generated from mwc/lab_server
98 lines
4.3 KiB
Python
98 lines
4.3 KiB
Python
from banjo.models import Model, StringField, IntegerField
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from fuzzywuzzy import fuzz
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class Riddle(Model):
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question = StringField()
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answer = StringField()
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guesses = IntegerField()
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correct = IntegerField()
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MIN_FUZZ_RATIO = 80
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def __repr__(self):
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"""Declares how to represent a Riddle as a string.
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A riddle's string will look something like this:
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<Riddle 12: Where can you get dragon milk? (3/15)>
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"""
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return "<Riddle {}: {} ({}/{})>".format(
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self.id or '(unsaved)',
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self.question,
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self.correct,
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self.guesses
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)
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def is_valid(self):
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"Checks whether this riddle is valid. In other words, when validate() finds no errors."
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return len(self.validate()) == 0
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def validate(self):
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"Checks whether this riddle can be saved"
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errors = []
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if self.question is None:
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errors.append("question is required")
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if self.answer is None:
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errors.append("answer is required")
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return errors
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def difficulty(self):
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"""Calculates and returns the riddle's difficulty.
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The difficulty is basically 1 minus the fraction of guesses which were correct.
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So a Riddle with a difficulty of 1 is impossibly hard, while a Riddle with a difficulty
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of 0 is easy--everyone gets it right!
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There is an interesting detail here though. Instead of 1 - correct/guesses, we add 1 to
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correct and we add 1 to guesses. This is called "smoothing" and it provides two benefits:
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First, we avoid having an undefined difficulty when there have been no guesses (0/0 would
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raise a ZeroDivisionError) Second, it gives better values for difficulty when there have been no
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correct guesses or no incorrect guesses. Consider an impossible riddle:
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Number of wrong guesses Difficulty with smoothing Difficulty without smoothing
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0 0 error
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1 0.5 1
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2 0.66 1
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3 0.75 1
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4 0.8 1
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100 0.99 1
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1000 0.999 1
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With smoothing, a Riddle's difficulty can only be really high if there are few correct guesses
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and a lot of guesses. This seems like the right way to define difficulty.
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"""
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return 1 - (self.correct + 1) / (self.guesses + 1)
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def to_dict(self, with_answer=True):
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"Returns this Riddle's properties in a dict, optionally including the answer"
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result = {
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"id": self.id,
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"question": self.question,
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"guesses": self.guesses,
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"correct": self.correct,
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"difficulty": self.difficulty(),
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}
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if with_answer:
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result["answer"] = self.answer
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return result
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def check_guess(self, guess):
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"""Checks whether a guess is correct and logs the attempt.
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We don't want to be too strict, so we will accept guesses which are close to the answer.
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Fuzzy string-matching is an interesting problem, which we will sidestep by using the
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`fuzzywuzzy` library. `FUZZ_RATIO` is our limit for how similar the answers have to be.
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Also, we don't care about upper-case and lower-case, so we'll cast everything to lower.
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For example, consider the riddle, "What's brown and sticky?" The answer, of course, is
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"A stick" Here are some attempts with their fuzz ratios:
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- "a stick" 100
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- "a stik" 92
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- "stick" 83
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- "it's a stick" 74
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- "idk" 40 """
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self.guesses += 1
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similarity = fuzz.ratio(guess.lower(), self.answer.lower())
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is_correct = similarity >= self.MIN_FUZZ_RATIO
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if is_correct:
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self.correct+= 1
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self.save()
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return is_correct
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