Check if a value exists in a NumPy Array

This tutorial will discuss about unique ways to check if a value exists in a NumPy array in Python.

Table Of Contents

Technique 1: Using “in” keyword

Python provides an “in” keyword to check if a sequence contains a value or not. We can use that to check if a NumPy Array contains a value or not. Suppose we have a NumPy Array,

import numpy as np

arr = np.array([34, 23, 45, 28, 90, 11, 34])

value = 90

Now we want to check if value “90” exists in this NumPy array or not. For that we can apply the “in” keyword. Like this,

value in arr

It will return True if the given value exists in the given NumPy array “arr”.

Let’s see the complete example,

import numpy as np

# A NumPy Array
arr = np.array([34, 23, 45, 28, 90, 11, 34])

value = 90

# Check if a value exists in numpy array
if value in arr:
    print("Yes, value exists in the array")
else:
    print("No, value does not exists in the array")

Output

Yes, value exists in the array

Technique 2: Using isin() and any() methods

The numpy.isin() method excepts a NumPy array and a value as arguments, and returns a boolean array. Each True value in the boolean array represents that the corresponding element in the given array matches with the given value. Then we can apply the numpy.any() method on this boolean numpy array, to check if it contains any True value. If Yes, then it means that the given value exists in the NumPy Array.

Let’s see the complete example,

import numpy as np

# A NumPy Array
arr = np.array([34, 23, 45, 28, 90, 11, 34])

value = 90

# Check if a value exists in numpy array
if np.isin(value, arr).any():
    print("Yes, value exists in the array")
else:
    print("No, value does not exists in the array")

Output

Yes, value exists in the array

Summary

We learned about two different ways to check if a NumPy Array contains a given value or not in Python. Thanks.