disable warnings in python
Python

How to Disable Warnings in Python: A Step-by-Step Guide

When working with Python, you may encounter messages highlighted in yellow. These are warnings signifying that there might be minor issues within the code which could potentially cause future problems—despite the code being executable.

Warnings serve as useful alerts; however, there are scenarios where you might prefer not to see them.

This article addresses the nature of Python warnings, the reasons for choosing to suppress them, and the methods to effectively do so. The objective is to provide you with clear guidance on handling these notifications according to your project needs.

Python Warnings

In the Python programming language, you might encounter system-generated notifications when your code includes uncommon or potentially problematic elements.

These notifications, known as warnings, function as alerts to highlight specific issues that may not immediately cause errors but could lead to unexpected behaviors or future complications in the codebase.

Notable types of warnings you may come across include:

  • Deprecation Warnings: Indicate that a particular Python feature or function is scheduled to be removed in upcoming versions.
  • Syntax Warnings: Point out unusual, yet valid, code constructs that might not function as you anticipate.

Consider the following code snippet:

import warnings

def fxn():
    warnings.warn("fxn() is deprecated", DeprecationWarning, stacklevel=2)

warnings.simplefilter('always', DeprecationWarning)
fxn()

When executed, the system outputs a DeprecationWarning. Be aware that to receive such warnings in your output, you may need to implement specific filters like warnings.simplefilter('always', DeprecationWarning), as some warnings, particularly DeprecationWarnings, are not displayed by default.

Reasons to Disable Warnings

  • Clarity in Output: Warnings can obscure vital details when working with substantial codebases, distracting you from significant code outputs.
  • Clean Log Files: During script execution, you might prefer a warning-free log to ensure logs remain concise and relevant.

Managing Python Warning Messages

Modifying Warning Output via Module

In Python, managing which warning messages are displayed can be achieved through the warnings module.

You can alter the output by using the code:

import warnings
warnings.filterwarnings("ignore")

This command suppresses all warnings. To target specific warnings, like DeprecationWarning, use:

warnings.filterwarnings("ignore", category=DeprecationWarning)

Adjusting Warning Levels for Script Execution

To run your Python script without warnings appearing, append the -W flag with ignore when executing the script:

python -W ignore your_script.py

Setting Global Warning Preferences

Adjust global warning preferences using the PYTHONWARNINGS environment variable. To avoid all warnings during an active session:

export PYTHONWARNINGS="ignore"
python your_script.py

For a permanent solution across all sessions, introduce the export PYTHONWARNINGS="ignore" to your shell’s startup script like .bashrc.

Risks of Disabling Warnings

Turning off warnings in Python can lead to unforeseen issues. When you suppress specific warnings like DeprecationWarning, it implies that you may be using functionalities scheduled for discontinuation.

Ignoring these cautionary messages could result in your application ceasing to function after an update.

Optimally, you would address the causes of these warnings rather than silencing them. However, scenarios do occur where silent warnings may seem necessary, especially with third-party libraries producing noncritical or uncontrollable warnings. In such instances:

  • Focus on suppressing only the particular warnings that are irrelevant to your application.
  • Refrain from using commands that disable warnings globally, to avoid missing out on other important alerts.

Considerations before suppressing warnings:

  • Warnings signal possible flaws or unexpected behaviors.
  • Silencing can lead to cleaner output during execution.
  • Exercise caution; ensure that you fully understand the implications of ignoring specific warnings.
Posted by
Glenn Yang

I code in Python, JavaScript, and C++; Open-source advocate; Hackathon participant and 'con enjoyer.