指定输入参数的格式 argparse python
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/25470844/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Specify format for input arguments argparse python
提问by Sohaib
I have a python script that requires some command line inputs and I am using argparse for parsing them. I found the documentation a bit confusing and couldn't find a way to check for a format in the input parameters. What I mean by checking format is explained with this example script:
我有一个需要一些命令行输入的 python 脚本，我正在使用 argparse 来解析它们。我发现文档有点混乱，找不到检查输入参数格式的方法。这个示例脚本解释了我所说的检查格式的意思：
parser.add_argument('-s', "--startdate", help="The Start Date - format YYYY-MM-DD ", required=True)
parser.add_argument('-e', "--enddate", help="The End Date format YYYY-MM-DD (Inclusive)", required=True)
parser.add_argument('-a', "--accountid", type=int, help='Account ID for the account for which data is required (Default: 570)')
parser.add_argument('-o', "--outputpath", help='Directory where output needs to be stored (Default: ' + os.path.dirname(os.path.abspath(__file__)))
I need to check for option -sand -ethat the input by the user is in the format YYYY-MM-DD. Is there an option in argparse that I do not know of which accomplishes this.
我需要检查选项-s以及-e用户输入的格式是否为YYYY-MM-DD. argparse 中是否有我不知道的选项可以实现这一点。
采纳答案by jonrsharpe
Per the documentation:
根据文档：
The
typekeyword argument ofadd_argument()allows any necessary type-checking and type conversions to be performed ...type=can take any callable that takes a single string argument and returns the converted value
所述
type的关键字参数add_argument()允许执行任何必要的类型检查和类型转换...type=可以采取任何可调用采用单个字符串参数，并返回转换后的值
You could do something like:
你可以这样做：
def valid_date(s):
try:
return datetime.strptime(s, "%Y-%m-%d")
except ValueError:
msg = "Not a valid date: '{0}'.".format(s)
raise argparse.ArgumentTypeError(msg)
Then use that as type:
然后将其用作type：
parser.add_argument("-s",
"--startdate",
help="The Start Date - format YYYY-MM-DD",
required=True,
type=valid_date)
回答by Evan V
Just to add on to the answer above, you can use a lambda function if you want to keep it to a one-liner. For example:
只是为了补充上面的答案，如果您想将其保持为单行，您可以使用 lambda 函数。例如：
parser.add_argument('--date', type=lambda d: datetime.strptime(d, '%Y%m%d'))
Old thread but the question was still relevant for me at least!
旧线程，但这个问题至少对我来说仍然相关！
回答by Micha? Górny
For others who hit this via search engines: in Python 3.7, you can use the standard .fromisoformatclass method instead of reinventing the wheel for ISO-8601 compliant dates, e.g.:
对于通过搜索引擎点击此内容的其他人：在 Python 3.7 中，您可以使用标准.fromisoformat类方法而不是为符合 ISO-8601 的日期重新发明轮子，例如：
parser.add_argument('-s', "--startdate",
help="The Start Date - format YYYY-MM-DD",
required=True,
type=datetime.date.fromisoformat)
parser.add_argument('-e', "--enddate",
help="The End Date format YYYY-MM-DD (Inclusive)",
required=True,
type=datetime.date.fromisoformat)
