I want to pass a list of names into my program written in Python from console. For instance, I would like to use a way similar to this (I know it shouldn't work because of bash):
$ python myprog.py -n name1 name2 So, I tried this code:
# myprog.py from argparse import ArgumentParser parser = ArgumentParser() parser.add_argument('-n', '--names-list', default=[]) args = parser.parse_args() print(args.names_list) # I need ['name1', 'name2'] here That led to the error:
usage: myprog.py [-h] [-n NAMES_LIST] myprog.py: error: unrecognized arguments: name2 I know I could pass the names with quotes "name1 name2" and split it in my code args.names_list.split(). But I'm curious, is there a better way to pass the list of strings via argparse module.
Any ideas would be appreciated.
Thanks!
3 Answers
You need to define --names-list to take an arbitrary number of arguments.
parser.add_argument('-n', '--names-list', nargs='+', default=[]) Note that options with arbitrary number of arguments don't typically play well with positional arguments, though:
# Is this 4 arguments to -n, or # 3 arguments and a single positional argument, or ... myprog.py -n a b c d You need to use nargs:
parser.add_argument('-n', '--names-list', nargs="*") parser.add_argument('-n', '--names-list', default=[], nargs='+') 
