Argparser returns “--mode=client --port=52085” and crashes

问题

Whenever I use parser.parse_args(), the kernel crashes. For instance:

import argparse
import numpy as np

parser = argparse.ArgumentParser()
parser.add_argument("--return_counts", type=bool, default=True)

opt = parser.parse_args()

arr = np.random.randint(0, 10, 100)

It gives this error:

usage: pydevconsole.py [-h] [--return_counts RETURN_COUNTS]
pydevconsole.py: error: unrecognized arguments: --mode=client --port=52085

But, if I use parser.parse_known_args(), it works.

import argparse
import numpy as np

parser = argparse.ArgumentParser()
parser.add_argument("--return_counts", type=bool, default=True)

opt, unknown = parser.parse_known_args()

arr = np.random.randint(0, 10, 100)

It works, and opt gives this:

print(opt)
Out[3]: Namespace(return_counts=True)

And unknown gives this:

Out[4]: ['--mode=client', '--port=52162']

Can someone explain the sorcery behind this?

回答1:

It seems like you aren't providing the correct arguments to your command line. You need to add more arguments to the parser.

import argparse
import numpy as np

parser = argparse.ArgumentParser()
parser.add_argument("--return_counts", type=bool, default=True)
parser.add_argument("--mode", default='client')
parser.add_argument("--port", default=52162)

args = parser.parse_args()

Now you can use python3 pydevconsole.py --return_counts True --mode client --port 52162 in the command line and you will see:

print(args.return_counts) # True
print(args.mode) # client
print(args.port) # 52162

回答2:

parse_args and parse_known_args use sys.argv unless you pass an argument to them (for instance parser.parse_args(['a', 'b', 'c']))

whatever thing you started (presumably ipython / jupyter / etc.) was started with --mode=client --port=52162

The reason parse_known_args doesn't produce an error and exit is because it only parses the known arguments -- and not producing an error for unknown arguments (it can still produce errors for known arguments, for instance if they're the wrong type)

来源：https://stackoverflow.com/questions/59081228/argparser-returns-mode-client-port-52085-and-crashes

标签

python

argparse