argparse python模块的文档虽然非常棒,但对于我这个初学者来说,现在还难以理解。我不需要在命令行上做数学运算,也不需要在屏幕上修改格式行或更改选项字符。我想做的就是“如果arg是A,做这个,如果B做那个,如果以上都没有显示帮助并退出”。


当前回答

这是一个新手,但是将Python与Powershell结合起来并使用这个模板,灵感来自深入而伟大的Python命令行参数-真正的Python

在init_argparse()中可以做很多事情,这里我只介绍最简单的场景。

import argparse use if __name__ == "__main__": main() pattern to execute from terminal parse arguments within the main() function that has no parameters as all define a init_argparse() function create a parser object by calling argparse.ArgumentParser() declare one or more argumnent with parser.add_argument("--<long_param_name>") return parser parse args by creating an args object by calling parser.parse_args() define a function proper with param1, param2, ... call function_proper with params being assigned as attributes of an args object e.g. function_proper(param1=args.param1, param2=args.param2) within a shell call the module with named arguments: e.g. python foobar.py --param1="foo" --param2=="bar"

#file: foobar.py
import argparse

def function_proper(param1, param2):
    #CODE...

def init_argparse() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser()
    parser.add_argument("--param1")
    parser.add_argument("--param2")
    return parser


def main() -> None:
    parser = init_argparse()
    args = parser.parse_args()
    function_proper(param1=args.param1, param2=args.param2)


if __name__ == "__main__":
    main()
>>> python .\foobar.py --param1="foo" --param2=="bar"

其他回答

也可以使用plac (argparse的包装器)。

作为奖励,它生成整洁的帮助说明-见下文。

示例脚本:

#!/usr/bin/env python3
def main(
    arg: ('Argument with two possible values', 'positional', None, None, ['A', 'B'])
):
    """General help for application"""
    if arg == 'A':
        print("Argument has value A")
    elif arg == 'B':
        print("Argument has value B")

if __name__ == '__main__':
    import plac
    plac.call(main)

示例输出:

没有提供参数- example.py:

usage: example.py [-h] {A,B}
example.py: error: the following arguments are required: arg

提供了意外的参数- example.py

usage: example.py [-h] {A,B}
example.py: error: argument arg: invalid choice: 'C' (choose from 'A', 'B')

提供正确的参数- example.py

Argument has value A

完整帮助菜单(自动生成)- example.py -h:

usage: example.py [-h] {A,B}

General help for application

positional arguments:
  {A,B}       Argument with two possible values

optional arguments:
  -h, --help  show this help message and exit

简短说明:

实参的名称通常等于形参名称(arg)。

arg参数后的元组注释的含义如下:

描述(有两个可能值的参数) 参数类型- 'flag', 'option'或'positional' (positional)之一 缩写(无) 参数值的类型-例如。float, string (None) 限制选项集(['A', 'B'])

文档:

要了解更多关于使用placa的知识,请查看它的伟大文档:

Plac:解析命令行的简单方法

使用argparse和修改'-h'/ '——help'开关来显示你自己的个人代码帮助指令的一个非常简单的方法是将默认帮助设置为False,你也可以添加尽可能多的额外的.add_arguments:

import argparse

parser = argparse.ArgumentParser(add_help=False)

parser.add_argument('-h', '--help', action='help',
                help='To run this script please provide two arguments')
parser.parse_args()

执行命令python test.py -h

输出:

usage: test.py [-h]

optional arguments:
  -h, --help  To run this script please provide two arguments

这是一个新手,但是将Python与Powershell结合起来并使用这个模板,灵感来自深入而伟大的Python命令行参数-真正的Python

在init_argparse()中可以做很多事情,这里我只介绍最简单的场景。

import argparse use if __name__ == "__main__": main() pattern to execute from terminal parse arguments within the main() function that has no parameters as all define a init_argparse() function create a parser object by calling argparse.ArgumentParser() declare one or more argumnent with parser.add_argument("--<long_param_name>") return parser parse args by creating an args object by calling parser.parse_args() define a function proper with param1, param2, ... call function_proper with params being assigned as attributes of an args object e.g. function_proper(param1=args.param1, param2=args.param2) within a shell call the module with named arguments: e.g. python foobar.py --param1="foo" --param2=="bar"

#file: foobar.py
import argparse

def function_proper(param1, param2):
    #CODE...

def init_argparse() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser()
    parser.add_argument("--param1")
    parser.add_argument("--param2")
    return parser


def main() -> None:
    parser = init_argparse()
    args = parser.parse_args()
    function_proper(param1=args.param1, param2=args.param2)


if __name__ == "__main__":
    main()
>>> python .\foobar.py --param1="foo" --param2=="bar"

注意Python HOWTOs中的Argparse教程。它从最基本的例子开始,比如这个:

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("square", type=int,
                    help="display a square of a given number")
args = parser.parse_args()
print(args.square**2)

然后发展到不那么基本的。

这里有一个预定义选项的例子,就像问的那样:

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("square", type=int,
                    help="display a square of a given number")
parser.add_argument("-v", "--verbosity", type=int, choices=[0, 1, 2],
                    help="increase output verbosity")
args = parser.parse_args()
answer = args.square**2
if args.verbosity == 2:
    print("the square of {} equals {}".format(args.square, answer))
elif args.verbosity == 1:
    print("{}^2 == {}".format(args.square, answer))
else:
    print(answer)

这是另一个总结介绍,受这篇文章的启发。

import argparse

# define functions, classes, etc.

# executes when your script is called from the command-line
if __name__ == "__main__":

    parser = argparse.ArgumentParser()
    #
    # define each option with: parser.add_argument
    #
    args = parser.parse_args() # automatically looks at sys.argv
    #
    # access results with: args.argumentName
    #

参数由以下组合定义:

parser.add_argument( 'name', options... )              # positional argument
parser.add_argument( '-x', options... )                # single-char flag
parser.add_argument( '-x', '--long-name', options... ) # flag with long name

常见的选项有:

help: description for this arg when --help is used. default: default value if the arg is omitted. type: if you expect a float or int (otherwise is str). dest: give a different name to a flag (e.g. '-x', '--long-name', dest='longName'). Note: by default --long-name is accessed with args.long_name action: for special handling of certain arguments store_true, store_false: for boolean args '--foo', action='store_true' => args.foo == True store_const: to be used with option const '--foo', action='store_const', const=42 => args.foo == 42 count: for repeated options, as in ./myscript.py -vv '-v', action='count' => args.v == 2 append: for repeated options, as in ./myscript.py --foo 1 --foo 2 '--foo', action='append' => args.foo == ['1', '2'] required: if a flag is required, or a positional argument is not. nargs: for a flag to capture N args ./myscript.py --foo a b => args.foo = ['a', 'b'] choices: to restrict possible inputs (specify as list of strings, or ints if type=int).