I have some python script foo.py with many arguments. Inside that script I am using argparse import ArgumentParser to parse them.
I want to pass an array as the value of one of them from bash. I have tried:
python foo.py --arg1=1 --arrArg=[1,2] --arg3=x
when I print them inside the script I get:
arg1=1
arrArg=['1',',','2']
arg3=x
How do I pass the arry as numbers from bash?
If you use the script yourself, and only yourself, then you can use eval(). But watch out, this is not a very safe function. Don't ever use this when you don't know what the input is.
import argparse
parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('--arr',
help='Array of integers')
args = parser.parse_args()
data = eval(args.arr)
print(type(data))
print(data)
Otherwise, use the nargs='+' argument for argparse:
import argparse
parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('--arr', nargs='+', type=int,
help='Array of integers')
args = parser.parse_args()
data = args.arr
print(type(data))
print(data)
And call your script with python foo.py --arr 1 2 3 --bla blablabla
nargs=n, where n is my array length but only thanks to your answer.There are few ways you can do this: using nargs or using action=append:
import argparse
parser = argparse.ArgumentParser()
# You can specify number of elements in an array.
# '+' == 1 or more.
# '*' == 0 or more.
# '?' == 0 or 1.
# An int is an explicit number of elements to accept.
parser.add_argument('--nargs', nargs='+')
# To make the input integers
parser.add_argument('--nargs-int-type', nargs='+', type=int)
# Using `action=append`. But out must provide the flag for every
# input. And you can use type=int here as well.
parser.add_argument('--append-action', action='append')
# To show the results
for _, value in parser.parse_args()._get_kwargs():
if value is not None:
print(value)
And the results will look like this:
$ python arg.py --nargs 1234 2345 3456 4567
['1234', '2345', '3456', '4567']
$ python arg.py --nargs-int-type 1234 2345 3456 4567
[1234, 2345, 3456, 4567]
$ # Negative numbers are also handled
$ python arg.py --nargs-int-type -1234 2345 -3456 4567
[-1234, 2345, -3456, 4567]
$ python arg.py --append-action 1234 --append-action 2345 --append-action 3456 --append-action 4567
['1234', '2345', '3456', '4567']
Reference: https://docs.python.org/3/library/argparse.html#nargs
