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:

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'})  # doctest:+ELLIPSIS
<... 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.

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
gross_scores_as_floats_

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

Type:NiceDict
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
weights_as_floats_

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

Type:NiceDict
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