Searching in Numpy Array

What is Array Search?

Sometimes we need to find a specific value or check a condition inside an array.

For example:

• Find where 25 is present.
• Find all even numbers.
• Find all odd numbers.
• Find the correct position to insert a value into a sorted array.

NumPy provides different functions to perform these searching tasks.

1. np.where()

Description

np.where() is used to search an array based on a condition.

Instead of returning the values, it returns the indexes where the condition becomes True.

Syntax

np.where(condition)

The condition can be:

• ==
• >
• <
• >=
• <=
• %

Example 1: Find the index of a value

import numpy as np

arr = np.array([12, 25, 18, 25, 30, 25])
result = np.where(arr == 25)
print(result)

Output

(array([1, 3, 5]),)

Explanation