问题：不带参数的Python argparse命令行标志
如何在命令行参数中添加可选标志？
例如。所以我可以写
python myprog.py
要么
python myprog.py -w
我试过了
parser.add_argument('-w')
但是我收到一条错误消息说
Usage [-w W]
error: argument -w: expected one argument
我认为这意味着它需要-w选项的参数值。接受旗帜的方式是什么？
我在这个问题上发现http://docs.python.org/library/argparse.html相当不透明。
How do I add an optional flag to my command line args?
eg. so I can write
python myprog.py
or
python myprog.py -w
I tried
parser.add_argument('-w')
But I just get an error message saying
Usage [-w W]
error: argument -w: expected one argument
which I take it means that it wants an argument value for the -w option. What’s the way of just accepting a flag?
I’m finding http://docs.python.org/library/argparse.html rather opaque on this question.
回答 0
如您所愿，参数w在命令行中的-w之后需要一个值。如果您只是想通过设置变量True或来翻转开关False，请访问http://docs.python.org/dev/library/argparse.html#action（特别是store_true和store_false）
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-w', action='store_true')
其中action='store_true'暗示default=False。
相反，您可能有action='store_false'，这意味着default=True。
As you have it, the argument w is expecting a value after -w on the command line. If you are just looking to flip a switch by setting a variable True or False, have a look at http://docs.python.org/dev/library/argparse.html#action (specifically store_true and store_false)
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-w', action='store_true')
where action='store_true' implies default=False.
Conversely, you could haveaction='store_false', which implies default=True.
回答 1
添加一个快速片段以使其可以执行：
资料来源：myparser.py
import argparse
parser = argparse.ArgumentParser(description="Flip a switch by setting a flag")
parser.add_argument('-w', action='store_true')
args = parser.parse_args()
print args.w
用法：
python myparser.py -w
>> True
Adding a quick snippet to have it ready to execute:
Source: myparser.py
import argparse
parser = argparse.ArgumentParser(description="Flip a switch by setting a flag")
parser.add_argument('-w', action='store_true')
args = parser.parse_args()
print args.w
Usage:
python myparser.py -w
>> True
回答 2
这是一种快速的方法，sys尽管功能有限，但除了.. 之外不需要任何其他功能：
flag = "--flag" in sys.argv[1:]
[1:] 如果完整的文件名是 --flag
Here’s a quick way to do it, won’t require anything besides sys.. though functionality is limited:
flag = "--flag" in sys.argv[1:]
[1:] is in case if the full file name is --flag
