I'm learning basics of Python and got already stuck at the beginning of argparse tutorial. I'm getting the following error:
import argparse
parser = argparse.ArgumentParser()
args = parser.parse_args()
usage: __main__.py [-h] echo
__main__.py: error: unrecognized arguments: -f
An exception has occurred, use %tb to see the full traceback.
SystemExit: 2
a %tb command gives the following output:
SystemExit Traceback (most recent call last)
<ipython-input-16-843cc484f12f> in <module>()
----> 1 args = parser.parse_args()
C:\Users\Haik\Anaconda2\lib\argparse.pyc in parse_args(self, args, namespace)
1702 if argv:
1703 msg = _('unrecognized arguments: %s')
-> 1704 self.error(msg % ' '.join(argv))
1705 return args
1706
C:\Users\Haik\Anaconda2\lib\argparse.pyc in error(self, message)
2372 """
2373 self.print_usage(_sys.stderr)
-> 2374 self.exit(2, _('%s: error: %s\n') % (self.prog, message))
C:\Users\Haik\Anaconda2\lib\argparse.pyc in exit(self, status, message)
2360 if message:
2361 self._print_message(message, _sys.stderr)
-> 2362 _sys.exit(status)
2363
2364 def error(self, message):
SystemExit: 2
How could I fix this problem?
argparse is a module designed to parse the arguments passed from the command line, so for example if you type the following at a command prompt:
$ python my_programme.py --arg1=5 --arg2=7
You can use argparse to interpret the --arg1=5 --arg2=7 part. If argparse thinks the arguments are invalid, it exits, which in general is done in python by calling sys.exit() which raises the SystemExit error, which is what you're seeing.
So the problem is you're trying to use argparse from an interactive interpreter (looks like ipython), and at this point the programme has already started, so the args should have already been parsed.
To try it properly create a separate python file such as my_programme.py and run it using python from a command line, as I illustrated.
[quick solution] Add an dummy parser argument in the code
parser.add_argument('-f')
had run into a similar issue. adding these lines fixed the issue for me.
import sys
sys.argv=['']
del sys