RuleSchulze¶

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

Schulze’s Rule.

A candidate is a Schulze winner if it has no defeat in the Schulze matrix.

Parameters:	args – Cf. parent class. converter (ConverterBallot) – Default: `ConverterBallotToOrder`. matrix_schulze (Matrix) – The Schulze matrix. Default: `MatrixSchulze`. kwargs – Cf. parent class.

Examples

>>> rule = RuleSchulze(['a > b > c', 'b > c > a', 'c > a > b'], weights=[4, 3, 2])
>>> rule.matrix_schulze_.as_array_
array([[0, Fraction(2, 3), Fraction(2, 3)],
       [Fraction(5, 9), 0, Fraction(7, 9)],
       [Fraction(5, 9), Fraction(5, 9), 0]], dtype=object)
>>> rule.winner_
'a'

cotrailers_¶

“Cotrailers” of the election, i.e. the candidates that fare worst in the election. This is the last equivalence class in order_. For example, in RuleScoreNum, it is the candidates that are tied for the worst score.

Type:	NiceSet

cowinners_¶

Cowinners of the election, i.e. the candidates that fare best in the election.. This is the first equivalence class in order_. For example, in RuleScoreNum, it is the candidates that are tied for the best score.

Type:	NiceSet

matrix_schulze_¶

The Schulze matrix (once computed with the given profile).

Type:	Matrix

n_candidates_¶

Number of candidates.

Type:	int

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