# -*- coding: utf-8 -*-
"""
Copyright Sylvain Bouveret, Yann Chevaleyre and François Durand
sylvain.bouveret@imag.fr, yann.chevaleyre@dauphine.fr, fradurand@gmail.com
This file is part of Whalrus.
Whalrus is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Whalrus is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Whalrus. If not, see <http://www.gnu.org/licenses/>.
"""
from whalrus.rules.rule_score_num_average import RuleScoreNumAverage
from whalrus.scorers.scorer_positional import ScorerPositional
from whalrus.converters_ballot.converter_ballot_to_strict_order import ConverterBallotToStrictOrder
from whalrus.priorities.priority import Priority
from whalrus.converters_ballot.converter_ballot import ConverterBallot
[docs]class RuleScorePositional(RuleScoreNumAverage):
"""
A positional scoring rule.
Parameters
----------
args
Cf. parent class.
converter : ConverterBallot
Default: :class:`ConverterBallotToStrictOrder`.
points_scheme : list
The list of points to be attributed to the candidates of a ballot. Cf. :class:`ScorerPositional`.
kwargs
Cf. parent class.
Examples
--------
>>> RuleScorePositional(['a > b > c', 'b > c > a'], points_scheme=[3, 2, 1]).gross_scores_
{'a': 4, 'b': 5, 'c': 3}
Since this voting rule needs strict orders, problems may occur as soon as there is indifference in the ballots. To
avoid these issues, specify the ballot converter explicitly:
>>> RuleScorePositional(['a > b ~ c', 'b > c > a'], points_scheme=[1, 1, 0],
... converter=ConverterBallotToStrictOrder(priority=Priority.ASCENDING)).gross_scores_
{'a': 1, 'b': 2, 'c': 1}
"""
def __init__(self, *args, converter: ConverterBallot = None, points_scheme: list = None, **kwargs):
if converter is None:
converter = ConverterBallotToStrictOrder()
super().__init__(*args, converter=converter, scorer=ScorerPositional(points_scheme=points_scheme),
default_average=0, **kwargs)