# -*- 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.ballots.ballot_plurality import BallotPlurality
from whalrus.utils.utils import cached_property, NiceDict
from whalrus.scorers.scorer import Scorer
[docs]class ScorerPlurality(Scorer):
"""
A Plurality scorer for :class:`BallotPlurality`.
Parameters
----------
args
Cf. parent class.
count_abstention : bool
If False (default), then an abstention grants no score at all. If True, then an abstention gives 0 point to
each candidate (cf. below).
kwargs
Cf. parent class.
Examples
--------
Typical usage:
>>> ScorerPlurality(BallotPlurality('a'), candidates={'a', 'b', 'c'}).scores_
{'a': 1, 'b': 0, 'c': 0}
Using the option ``count_abstention``:
>>> ScorerPlurality(BallotPlurality(None), candidates={'a', 'b', 'c'}).scores_
{}
>>> ScorerPlurality(BallotPlurality(None), candidates={'a', 'b', 'c'},
... count_abstention=True).scores_
{'a': 0, 'b': 0, 'c': 0}
"""
def __init__(self, *args, count_abstention: bool = False, **kwargs):
self.count_abstention = count_abstention
super().__init__(*args, **kwargs)
@cached_property
def scores_(self) -> NiceDict:
if self.ballot_.candidate is None:
if self.count_abstention:
return NiceDict({c: 0 for c in self.candidates_})
else:
return NiceDict()
scores = NiceDict({c: 0 for c in self.candidates_})
scores[self.ballot_.candidate] = 1
return scores