RuleBucklinByRounds¶

class
whalrus.
RuleBucklinByRounds
(*args, converter: whalrus.converters_ballot.converter_ballot.ConverterBallot = None, scorer: whalrus.scorers.scorer_bucklin.ScorerBucklin = None, **kwargs)[source]¶ Bucklin’s rule (round by round version).
During the first round, a candidate’s score is the proportion of voters who rank it first. During the second round, its score is the proportion of voters who rank it first or second. Etc. More precisely, at each round, the
scorer
is used withk
equal to the round number; cf.ScorerBucklin
.For another variant of Bucklin’s rule, cf.
RuleBucklinInstant
.Parameters:  args – Cf. parent class.
 converter (ConverterBallot) – Default:
ConverterBallotToOrder
.  scorer (Scorer) – Default:
ScorerBucklin
.  kwargs – Cf. parent class.
Examples
>>> rule = RuleBucklinByRounds(['a > b > c > d', 'b > a > c > d', ... 'c > a > b > d', 'd > a > b > c']) >>> rule.detailed_scores_[0] {'a': Fraction(1, 4), 'b': Fraction(1, 4), 'c': Fraction(1, 4), 'd': Fraction(1, 4)} >>> rule.detailed_scores_[1] {'a': 1, 'b': Fraction(1, 2), 'c': Fraction(1, 4), 'd': Fraction(1, 4)} >>> rule.n_rounds_ 2 >>> rule.scores_ {'a': 1, 'b': Fraction(1, 2), 'c': Fraction(1, 4), 'd': Fraction(1, 4)} >>> rule.winner_ 'a'

average_score_
¶ The average score.
Type: Number

average_score_as_float_
¶ The average score as a float. It is the same as
average_score_
, but converted to a float.Type: float

best_score_as_float_
¶ The best score as a float. It is the same as
RuleScore.best_score_
, but converted to a float.Type: float

compare_scores
(one: numbers.Number, another: numbers.Number) → int¶ Compare two scores.
Parameters:  one (object) – A score.
 another (object) – A score.
Returns: 0 if they are equal, a positive number if
one
is greater thananother
, a negative number otherwise.Return type: int

detailed_scores_
¶ Detailed scores. A list of
NiceDict
. The first dictionary gives the scores of the first round, etc.Type: list

detailed_scores_as_floats_
¶ Detailed scores, as floats. It is the same as
detailed_scores_
, but converted to floats.Examples
>>> rule = RuleBucklinByRounds(['a > b > c > d', 'b > a > c > d', ... 'c > a > b > d', 'd > a > b > c']) >>> rule.detailed_scores_as_floats_[0] {'a': 0.25, 'b': 0.25, 'c': 0.25, 'd': 0.25} >>> rule.detailed_scores_as_floats_[1] {'a': 1.0, 'b': 0.5, 'c': 0.25, 'd': 0.25}
Type: list

n_candidates_
¶ Number of candidates.
Type: int

n_rounds_
¶ The number of rounds.
Type: int

scores_
¶ The scores. For each candidate, it gives its score during the final round, i.e. the first round where at least one candidate has a score above 1 / 2.
Type: NiceDict

scores_as_floats_
¶ Scores as floats. It is the same as
scores_
, but converted to floats.Type: NiceDict

strict_order_
¶ Result of the election as a strict order over the candidates. The first element is the winner, etc. This may use the tiebreaking rule.
Type: list

trailer_
¶ The “trailer” of the election. This is the last candidate in
strict_order_
and also the unfavorable choice of the tiebreaking rule incotrailers_
.Type: object

winner_
¶ The winner of the election. This is the first candidate in
strict_order_
and also the choice of the tiebreaking rule incowinners_
.Type: object

worst_score_as_float_
¶ The worst score as a float. It is the same as
RuleScore.worst_score_
, but converted to a float.Type: float