specifying a list of list as a command line argument in python 3

Question

I think the question is self explanatory. I would like to use a list of list as a command line argument like so:

python3 awesome_code.py --list=[[var1,var2],[var3,v4]..]

Is this possible at all?

It's certainly possible, but you'll have to do careful quoting to get expressions with [ ] through your average shell. — Roland Weber
– Roland Weber, Commented Jun 4, 2019 at 20:28
It's not exactly possible. Command-line arguments are strings only. You can pass a string that looks like a list, but you'll have to parse it to get a python list out of it. — Blorgbeard
– Blorgbeard, Commented Jun 4, 2019 at 20:36
argparse might be of help, check out similar question here — jean
– jean, Commented Jun 4, 2019 at 20:50

wjandrea · Accepted Answer · 2019-09-01 20:50:59Z

1

You can use json.loads for this.

import json
import sys
l = json.loads(sys.argv[1])
for x in l:
    print(x)

python3 test.py [[1,2,3],[4,5,6]]

Output:

[1, 2, 3]
[4, 5, 6]

edited Sep 1, 2019 at 20:50

wjandrea

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answered Sep 1, 2019 at 20:30

Ankit

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wjandrea · Accepted Answer · 2019-09-01 21:06:04Z

0

You could use argparse to define a more typical shell command line like this:

python3 awesome_code.py --list v1 v2 --list v3 v4

Where the result would be

[['v1', 'v2'], ['v3', 'v4']]

Here is the example code:

import argparse
parser = argparse.ArgumentParser()
parser.add_argument(
    '--list',
    action='append',
    nargs='*',
    )
args = parser.parse_args('--list v1 v2 --list v3 v4'.split())
print(args.list)

edited Sep 1, 2019 at 21:06

answered Sep 1, 2019 at 21:01

wjandrea

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