检查是否设置了argparse可选参数

本文介绍了检查是否设置了argparse可选参数的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 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.

我可以安全地使用isset检查吗?

Can I safely check using isset?

类似这样的东西:

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

对于float/int/string类型参数，这是否相同?

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，或为字符串或" NOT_SET).但是，我最终要使用的值仅在脚本的稍后部分中计算.因此，我会将其默认设置为-1，然后稍后将其更新为其他内容.与仅检查该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，如果未提供可选参数(用--指定)，则会将其初始化为None.因此，您可以使用is not None进行测试.请尝试以下示例:

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 as ap def main(): parser = ap.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