NumPy Append Function

Introduction

In this lab, you will learn how to use the NumPy append() function. NumPy is a Python library for numerical processing and it provides an efficient and convenient way to handle arrays, matrices, and multi-dimensional data. The append() function in NumPy adds new data to an existing array.

VM Tips

After the VM startup is done, click the top left corner to switch to the Notebook tab to access Jupyter Notebook for practice.

Sometimes, you may need to wait a few seconds for Jupyter Notebook to finish loading. The validation of operations cannot be automated because of limitations in Jupyter Notebook.

If you face issues during learning, feel free to ask Labby. Provide feedback after the session, and we will promptly resolve the problem for you.

Skills Graph

Import NumPy library

The first step is to import the NumPy library using the import statement. This will make all the functions in the NumPy library accessible to us in our code.

import numpy as np

Create two arrays

Create two arrays that we will use in the examples to follow.

a = np.array([[1, 2, 3], [7, 8, 9]])
b = np.array([[11, 21, 31], [42, 52, 62]])

Use append() function with axis=None

The numpy.append() function is used to append values to an existing array. When axis parameter is not defined, the input arrays are flattened before appending. In the below example, we are appending arrays a and b.

c = np.append(a,b)
print("The resultant array after appending a & b:\n",c)

Use append() function with axis=0

The axis=0 parameter specifies that the appending should be done along the rows. In this next example, we are appending arrays a and b along axis 0.

c = np.append(a,b,axis=0)
print("The resultant array after appending a & b along axis 0:\n",c)

Use append() function with axis=1

The axis=1 parameter specifies that the appending should be done along the columns. In this next example, we are appending arrays a and b along axis 1.

c = np.append(a,b,axis=1)
print("The resultant array after appending a & b along axis 1:\n",c)

Summary

In this lab, you learned how to use the NumPy append() function to add values to an existing array. The append() function appends values to an array along a specified axis and returns a new array without modifying the original array. You can use the axis parameter to indicate where the new values should be added. When axis is not defined, the arrays are flattened before append.

Congratulations! You now have the knowledge to use the NumPy append() function to append values to an existing array.