python 的 Optparse

Question

我是 python 的 optparse 的新手并尝试了以下操作：

def plot():
    x=[1,2,3]
    y=[4,5,6]
    plt.plot(x,y)
    plt.savefig('trial.pdf')

parser=OptionParser()
parser.add_option("-p", "--plot", action="callback", callback=plot)
(options, args)=parser.parse_args()

我在终端输入 python3 parse.py -p，它给出了：

Traceback (most recent call last):
  File "firstparse.py", line 15, in <module>
    (options, args)=parser.parse_args()
  File "/usr/lib/python3.5/optparse.py", line 1386, in parse_args
    stop = self._process_args(largs, rargs, values)
  File "/usr/lib/python3.5/optparse.py", line 1430, in _process_args
    self._process_short_opts(rargs, values)
  File "/usr/lib/python3.5/optparse.py", line 1535, in _process_short_opts
    option.process(opt, value, values, self)
  File "/usr/lib/python3.5/optparse.py", line 784, in process
    self.action, self.dest, opt, value, values, parser)
  File "/usr/lib/python3.5/optparse.py", line 804, in take_action
    self.callback(self, opt, value, parser, *args, **kwargs)
TypeError: plot() takes 0 positional arguments but 4 were given

我不太了解位置参数错误。谁能告诉我哪里错了？

Answer 1

查看 documentation:

当使用 callback 时，您提供了一个用于处理传入参数的函数，该函数使用四个参数调用：option, opt_str, value, parser

option

is the Option instance that’s calling the callback

opt_str

is the option string seen on the command-line that’s triggering the callback...

value

is the argument to this option seen on the command-line...

parser

is the OptionParser instance driving the whole thing, mainly useful because you can access some other interesting data through its instance attributes...

本质上，您是在尝试通过 plot 函数将命令行中的参数处理成它的值。

我怀疑您正在尝试从命令行选择操作（例如 plot）到运行，所以可能更像是：

parser=ArgumentParser()
parser.add_argument("-p", "--plot", action="store_true")
args = parser.parse_args()
if args.plot is True:
    plot()

注意：optparse 自 3.2 以来已被弃用，您现在应该使用 argparse。

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