hstack and vstack in numpy | vstack vs hstack

In this numpy tutorial, we will discuss about:

• What is stacking?
• hstack arrays in numpy,
• vstack in numpy,
• vstack and hstack in numpy,

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Before we move ahead to learn about method hstack in numpy, that will help to stack the arrays horizontally as well as vertically in python, lets create one numpy array.

 

numpy stands for numeric python which is used to perform mathematical operations on arrays.

It is a module in which we have to import from the python. 

Syntax to import:

import numpy

We can also use alias for the module 

For example,

import numpy as np

We can directly use np to call the numpy module.

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Create Numpy Array

An array is an one dimensional data structure used to store single data type data.

I.E It will only store all integer data or all string type data.or all float type data.

We can create an numpy array by using array() function.

Syntax:

numpy.array(elements)

where, elements are the input data elements.

 

What is stacking?

Stacking means placing elements from two or more arrays.

So there are two possibilities:

1. one is horizontal stacking and
2. other is vertical stacking.

Lets see how to use hstack arrays in numpy.

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Scenario 1 : Horizontal Stacking using hstack in numpy

We can make a horizontal stacking using hstack() method.

Syntax:

numpy.hstack((array_data1, array_data2))

where,

1. array_data1 is the first numpy input array
2. array_data2 is the second numpy input array

Example: hstack command in numpy

In this hstack arrays in numpy example, we are stacking two numpy arrays horizontally.

#importing the numpy module
import numpy 


#create an array with 8 elements - integer type 
array_data1=numpy.array([34,56,43,22,45,6,54,2])

#actual array1
print(array_data1)

#create an array with 8 elements - integer type 
array_data2=numpy.array([1,2,3,4,5,6,7,8])

#actual array2
print(array_data2)

print()

print(numpy.hstack((array_data1, array_data2)))

Output: hstack command in numpy result

Displaying the actual numpy arrays and horizontal stacked arrays.

[34 56 43 22 45  6 54  2]
[1 2 3 4 5 6 7 8]

[34 56 43 22 45  6 54  2  1  2  3  4  5  6  7  8]

Now lets see how to use vstack in numpy.

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Scenario 2 : Vertical Stacking using vstack in numpy

We can make a vertical stacking using vstack() method or vstack in numpy.

Syntax:

numpy.vstack((array_data1, array_data2))

where,

1. array_data1 is the first numpy input array
2. array_data2 is the second numpy input array

Example: vstack in numpy array

In this vstack in numpy array example, we are stacking two numpy arrays vertically.

#importing the numpy module
import numpy 


#create an array with 8 elements - integer type 
array_data1=numpy.array([34,56,43,22,45,6,54,2])

#actual array1
print(array_data1)

#create an array with 8 elements - integer type 
array_data2=numpy.array([1,2,3,4,5,6,7,8])

#actual array2
print(array_data2)

print()

#vertical stacking
print(numpy.vstack((array_data1, array_data2)))

Output: vstack in numpy array result

Displaying the actual numpy arrays and vertical stacked arrays.

[34 56 43 22 45  6 54  2]
[1 2 3 4 5 6 7 8]

[[34 56 43 22 45  6 54  2]
 [ 1  2  3  4  5  6  7  8]]

Since we have seen both method so we can easily compare vstack and hstack in numpy or vstack vs hstack.