How to disable Python warnings?

There are times when the compiler informs the user of a condition in the program while the code is being executed. When it is necessary to advise the user of a program condition that (usually) doesn’t require raising an exception or terminating the program, warning messages are typically sent. Mostly, these warnings are descriptive of some underlying fault at work. But sometimes, they may not be required. This article will make you understand how to disable Python warnings in a very simple manner.

What are Python warnings?

Warnings are provided to warn the developer of situations that aren’t necessarily exceptions. Usually, a warning occurs when certain programming elements are obsolete, such as keyword, function or class, etc. A warning in a program is distinct from an error. Python program terminates immediately if an error occurs. Conversely, a warning is not critical. It shows some messages, but the program runs.

Example:

The following is a warning that occurs when the path environment variable does not contain the path to the scripts folder of the Python distribution.

The pip module was reinstalled, and a warning appeared during the process.

Again, the task at hand (reinstalling pip) was successfully completed, but the compiler warned about an irregularity detected in the paths. Regardless of whether the issue is resolved or not, it did not have a direct impact on the task. But this may not always be true.

How to Disable Python Warnings?

There are two ways in which warnings can be ignored:

• Disabling warnings from the code
• Disabling warnings with Command

Disabling warnings from the code

To disable warnings from the code, the use of the warnings module would be made, and all the warnings would be filtered to be ignored. Hence, no warning would appear in the output. First, we will generate code that won’t need to turn off warnings, and then we will generate code that will. The warning is not disabled in the following code:

Python3

import warnings

print('Hello')

# Displaying a warning message
warnings.warn('Error: A warning just appeared')

print('Geeks !')

Output:

In the above code, a self-generated warning message was displayed. Since, by default, the program has warnings enabled, the message was displayed, and the warning appeared. Now, the warnings are disabled, then an attempt to display the warning has been made:

Python3

import warnings

print('Hello')

# Settings the warnings to be ignored
warnings.filterwarnings('ignore')

# This warning won't display due to the disabled warnings
warnings.warn('Error: A warning just appeared')

print('Geeks !')

Output:

The output of the code omitted the warning due to the second statement, which calls the filterwarnings function and passes ignore as an argument. This filters all the warnings occurring during the code to be ignored. Due to this, the warning in the next statement didn’t appear. 

Disabling Python Warnings with Command

In case the contents of the code can’t be modified to integrate the previous method into it, warnings can be disabled from the outside. This is done by passing the ignore argument to the -W switch of the Python compiler. 

-W arg : warning control; arg is action:message:category:module:lineno
        also PYTHONWARNINGS=arg

Hence, by integrating the -W “ignore” string in the command to execute the first code, the warnings in the code could be disabled. The code that is to be run from the command line would be:

py -W "ignore" test.py

The Python interpreter is instructed to disable the warnings before the execution of the test.py file (used in the first example). Similarly, using the following syntax:

py -W "ignore" "_filename_"

Warnings could be ignored during the execution of files containing Python code.