Passing values from command line python

Question

I have a python function that requires several parameters. Something like:

def func(par1=1, par2=2, par3=3):
...

I want to make this callable from command line such as: function.py par1=1 par2=2 par3=3.

I was thinking of doing it something like this:

import sys

if sys.argv[0][0:4]=="par1":
   par1=int(sys.argv[0][5:])
else:
   par1=1

but it doesn't look very nice, as the user might pass just some parametrs, or they might pass it as par1 =1 or par1= 1 or par1 = 1 so I would have to hard code with if-else all these possibilities. Is there a nicer, more professional solution? Thank you!

function.py par1=1 par2=2 par3=3 violates expectations on UNIX commands. function.py --par1=1 --par2=2 --par3=3 looks much better. Consult argparse documentation. — Amadan
– Amadan, Commented Nov 21, 2019 at 5:35
Possible duplicate of What's the best way to parse command line arguments? — AMC
– AMC, Commented Nov 21, 2019 at 5:48

ted · Accepted Answer · 2019-11-21 05:35:26Z

3

Use argparse from the standard library

import argparse

parser = argparse.ArgumentParser()
parser.add_argument("--par1", type=int, default=1, help="This is the description")
opts = parser.parse_args()

print(opts.part1)

checkout the docs for more details: https://docs.python.org/3/library/argparse.html

answered Nov 21, 2019 at 5:35

ted

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FiddleStix · Accepted Answer · 2022-03-14 14:56:32Z

0

As mentioned in Amadan's comment, you probably want function.py --par1=1 --par2=2 --par3=3 and not function.py par1=1 par2=2 par3=3

For the former, you can use

function.py

import argparse

parser = argparse.ArgumentParser()
parser.add_argument("--par1", default=11)
parser.add_argument("--par2", default=22)
parser.add_argument("--par3", default=33)
parser.add_argument("--par4", default=44)
opts = parser.parse_args()

print(opts.par1, opts.par2, opts.par3, opts.par4)

$ python function.py  # default values
11 22 33 44

$ python function.py --par1 99  # spaces are OK
99 22 33 44

$ python function.py --par1=99  # = are OK
99 22 33 44

answered Mar 14, 2022 at 14:56

FiddleStix

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