检查是否设置了 argparse 可选参数 [英] Check if argparse optional argument is set or not

问题描述

我想检查用户是否设置了可选的 argparse 参数.

I would like to check whether an optional argparse argument has been set by the user or not.

我可以使用isset安全检查吗?

Can I safely check using isset?

像这样:

if(isset(args.myArg)):
    #do something
else:
    #do something else

这对 float/int/string 类型参数是否也一样?

Does this work the same for float / int / string type arguments?

我可以设置一个默认参数并检查它(例如，设置 myArg = -1，或为字符串设置"，或NOT_SET").但是，我最终要使用的值仅在脚本的后面计算.因此，我会将其设置为 -1 作为默认值，然后稍后将其更新为其他内容.与简单地检查值是否由用户设置相比，这似乎有点笨拙.

I could set a default parameter and check it (e.g., set myArg = -1, or "" for a string, or "NOT_SET"). However, the value I ultimately want to use is only calculated later in the script. So I would be setting it to -1 as a default, and then updating it to something else later. This seems a little clumsy in comparison with simply checking if the value was set by the user.

推荐答案

我认为可选参数(用 -- 指定)被初始化为 None 如果它们不是提供.所以你可以用 is not None 来测试.试试下面的例子:

I think that optional arguments (specified with --) are initialized to None if they are not supplied. So you can test with is not None. Try the example below:

import argparse

def main():
    parser = argparse.ArgumentParser(description="My Script")
    parser.add_argument("--myArg")
    args, leftovers = parser.parse_known_args()

    if args.myArg is not None:
        print "myArg has been set (value is %s)" % args.myArg

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