Python argparse: name parameters
Question:
I’m writing a program that use argparse, for parsing some arguments that I need.
for now I have this:
parser.add_argument('--rename', type=str, nargs=2, help='some help')
when I run this script I see this:
optional arguments:
-h, --help show this help message and exit
--rename RENAME RENAME
some help
How can I change my code in that way that the help “page” will show me:
--rename OLDFILE NEWFILE
Can I then use OLDFILE and NEWFILE value in this way?
args.rename.oldfile
args.rename.newfile
Answers:
If you set metavar=('OLDFILE', 'NEWFILE')
:
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--rename', type=str, nargs=2, help='some help',
metavar=('OLDFILE', 'NEWFILE'))
args = parser.parse_args()
print(args)
Then test.py -h
yields
usage: test.py [-h] [--rename OLDFILE NEWFILE]
optional arguments:
-h, --help show this help message and exit
--rename OLDFILE NEWFILE
some help
You can then access the arguments with
oldfile, newfile = args.rename
If you really want to access the oldfile with args.rename.oldfile
you could set up a custom action:
import argparse
class RenameAction(argparse.Action):
def __call__(self, parser, namespace, values, option_string=None):
setattr(namespace, self.dest,
argparse.Namespace(
**dict(zip(('oldfile', 'newfile'),
values))))
parser = argparse.ArgumentParser()
parser.add_argument('--rename', type=str, nargs=2, help='some help',
metavar=('OLDFILE', 'NEWFILE'),
action=RenameAction)
args = parser.parse_args()
print(args.rename.oldfile)
but it extra code does not really seem worth it to me.
Read the argparse documentation (http://docs.python.org/2.7/library/argparse.html#metavar):
Different values of nargs may cause the metavar to be used multiple times. Providing a tuple to metavar specifies a different display for each of the arguments:
>>> parser = argparse.ArgumentParser(prog='PROG')
>>> parser.add_argument('-x', nargs=2)
>>> parser.add_argument('--foo', nargs=2, metavar=('bar', 'baz'))
>>> parser.print_help()
usage: PROG [-h] [-x X X] [--foo bar baz]
optional arguments:
-h, --help show this help message and exit
-x X X
--foo bar baz
I’m writing a program that use argparse, for parsing some arguments that I need.
for now I have this:
parser.add_argument('--rename', type=str, nargs=2, help='some help')
when I run this script I see this:
optional arguments:
-h, --help show this help message and exit
--rename RENAME RENAME
some help
How can I change my code in that way that the help “page” will show me:
--rename OLDFILE NEWFILE
Can I then use OLDFILE and NEWFILE value in this way?
args.rename.oldfile
args.rename.newfile
If you set metavar=('OLDFILE', 'NEWFILE')
:
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--rename', type=str, nargs=2, help='some help',
metavar=('OLDFILE', 'NEWFILE'))
args = parser.parse_args()
print(args)
Then test.py -h
yields
usage: test.py [-h] [--rename OLDFILE NEWFILE]
optional arguments:
-h, --help show this help message and exit
--rename OLDFILE NEWFILE
some help
You can then access the arguments with
oldfile, newfile = args.rename
If you really want to access the oldfile with args.rename.oldfile
you could set up a custom action:
import argparse
class RenameAction(argparse.Action):
def __call__(self, parser, namespace, values, option_string=None):
setattr(namespace, self.dest,
argparse.Namespace(
**dict(zip(('oldfile', 'newfile'),
values))))
parser = argparse.ArgumentParser()
parser.add_argument('--rename', type=str, nargs=2, help='some help',
metavar=('OLDFILE', 'NEWFILE'),
action=RenameAction)
args = parser.parse_args()
print(args.rename.oldfile)
but it extra code does not really seem worth it to me.
Read the argparse documentation (http://docs.python.org/2.7/library/argparse.html#metavar):
Different values of nargs may cause the metavar to be used multiple times. Providing a tuple to metavar specifies a different display for each of the arguments:
>>> parser = argparse.ArgumentParser(prog='PROG')
>>> parser.add_argument('-x', nargs=2)
>>> parser.add_argument('--foo', nargs=2, metavar=('bar', 'baz'))
>>> parser.print_help()
usage: PROG [-h] [-x X X] [--foo bar baz]
optional arguments:
-h, --help show this help message and exit
-x X X
--foo bar baz