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NumPy vstack

By Princy VictorPrincy Victor

NumPy vstack

Definition of NumPy vstack

In python, numpy.vstack() is a function that helps to stack the input array sequence vertically in order to create a single array. The arrangement will be in row-wise. It is similar to concatenation along the axis 1 after 1-Dimensional arrays of (N) shape have been reshaped to the format (1,N). This function can be used to create arrays with up to 3- dimensions. Let us see more of this function in the following sessions.

Syntax:

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Below is the syntax of numpyvstack function.

numpy.vstack(tup)

Parameters:

  • tup: It is a sequence of n arrays. This tuple consists of arrays that have to be stacked. Arrays should have the shape same along all but the axis 1.
  • Return Value of This Function: Return value will be stacked in an array. That is an array that is stacked of the input arrays.

How does vstack Function Work in NumPy?

Using the vstack() function, items of arrays are arranged vertically. Suppose array 1 has elements [22, 32, 43] and array 2 has elements [546, 55, 556]. The two arrays can be arranged vertically using the function vstack(( arr1 , arr2 ) ) where arr1 and arr2 are array 1 and array 2 respectively.

Examples of NumPy vstack

Let us see some sample programs on the vstack() function using python.

Example #1

Python program to arrange two arrays vertically using vstack.

Code:

import numpy as np
arr1 = np.array( [ 22 , 32 , 43 ] )
print ("array 1 is : \n", arr1)
arr2 = np.array( [ 546 , 55 , 556 ] )
print ("array 2 is  : \n", arr2)
arrout = np.vstack( ( arr1 , arr2 ) )
print ( "arrays arranged vertically :\n ", arrout)

Output:

NumPy vstack-1.1

In this program, two arrays are created and they are arranged vertically using the vstack function.

Example #2

Python program to arrange two arrays with multiple elements vertically using vstack.

Code:

import numpy as np
arr1 = np.array( [ [ 22 , 32 , 43 ] , [11 , 52 , 67 ] ] )
print ("array 1 is : \n", arr1)
arr2 = np.array( [ [ 546 , 55 , 556 ] , [131 , 252 , 167 ] ] )
print ("array 2 is  : \n", arr2)
arrout = np.vstack( ( arr1 , arr2 ) )
print ( "arrays arranged vertically :\n ", arrout)

Output:

NumPy vstack-1.2

Unlike program 1,in this program, two arrays are created with different elements and they are arranged vertically using the vstack function.

Example #3

Python program to arrange two arrays given as input by the user where array 1 is input and array 2 is already in the program.

Code:

import numpy as np
# create an empty list
li = []
n = int(input("Enter the no. of elements to be given as input: "))
for it in range(0, n):
    items = int(input())
    li.append(items)
print ("array 1 is : \n", li)
arr2 = np.array( [ 546 , 55 , 556 ] )
print ("array 2 is  : \n", arr2)
# arranging two arrays vertically
arrout = np.vstack( ( li , arr2 ) )
print ( "arrays arranged vertically :\n ", arrout)

Output:

Output-1.3

In this program, the first array is given as input by the user, and the second array is already available in the program. Then, it is arranged vertically using the function vstack().

Example #4

Python program to arrange two arrays given as input by the user.

Code:

import numpy as np
# array 1 creation
li = []
n = int(input("Enter the no. of elements to be given as input to array 1: "))
for it in range(0, n):
    items = int(input())
    li.append(items)
print ("array 1 is : \n", li)
li2 = []
# no: of elements to be given as input
nn = int(input("Enter the no. of elements to be given as input to array 2: "))
# iterate the loop till the given range
for itr in range(0, nn):
    itemss = int(input())
    li2.append(itemss)
print ("array 2 is  : \n", li2)
# arranging two arrays vertically
arrout = np.vstack( ( li , li2 ) )
print ( "arrays arranged vertically :\n ", arrout)

Output:

Output-1.4

In this program, both the first array and second array is given as input by the user. Then, it is arranged vertically using the function vstack().

Example #5

Python program to arrange multiple arrays given as input by the user.

Code:

import numpy as np
# array 1 creation
# create an empty list
li = []
# no: of elements to be given as input
n = int(input("Enter the no. of elements to be given as input to array 1: "))
# iterate the loop till the given range
for it in range(0, n):
    items = int(input())
    li.append(items)
print ("array 1 is : \n", li)
# create an empty list
li2 = []
# no: of elements to be given as input
nn = int(input("Enter the no. of elements to be given as input to array 2: "))
# iterate the loop till the given range
for itr in range(0, nn):
    itemss = int(input())
    li2.append(itemss)
print ("array 2 is  : \n", li2)
# create an empty list
li3 = []
# no: of elements to be given as input
no = int(input("Enter the no. of elements to be given as input to array 3: "))
# iterate the loop till the given range
for itrt in range(0, no):
    itemms = int(input())
    li3.append(itemms)
print ("array 3 is  : \n", li3)
# arranging two arrays vertically
arrout = np.vstack( ( li , li2, li3 ) )
print ( "arrays arranged vertically :\n ", arrout)

Output:

Output-1.5

In this program, multiple arrays are given as input by the user. Then, it is arranged vertically using the function vstack().

Conclusion

numpy.vstack() is a function that helps to stack the input array sequence vertically in order to create a single array. In this article, different aspects such as syntax, working, and examples of the vstack function is explained in detail.

Recommended Articles

This is a guide to NumPy vstack. Here we also discuss the definition and how does vstack function work in numpy along with different examples and its code implementation. You may also have a look at the following articles to learn more –

  1. NumPy Arrays
  2. NumPy Ndarray
  3. String Array in Python
  4. Matrix in NumPy
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