Python argparse ignore unrecognised arguments

python argparse optparse
joedborg picture joedborg · Oct 10, 2012 · Viewed 61.4k times · Source

Optparse, the old version just ignores all unrecognised arguments and carries on. In most situations, this isn't ideal and was changed in argparse. But there are a few situations where you want to ignore any unrecognised arguments and parse the ones you've specified.

For example:

parser = argparse.ArgumentParser()
parser.add_argument('--foo', dest="foo")
parser.parse_args()

$python myscript.py --foo 1 --bar 2
error: unrecognized arguments: --bar

Is there anyway to overwrite this?

Answer

unutbu picture unutbu · Oct 10, 2012

Replace

args = parser.parse_args()

with 

args, unknown = parser.parse_known_args()

For example,

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--foo')
args, unknown = parser.parse_known_args(['--foo', 'BAR', 'spam'])
print(args)
# Namespace(foo='BAR')
print(unknown)
# ['spam']

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