我无法使argparse工作

Question

I want to add arguments through append in parser.add_argument but when I run it the following message appears

Prueba.py: error: argument -c1/--col1: expected one argument

Even when I tried to access help with -h it appears.

Here's the code

import argparse

parser = argparse.ArgumentParser(description='This is a program that makes a comparison between two files')

parser.add_argument('-c1', '--col1', action = 'append', default = [1,2], help = "Numbers in the first column")
parser.add_argument('-c2', '--col2', action = 'append', default = [1,2], help = "Numbers in the second column")

parser.add_argument('-f1', '--file1', type=str, action = 'store', help="File 1 Path")
parser.add_argument('-f2', '--file2', type=str, action = 'store', help="File 2 Path")


parser.parse_args('--col1'.split(','))
parser.parse_args('--col2'.split(','))

args = parser.parse_args()

col1 = args.col1
col2 = args.col2
file1 = args.file1
file2 = args.file2

print file1
print file2
print col1
print col2

Answer 1

Both --col1 and --col2 expect an associated argument. So, you are passing invalid arguments to parse_args .

On top of that, your use of split(',') is an error. Surely you meant to write split() . The error is benign as the code stands in the question. But as soon as you add extra arguments, it breaks down.

Replace the three calls to parse_args() to be this single call:

args = parser.parse_args('--col1 1 --col2 2'.split())

Here's a short demo program to demonstrate a working append argument.

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--arg', action='append')
print parser.parse_args('--arg foo --arg bar'.split())

Output

Namespace(arg=['foo', 'bar'])

Answer 2

It will work if you remove the lines

parser.parse_args('--col1'.split(','))
parser.parse_args('--col2'.split(','))

What are they supposed to do anyways? Why are you splitting fixed strings at ',' which are not even containing any ','?