RulePlurality¶

class whalrus.RulePlurality(*args, converter: whalrus.converters_ballot.converter_ballot.ConverterBallot = None, scorer: whalrus.scorers.scorer.Scorer = None, **kwargs)[source]¶

The plurality rule.

Parameters

args – Cf. parent class.
converter (ConverterBallot) – Default: ConverterBallotToPlurality.
scorer (Scorer) – Default: ScorerPlurality.
kwargs – Cf. parent class.

Examples

In the most general syntax, firstly, you define the rule:

>>> plurality = RulePlurality(tie_break=Priority.ASCENDING)

Secondly, you use it as a callable to load a particular election (profile, candidates):

>>> plurality(ballots=['a', 'b', 'c'], weights=[2, 2, 1], voters=['Alice', 'Bob', 'Cate'],
...           candidates={'a', 'b', 'c', 'd'})  
<... object at ...>

Finally, you can access the computed variables:

>>> plurality.gross_scores_
{'a': 2, 'b': 2, 'c': 1, 'd': 0}
>>> plurality.winner_
'a'

Later, if you wish, you can load another profile with the same voting rule, and so on.

Optionally, you can specify an election (profile and candidates) as soon as the Rule object is initialized. This allows for one-liners such as:

>>> RulePlurality(['a', 'a', 'b', 'c']).winner_
'a'

Cf. Rule for more information about the arguments.

property average_score_¶

The average score.

Type: Number

property average_score_as_float_¶

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

Type: float

property 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

property cotrailers_¶

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

Type: NiceSet

property cowinners_¶

Cowinners. The set of candidates with the best score.

Type: NiceSet

property gross_scores_as_floats_¶

Gross scores as floats. It is the same as gross_scores_, but converted to floats.

Type: NiceDict

property n_candidates_¶

Number of candidates.

Type: int

property scores_as_floats_¶

Scores as floats. It is the same as scores_, but converted to floats.

Type: NiceDict

property 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

property 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

property weights_as_floats_¶

Weights as floats. It is the same as weights_, but converted to floats.

Type: NiceDict

property 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

property 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