NumPy filter array by condition | Example code

Use NumPy extract() or Where() function to filter array by condition.

NumPy filter array by condition example

Simple example code NumPy filter using condition on each element.

Using NumPy.extract:

import numpy as np

na = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
res = np.extract(na % 2 == 0, na)

print(res)

Output:

Using NumPy.where:

import numpy as np

na = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
res = na[np.where(na % 2 == 0)]

print(res)

Output: [ 2 4 6 8 10]

How to efficiently filter elements in a NumPy array by value in Python?

Answer: Use boolean indexing to filter elements in an array by value to filter NumPy Array.

import numpy as np

na = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
res = na[na > 4]

print(res)

Output: [ 5 6 7 8 9 10]

Do comment if you have any doubts or suggestions on this NumPy Array topic.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.