ConverterBallotToLevelsInterval

class whalrus.ConverterBallotToLevelsInterval(scale: whalrus.scales.scale.Scale = ScaleInterval(low=0, high=1), borda_unordered_give_points: bool = True)

0 Default converter to a BallotLevels using a ScaleInterval (interval of real numbers).

Parameters:

• scale (ScaleInterval) –
• borda_unordered_give_points (bool) – When converting a BallotOrder that is not a BallotLevels, we use Borda scores (normalized to the interval [scale.low, scale.high]. This parameter decides whether the unordered candidates of the ballot give points to the ordered candidates. Cf. ScorerBorda.

Examples

Typical usages:

>>> converter = ConverterBallotToLevelsInterval()
>>> b = BallotLevels({'a': 1, 'b': .5}, candidates={'a', 'b', 'c'}, scale=ScaleInterval(-1, 1))
>>> converter(b).as_dict
{'a': 1, 'b': Fraction(3, 4)}
>>> b = BallotLevels({'a': 5, 'b': 4}, candidates={'a', 'b', 'c'}, scale=ScaleRange(0, 5))
>>> converter(b).as_dict
{'a': 1, 'b': Fraction(4, 5)}
>>> b = BallotLevels({'a': 3, 'b': 0}, candidates={'a', 'b', 'c'}, scale=ScaleFromSet({-1, 0, 3}))
>>> converter(b).as_dict
{'a': 1, 'b': Fraction(1, 4)}
>>> b = BallotLevels({'a': 'Excellent', 'b': 'Very Good'}, candidates={'a', 'b', 'c'},
...                  scale=ScaleFromList(['Bad', 'Medium', 'Good', 'Very Good', 'Excellent']))
>>> converter(b).as_dict
{'a': 1, 'b': Fraction(3, 4)}
>>> converter(BallotOneName('a', candidates={'a', 'b', 'c'})).as_dict
{'a': 1, 'b': 0, 'c': 0}
>>> converter(BallotPlurality('a', candidates={'a', 'b', 'c'})).as_dict
{'a': 1, 'b': 0, 'c': 0}
>>> converter(BallotVeto('a', candidates={'a', 'b', 'c'})).as_dict
{'a': 0, 'b': 1, 'c': 1}
>>> converter('a > b > c').as_dict
{'a': 1, 'b': Fraction(1, 2), 'c': 0}

Options for converting ordered ballots:

>>> b = BallotOrder('a > b > c', candidates={'a', 'b', 'c', 'd', 'e'})
>>> ConverterBallotToLevelsInterval(borda_unordered_give_points=False)(b).as_dict
{'a': 1, 'b': Fraction(1, 2), 'c': 0}
>>> ConverterBallotToLevelsInterval(borda_unordered_give_points=True)(b).as_dict
{'a': 1, 'b': Fraction(3, 4), 'c': Fraction(1, 2)}