Stack Arrays Horizontally - NumPy
NumPy - Stack arrays horizontally
To stack two or more arrays horizontally in NumPy, we can use numpy.hstack()
function. Pass the arrays in a tuple as argument to hstack() function.
For example, we want to stack arrays a
, b
, and c
horizontally using hstack() function, use the following expression.
numpy.hstack((a, b, c))
Examples
1. Stack two arrays horizontally
In the following program, we take two numpy arrays and stack them horizontally.
Python Program
import numpy as np
arr1 = np.array([[1, 2], [3, 4]])
arr2 = np.array([[5, 6], [7, 8]])
output = np.hstack((arr1, arr2))
print('array 1\n', arr1)
print('array 2\n', arr2)
print('stacking horizontally...\n', output)
Output
array 1
[[1 2]
[3 4]]
array 2
[[5 6]
[7 8]]
stacking horizontally...
[[1 2 5 6]
[3 4 7 8]]
2. Stack three arrays horizontally
In the following program, we take two numpy arrays and stack them horizontally.
Python Program
import numpy as np
arr1 = np.array([[1, 2], [3, 4]])
arr2 = np.array([[5, 6], [7, 8]])
arr3 = np.array([[9, 10],[11, 12]])
output = np.hstack((arr1, arr2, arr3))
print('array 1\n', arr1)
print('array 2\n', arr2)
print('array 3\n', arr3)
print('stacking horizontally...\n', output)
Output
array 1
[[1 2]
[3 4]]
array 2
[[5 6]
[7 8]]
array 3
[[ 9 10]
[11 12]]
stacking horizontally...
[[ 1 2 5 6 9 10]
[ 3 4 7 8 11 12]]
Summary
In this NumPy Tutorial, you learned how to access elements of a numpy array using indexing operator.