NumPy: Concatenate two 2-dimensional arrays

Last update on August 29 2025 12:46:42 (UTC/GMT +8 hours)

Concatenate 2D Arrays

Write a NumPy program to concatenate two 2-dimensional arrays.
Sample arrays: ([[0, 1, 3], [5, 7, 9]], [[0, 2, 4], [6, 8, 10]]

Pictorial Presentation:

Python NumPy: Concatenate two 2-dimensional arrays

Sample Solution:

Python Code:

# Importing the NumPy library with an alias 'np'
import numpy as np

# Creating two NumPy arrays 'a' and 'b'
a = np.array([[0, 1, 3], [5, 7, 9]])
b = np.array([[0, 2, 4], [6, 8, 10]])

# Concatenating arrays 'a' and 'b' along the second axis (horizontally) using np.concatenate
c = np.concatenate((a, b), 1)

# Printing the concatenated array 'c'
print(c)

Sample Output:

[[ 0  1  3  0  2  4]                                                   
 [ 5  7  9  6  8 10]]

Explanation:

In the above code –

‘a = np.array([[0, 1, 3], [5, 7, 9]])’ creates a 2D array a with shape (2, 3).

‘b = np.array([[0, 2, 4], [6, 8, 10]])’ creates another 2D array b with shape (2, 3).

c = np.concatenate((a, b), 1): The np.concatenate() function is used to join the two arrays ‘a’ and ‘b’ along the second axis (axis=1). The resulting array ‘c’ has the shape (2, 6), with the columns of ‘b’ appended to the columns of ‘a’.

For more Practice: Solve these Related Problems:

Write a NumPy program to horizontally concatenate two 2D arrays using np.concatenate and verify the combined shape.
Implement vertical concatenation of two arrays and validate the resulting dimensions.
Concatenate multiple 2D arrays along a new axis and then merge them back to a single array.
Create a function that accepts a list of 2D arrays and concatenates them along a specified axis.

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