NumPy: Add two arrays A and B of sizes (3,3) and (,3)

Last update on April 26 2025 12:38:17 (UTC/GMT +8 hours)

Add Arrays A (3,3) and B (,3)

Write a NumPy program to add two arrays A and B of sizes (3,3) and (,3).

Pictorial Presentation:

Sample Solution:

Python Code:

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

# Creating a 3x3 array filled with ones
A = np.ones((3, 3))

# Creating a 1-dimensional array containing values from 0 to 2
B = np.arange(3)

# Displaying a message indicating the original arrays will be printed
print("Original array:")
print("Array-1")

# Printing the 3x3 array 'A'
print(A)

print("Array-2")

# Printing the 1-dimensional array 'B'
print(B)

# Displaying a message indicating the addition operation will be performed between arrays 'A' and 'B'
print("A + B:")

# Performing element-wise addition between array 'A' (3x3) and array 'B' (1x3) and storing the result in 'new_array'
new_array = A + B

# Printing the resulting array obtained by adding 'A' and 'B'
print(new_array) 

Sample Output:

Original array:
Array-1
[[1. 1. 1.]
 [1. 1. 1.]
 [1. 1. 1.]]
Array-2
[0 1 2]
A + B:
[[1. 2. 3.]
 [1. 2. 3.]
 [1. 2. 3.]]

Explanation:

In the above exercise -

A = np.ones((3,3)): The current line creates a 2-dimensional NumPy array ‘A’ with shape (3, 3) where all the elements are equal to 1.

B = np.arange(3): The current line creates a 1-dimensional NumPy array ‘B’ with elements from 0 to 2.

new_array = A + B: This line performs an element-wise addition between arrays ‘A’ and ‘B’. Since their shapes are different, NumPy uses broadcasting to match their shapes. In this case, array B is broadcasted along the rows to match the shape of array A.

print(new_array): Finally print() function prints the ‘new_array’.

For more Practice: Solve these Related Problems:

• Write a NumPy program to add a (3,3) array to a (3,) vector using broadcasting and verify the element-wise sum.
• Create a function that takes two arrays of these shapes and returns their sum, ensuring proper broadcasting.
• Test the addition operation on arrays with different constant values and verify the result matches expectations.
• Implement a solution that demonstrates the broadcasting rules by explicitly reshaping the vector before addition.

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