Entry

Reducing redundant answers (was: strings in lists)

Jul 5th, 2000 09:59
Nathan Wallace, Hans Nowak, Snippet 75, Tim Peters

"""
Packages: miscellaneous.fun
"""
"""
[Christian Tismer]
> Congrats to us all, who answered in parallel.
>
> Five correct answers to one simple question,
> and none much worse than the others.
>
> Is there a way to save some redundancy in the future?:-)
Certainly!  When you're deciding whether to reply, simply look at your
watch and reply if and only if it's between 0 and 11 seconds (inclusive)
after the minute.
Hmm.  That's rather old-fashioned, isn't it?  OK, I'll attach ohdear.py.
that-guido-thought-of-everything-ly y'rs  - tim
"""
numwizards = 5
__doc__ = """Decide whether to reply to a simple c.l.py question.
Usage:
    ohdear [numwizards]
where numwizards is an optional integer > 0, defaulting to %d, estimating
the number of currently active c.l.py wizards who are also wondering
whether to answer, and who-- also like you --believe a technological
approach has got to be the right thing to do no matter how stupid it is.
""" % (numwizards,)
import sys
import random
import bisect
class EightBall:
    def __init__(self, answers, weights):
        """weights, answers -> an instance x of EightBall.
        x.choose() returns answers[i] with relative frequency
        weights[i]/sum(weights).  answers and weights must have
        the same number of elements, > 0.
        """
        n = len(answers)
        if n == 0:
            raise ValueError("answers must not be empty")
        if n != len(weights):
            raise ValueError("must have same # of answers as weights")
        sum = 0.0
        for w in weights:
            if not w >= 0:
                raise ValueError("weights must be non-negative; " + `w`)
            sum = sum + w
        if sum == 0:
            raise ValueError("must have at least one non-zero weight")
        partial = 0.0
        cumulative = []
        for w in weights:
            partial = partial + w
            cumulative.append(partial / sum)
        self.answers = answers
        self.cumulative = cumulative
    def choose(self):
        i = bisect.bisect(self.cumulative, random.random())
        return self.answers[i]
def _main():
    global numwizards
    realwizard = 1   # generosity is the true Python spirit
    if len(sys.argv) > 2:
        realwizard = 0
    elif len(sys.argv) == 2:
        try:
            numwizards = int(sys.argv[1])
            realwizard = numwizards > 0
        except:
            realwizard = 0
    if not realwizard:
        sys.stderr.write("No, you're not qualified to answer anything.\n")
        sys.exit(1)
    chooser = EightBall(
        ["No, chances are someone else will.  Don't be a pest.",
         "Yes, chances are nobody else will.  Be a hero."],
        [numwizards - 1, 1])
    print chooser.choose()
if __name__ == "__main__":
    random.seed()    # seed via current time
    _main()