Answers by Sentry

Check for NaN values in Python

David Y.

The Problem

I sometimes see the value NaN (Not a Number) when working with floats in Python. How can I check whether a given value is NaN?

The Solution

The best way to do this is by using the isnan() function from Python’s built-in math library:

import math

nan = float('nan')
zero = 0
one = 1

print(math.isnan(nan))  # will print True
print(math.isnan(zero))  # will print False
print(math.isnan(one))  # will print False

Note that isnan() will throw a TypeError if given a non-numeric value. Thus, a more robust implementation might look like this:

import math

def is_nan(value):
    try:
        return math.isnan(value)
    except TypeError:
        return False

nan = float('nan')
zero = 0
one = 1
hello = "Hello!"

print(is_nan(nan))  # will print True
print(is_nan(zero))  # will print False
print(is_nan(one))  # will print False
print(is_nan(hello))  # will print False

Get Started With Sentry

Get actionable, code-level insights to resolve Python performance bottlenecks and errors.

  1. Create a free Sentry account

  2. Create a Python project and note your DSN

  3. Grab the Sentry Python SDK

pip install --upgrade sentry-sdk
  1. Configure your DSN
import sentry_sdk

sentry_sdk.init(
    "https://<key>@sentry.io/<project>",

    # Set traces_sample_rate to 1.0 to capture 100%
    # of transactions for performance monitoring.
    # We recommend adjusting this value in production.
    traces_sample_rate=1.0,
)

Loved by over 4 million developers and more than 90,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.

learn more about sentryjoin our discord
Share on Twitter
Bookmark this page
Ask a questionJoin the discussion

Related Answers

A better experience for your users. An easier life for your developers.

Try Sentry For FreeRequest a Demo
    TwitterGitHubDribbbleLinkedinDiscord
© 2024 • Sentry is a registered Trademark
of Functional Software, Inc.