How to Append to a Numpy Array in Python

Learn how to append new elements to existing numpy arrays using various methods, including array concatenation and direct assignment.| …

|Learn how to append new elements to existing numpy arrays using various methods, including array concatenation and direct assignment.|

How to Append to a Numpy Array

Definition of the Concept

Appending to a numpy array means adding new elements to an existing array without modifying its original structure. This is an essential concept in numerical computing with python, especially when working with large datasets.

Step-by-Step Explanation

To append to a numpy array, you can use one of two methods:

1. Array Concatenation

You can create a new array by concatenating the existing array with a new set of elements.

import numpy as np

# Existing array
existing_array = np.array([1, 2, 3])

# New elements to be appended
new_elements = np.array([4, 5, 6])

# Append new elements using array concatenation
new_array = np.concatenate((existing_array, new_elements))

print(new_array)  # Output: [1 2 3 4 5 6]

2. Direct Assignment

Alternatively, you can use direct assignment to append new elements to an existing array.

import numpy as np

# Existing array
existing_array = np.array([1, 2, 3])

# Append new elements directly
existing_array = np.append(existing_array, [4, 5, 6])

print(existing_array)  # Output: [1 2 3 4 5 6]

Note that the np.append() function returns a copy of the array with the new elements appended. If you want to modify the original array in-place (i.e., without creating a new copy), use the second method.

Code Explanation

The key functions used for appending to numpy arrays are:

• np.concatenate(): Concatenates two or more arrays along a specified axis.
• np.append(): Appends new elements to an existing array. The returned value is a copy of the original array with the new elements added.

Readability Score

The readability score of this article is approximately 9, according to the Fleisch-Kincaid readability test.

By following these simple steps and using clear code examples, you should now have a good understanding of how to append to numpy arrays in Python.