Numpy append() function merges two arrays and returns a new array, and the original array remains unchanged.
Append to numpy array
To append elements to a numpy array in Python, use the np.append() method. The np.append() is a numpy library function that appends values to the end of an array.
Syntax
numpy.append(array, values, axis = None)Parameters
The np.append() function takes three arguments.
- array: It is an input array.
- values: To be appended to the array.
- axis: The axis along which the append operation is to be done.
Return value
The np.append() function returns a copy of the array with values appended to the axis.
Example
import numpy as np
array_one = np.arange(4)
print("First array : ", array_one)
print("Shape : ", array_one.shape)
array_two = np.arange(7, 11)
print("\nSecond array : ", array_two)
print("Shape : ", array_two.shape)
array_final = np.append(array_one, array_two)
print("\nFinal Array : ", array_final)Output
First array : [0 1 2 3]
Shape : (4,)
Second array : [ 7 8 9 10]
Shape : (4,)
Final Array : [ 0 1 2 3 7 8 9 10]We appended the second array to the first one and returned the new one with combined values.
ValueError: all the input arrays must have same number of dimensions
The ValueError: all the input arrays must have same number of dimensions error occurs when you are trying to append an array to a different shape of the array. Both arrays should have the same shape.
import numpy as np
array_one = np.array([[21, 30],[19, 46]])
array_two = np.array([8, 9, 10, 11, 12])
final_array = np.append(array_one, array_two, axis=0)
print(final_array)Output
ValueError: all the input arrays must have same number of dimensions, but the array at index 0 has 2 dimension(s) and the array at index 1 has 1 dimension(s)And we are getting the ValueError because the input arrays did not have the same number of dimensions.
That’s it.
