Python small coup argparse library-summary of the usage of command line parameter parsing module

1. Import the module

• import argparse first imports the python library
• parser = argparse.ArgumentParser(description="your script desciption") creates a parsing object. The description parameter can be used to insert information describing the purpose of the script, and it can be empty.
• parser.add_argument() adds the command line parameters and options you want to use to the object
• parser.parse_args() for parsing

In projects where multiple files or different languages ​​are coordinated, python scripts often need to read parameters directly from the command line, then we need to apply the argparse library

2. Create a simple script

import argparse
parser = argparse.AugmentParser()
parser.parse_args()

3. Add parameter parser.add_argument()

positional arguments- positional parameters, mandatory by default

 parser.add_argument("b")

optional arguments

-w specified short parameter
--weight specified long parameter

 parser.add_argument("-w","--weight")

In this case, -v must specify the parameter value, otherwise an error will be reported. If you don't pass the parameter to -v and want to prevent the program from reporting an error, you can use:

 parser.add_argument("-w","--weight", action="store_true")

type-parameter type

<font color=black size =4>默认的为str

parser.add_argument("-w","--weight", type=int, action="store_true")

choices[]-optional values

Limit the parameter value range

parser.add_argument("-w","--weight", choices=[0, 1, 2, 3, 4], type=int, action="store_true")

default-parameter default value

parser.add_argument("-w","--weight", 
  									choices=[0, 1, 2, 3, 4], 
  									type=int,
  								    action="store_true",
  								    default=0)

Program usage help

description&&help

parser = argparse.ArgumentParser(description="训练DaliNet模型")
parser.add_argument("-w","--weight", 
  									choices=[0, 1, 2, 3, 4], 
  									type=int,
  								    action="store_true",
  								    default=0,
  								    help="存放weight的位置")
parser.parse_args()

parse_known_args() parsing

It is similar to parse_args(), but parse_known_args() will not report an error when accepting extra parameters from the command line

parser = argparse.ArgumentParser(description="训练DaliNet模型")
parser.add_argument("-w","--weight", 
  									choices=[0, 1, 2, 3, 4], 
  									type=int,
  								    action="store_true",
  								    default=0,
  								    help="存放weight的位置")
flags, unparsed = parser.parse_known_args() 
#$ python prog.py --flag_int 0.02 --double 0.03 a 1
#Namespace(flag_int=0.02)
#['--double', '0.03', 'a', '1']