Blog

In this chapter, we will discuss about NumPy – append. This function adds values at the end of an input array. The append operation is not in place, a new array is allocated. Also, the dimensions of the input arrays must match otherwise ValueError will be generated.

The function takes the following parameters.

numpy.append(arr, values, axis)

Where,

Example Of NumPy append

import numpy as np 
a = np.array([[1,2,3],[4,5,6]]) 

print 'First array:' 
print a 
print '\n'  

print 'Append elements to array:' 
print np.append(a, [7,8,9]) 
print '\n'  

print 'Append elements along axis 0:' 
print np.append(a, [[7,8,9]],axis = 0) 
print '\n'  

print 'Append elements along axis 1:' 
print np.append(a, [[5,5,5],[7,8,9]],axis = 1)

Its output would be as follows −

First array:
[[1 2 3]
 [4 5 6]]

Append elements to array:
[1 2 3 4 5 6 7 8 9]

Append elements along axis 0:
[[1 2 3]
 [4 5 6]
 [7 8 9]]

Append elements along axis 1:
[[1 2 3 5 5 5]
 [4 5 6 7 8 9]]