (exclusive).

For more Practice: Solve these Related Problems:

Write a NumPy program to extract the first two elements from the first and second rows of a 4x4 array.
Create a function that slices a 2D array to return a sub-array consisting of selected rows and columns.
Test the extraction using both direct slicing and advanced indexing methods for verification.
Implement a solution that reshapes the resulting sub-array to ensure it maintains a 2D structure.

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