How to disable Python warnings?

Question

I am working with code that throws a lot of (for me at the moment) useless warnings using the warnings library. Reading (/scanning) the documentation I only found a way to disable warnings for single functions. But I don't want to change so much of the code.

Is there a flag like python -no-warning foo.py?

What would you recommend?

Answer 1

Look at the Temporarily Suppressing Warnings section of the Python docs:

If you are using code that you know will raise a warning, such as a deprecated function, but do not want to see the warning, then it is possible to suppress the warning using the catch_warnings context manager:

import warnings

def fxn():
    warnings.warn("deprecated", DeprecationWarning)

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    fxn()

I don't condone it, but you could just suppress all warnings with this:

import warnings
warnings.filterwarnings("ignore")

Ex:

>>> import warnings
>>> def f():
...     print('before')
...     warnings.warn('you are warned!')
...     print('after')
...
>>> f()
before
<stdin>:3: UserWarning: you are warned!
after
>>> warnings.filterwarnings("ignore")
>>> f()
before
after

Answer 2

There's the -W option.

python -W ignore foo.py

Answer 3

You can also define an environment variable (new feature in 2010 - i.e. python 2.7)

export PYTHONWARNINGS="ignore"

Test like this: Default

$ export PYTHONWARNINGS="default"
$ python
>>> import warnings
>>> warnings.warn('my warning')
__main__:1: UserWarning: my warning
>>>

Ignore warnings

$ export PYTHONWARNINGS="ignore"
$ python
>>> import warnings
>>> warnings.warn('my warning')
>>> 

For deprecation warnings have a look at how-to-ignore-deprecation-warnings-in-python

Copied here...

From documentation of the warnings module:

 #!/usr/bin/env python -W ignore::DeprecationWarning

If you're on Windows: pass -W ignore::DeprecationWarning as an argument to Python. Better though to resolve the issue, by casting to int.

(Note that in Python 3.2, deprecation warnings are ignored by default.)

Or:

import warnings

with warnings.catch_warnings():
    warnings.filterwarnings("ignore", category=DeprecationWarning)
    import md5, sha

yourcode()

Now you still get all the other DeprecationWarnings, but not the ones caused by:

import md5, sha

Answer 4

Not to make it complicated, just use these two lines

import warnings
warnings.filterwarnings('ignore')

Answer 5

If you don't want something complicated, then:

import warnings
warnings.filterwarnings("ignore", category=FutureWarning)

Answer 6

When all else fails use this: https://github.com/polvoazul/shutup

pip install shutup

then add to the top of your code:

import shutup; shutup.please()

---

Disclaimer: I am the owner of that repository. I wrote it after the 5th time I needed this and couldn't find anything simple that just worked.

Answer 7

This is an old question but there is some newer guidance in PEP 565 that to turn off all warnings if you're writing a python application you should use:

import sys
import warnings

if not sys.warnoptions:
    warnings.simplefilter("ignore")

The reason this is recommended is that it turns off all warnings by default but crucially allows them to be switched back on via python -W on the command line or PYTHONWARNINGS.

Answer 8

If you know what are the useless warnings you usually encounter, you can filter them by message.

import warnings

#ignore by message
warnings.filterwarnings("ignore", message="divide by zero encountered in divide")

##part of the message is also okay
warnings.filterwarnings("ignore", message="divide by zero encountered") 
warnings.filterwarnings("ignore", message="invalid value encountered")

Answer 9

import sys
if not sys.warnoptions:
    import warnings
    warnings.simplefilter("ignore")

Change ignore to default when working on the file or adding new functionality to re-enable warnings.

Answer 10

I realise this is only applicable to a niche of the situations, but within a numpy context I really like using np.errstate:

np.sqrt(-1)

__main__:1: RuntimeWarning: invalid value encountered in sqrt
nan

However, using np.errstate:

with np.errstate(invalid='ignore'):
    np.sqrt(-1)

nan

The best part being you can apply this to very specific lines of code only.

Answer 11

---

More pythonic way to ignore WARNINGS

---

Since 'warning.filterwarnings()' is not suppressing all the warnings, i will suggest you to use the following method:

import logging
    
for name in logging.Logger.manager.loggerDict.keys():
    logging.getLogger(name).setLevel(logging.CRITICAL)

#rest of the code starts here...

OR,

If you want to suppress only a specific set of warnings, then you can filter like this:

import logging
    
for name in logging.Logger.manager.loggerDict.keys():
    if ('boto' in name) or ('urllib3' in name) or ('s3transfer' in name) or ('boto3' in name) or ('botocore' in name) or ('nose' in name):
            logging.getLogger(name).setLevel(logging.CRITICAL)

#rest of the code starts here...

Answer 12

For example you can ignore this warning:

InsecureRequestWarning: Unverified HTTPS request is being made to host...

import warnings

warnings.filterwarnings(
    action="ignore",
    message=".*Unverified HTTPS.*",
)

Answer 13

I have written a decorator that makes it very easy to ignore warnings only in specific function definitions:

import functools
import warnings

from typing import Callable

def ignore_warnings(category: Warning):
    def ignore_warnings_decorator(func: Callable):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            with warnings.catch_warnings():
                warnings.simplefilter("ignore", category=category)
                return func(*args, **kwargs)
        return wrapper
    return ignore_warnings_decorator

Example usage:

@ignore_warnings(category=DeprecationWarning)
def foo() -> None:
    # imagine this function below would throw a deprecation
    # warning that we willfully want to ignore because we know better:
    bar()

Answer 14

Warnings are output via stderr and the simple solution is to append to the command.

2> /dev/null

Alternatively, redirect errors to a file, so they are retained without dirtying the console output.

2> my-cli-errors.log