RuleRankedPairs

class whalrus.RuleRankedPairs(*args, converter: whalrus.converters_ballot.converter_ballot.ConverterBallot = None, matrix: whalrus.matrices.matrix.Matrix = None, **kwargs)[source]

Ranked Pairs rule.

The score of a candidate is the number of victories in the ranked pairs matrix.

Parameters:

Examples

>>> rule = RuleRankedPairs(['a > b > c', 'b > c > a', 'c > a > b'], weights=[4, 3, 2])
>>> rule.matrix_.as_array_
array([[0, 1, 1],
       [0, 0, 1],
       [0, 0, 0]], dtype=object)
>>> rule.scores_
{'a': 2, 'b': 1, 'c': 0}
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 than another, a negative number otherwise.

Return type:

int

cotrailers_

“Cotrailers”. The set of candidates with the worst score.

Type:NiceSet
cowinners_

Cowinners. The set of candidates with the best score.

Type:NiceSet
matrix_

The matrix (once computed with the given profile).

Type:Matrix
matrix_ranked_pairs_

The ranked pairs matrix. Alias for matrix_.

Examples

>>> rule = RuleRankedPairs(['a > b > c', 'b > c > a', 'c > a > b'], weights=[4, 3, 2])
>>> rule.matrix_ranked_pairs_.as_array_
array([[0, 1, 1],
       [0, 0, 1],
       [0, 0, 0]], dtype=object)
Type:Matrix
n_candidates_

Number of candidates.

Type:int
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 tie-breaking rule.

Type:list
trailer_

The “trailer” of the election. This is the last candidate in strict_order_ and also the unfavorable choice of the tie-breaking rule in cotrailers_.

Type:object
winner_

The winner of the election. This is the first candidate in strict_order_ and also the choice of the tie-breaking rule in cowinners_.

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