The Argparse in Python

Argparse is a standard module used by Python to parse command-line arguments and options in place of obsolete optparse modules. The role of the Argparse module is used to parse command-line arguments.

The most basic, starting from one of the simplest programs:

Import= argparse. Argumentparser ()

Operation Result:

　

Positioning parameters:

Import argparseparser=argparse. Argumentparser () parser.add_argument ("echo") parser.add_argument ("  Hello"= Parser.parse_args ()print Args.ehco

Run:

11echo  Hello11echo1  echo  Hello11echo   Hello  Echo

Method add_argument() To specify the command parameters that the program needs to accept;

And Argparse is the default string, if entered as a numeric error, as shown in the following code:

1 Import Argparse 2 parser=argparse. Argumentparser ()3 parser.add_argument ("echo", help="  echo the string,"here")4 args=Parser.parse_args ()5  Print args.echo*10

Run:

1 4  last):  '1.py'5 in <module>     Print args.square** 2for'str' ' int '

The code must be added type= the type you need (like this requires an int type):

1 Import Argparse 2 parser=argparse. Argumentparser ()3 parser.add_argument ("echo", help="Echo The string "Here", type=int)4 args=Parser.parse_args ()  5Print args.echo*10

--help:

Although the help information is now very beautiful, but not good enough. For example, we know that ECHO is a positional parameter, but we don't know the meaning of the parameter, only by guessing or reading the source code. Below, we can make it more helpful:

1 Import Argparse 2 parser = Argparse. Argumentparser ()3 parser.add_argument ("echo", help="Echo The string you use there")4 args = Parser.parser_args ()5 Print Args.echo

Run:

1 $ python 1.py-h2 usage:1.py [-h] Echo34positional Arguments:5  echo        echo the stringyou use here67Optional Arguments:8   -H,--help and   exit

Reference type:

In general, if you do not specify a parameter type, Argparse defaults to the string type, which can be specified by type;

1 Import Argparse 2 parser = Argparse. Argumentparser ()3 parser.add_argument ("square", help="  Display a square of a givennumber", type=int)4 args = Parser.parse_args () 
    5print args.square**2

You can also use DEFAULT=XX to specify values for default parameters, such as:

1 parser.add_argument ("echo", action="count", default=0)

Optional Parameters:

1 ImportArgparse2Parser =Argparse. Argumentparser ()3Parser.add_argument ("--verbosity", help="Increase output verbosity")4args =Parser.parse_args ()5 ifargs.verbosity:6     Print "verbosity turned on"

Run:

1 1  11. PY--helpusage:prog.py [-h] [--verbosity verbosity]

There is also a shorthand for optional parameters:

1 ImportArgparse2Parser =Argparse. Argumentparser ()3Parser.add_argument ("-vwww","--verbose", help="Increase output verbosity", action="store_true")4args =Parser.parse_args ()5 ifArgs.verbose:6     Print "verbosity turned on"

Here the-VWW is its shorthand, Action:store_true/store_false: boolean switch. Store_true. The default is false, and the input is true. Store_flase opposite;

1 $ python prog.py-v2verbosity turnedon3 $ python prog.py – Help 4 usage:prog.py [-h] [-v]56Optional arguments:7   -H, --help show this help     message and exit8   -V,--verbose  increase output verbosity

In the command line as long as the-vwww before the same line, if the-VP will be error, if it is-VW, the default is-vwww, also a 23 is correct;

Attention:

1 parser.add_argument ("-v""--verbose", action= " store_true ", help="increase output verbosity")

These are not sequential, of course, it can be the same as above;

Parameter conflict:

So far, we've used [argparse.ArgumentParser][6] two methods to look at one of his other methods add_mutually_exclusive_group() . It allows us to specify a parameter and other parameter conflicts. The following procedure modifies the following program to learn more about this new method: We will add the parameter --quiet , it conflicts with the parameter --verbose , cannot specify simultaneously:

1 ImportArgparse2Parser =Argparse. Argumentparser ()3Parser.add_argument ("- v","--verbose", Type=int, help="The base")4Parser.add_argument ("- Q","--quiet", Type=int, help="The exponent")5 6args =Parser.parse_args ()7 ifArgs.quiet:8     Print "111111"9 elifArgs.verbose:Ten     Print "222222"

Run:

1 1. py-v-Q2 $11111

Another methodadd_mutually_exclusive_group():

1 ImportArgparse2 3Parser =Argparse. Argumentparser ()4Group =Parser.add_mutually_exclusive_group ()5Group.add_argument ("- v","--verbose", action="store_true")6Group.add_argument ("- Q","--quiet", action="store_true")
7 if args.quiet:

8 Print "111111"

9 elif args.verbose:

 Print "222222"             

Run:

1 1. py-v-Q21. py [-h] [-v |-Q]3 test.py:error:argument-q/-- Quiet:not allowed with Argument-v/--verbose

Indicates that it can be used -v or -q , but not used at the same time.

The Argparse in Python