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python-3.xwarningsjupyter-notebook
Marnix
Marnix

Reputation: 779

turn warning off in a cell jupyter notebook

I get some useless warnings in python 3 jupyter notebook. I want to turn off these warnings in a particular cell only, so not in the rest of the ipynb-file. Does someone know how to do this?

Upvotes: 56

Views: 51866

Answers (6)

irene
irene

Reputation: 2243

I added %%capture --no-stdout as the first line of the cell. That worked for me. Strangely, %%capture --no-stderr showed only the warnings, but none of the desired output.

Upvotes: 2

mins
mins

Reputation: 7504

Solutions:

Usually there is no need to extend the effect to the whole cell, as this may hide some other useful message, so use a context manager to ignore the warnings:

with warnings.catch_warnings():
    warnings.simplefilter('ignore')
    # Your problematic instruction(s) here

If there are good reasons to protect the whole cell then simply prevent the stderr stream to be displayed in the cell output area by inserting the capture "magic":

%%capture --no-stderr

at the top of the cell (rather than indenting all lines).

Explanations:

The most logical way is to insert the code triggering a warning within a context manager introduced by keyword with. It switches off and restore the warning system prior and after the problematic code

Python provides such context manager as warnings.catch_warnings:

A context manager that copies and, upon exit, restores the warnings filter and the showwarning() function. If the record argument is False (the default) the context manager returns None on entry. If record is True, a list is returned that is progressively populated with objects as seen by a custom showwarning() function (which also suppresses output to sys.stdout).

You also need to register a filter to react to each warning captured by the context manager, else the default filter remains active.

Python provides the warnings.simplefilter which:

Insert a simple entry into the list of warnings filter specifications

It registers some action (ignore for no action, always to print the warning message, etc, see full description).

Example:

import warnings, math
import numpy as np

# We want to compute the logs of this sequence.
# But log isn't defined for values <= 0
s = [-1, 5, 2, 0]

with warnings.catch_warnings():
    warnings.simplefilter('ignore')
    r = np.log(s)

print(r)

Upvotes: 16

Rosa Aghdam
Rosa Aghdam

Reputation: 131

I tried many different commands, but this one works for me

import warnings

warnings.filterwarnings('ignore')

Upvotes: 4

happyhuman
happyhuman

Reputation: 1651

For me these two lines do the job:

import warnings
warnings.filterwarnings('ignore')

Upvotes: 2

Joshua Dempster
Joshua Dempster

Reputation: 595

Write %%capture as the first line of the cell to catch cell output. You can use the options --no-stderr, --no-stdout, --no-display, and --output to control which cell outputs will be caught. See more details here.

Upvotes: 38

typingduck
typingduck

Reputation: 835

Normally I want to keep stdout open for printing so I find using catch_warnings like this better:

import warnings

def action_with_warnings():
    warnings.warn("should not appear")

with warnings.catch_warnings(record=True):
    action_with_warnings()

It has the disadvantage of storing the warnings in memory, but it is normally not a significant overhead and worth the simplicity. Even within a single cell I find having fine grained control means warnings I do care about are not accidentlly missed.

Upvotes: 11

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