# -*- 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_levels import BallotLevels
from whalrus.utils.utils import cached_property, NiceDict
from whalrus.scorers.scorer import Scorer
[docs]class ScorerLevels(Scorer):
"""
A standard scorer for :class:``BallotLevel``.
Parameters
----------
args
Cf. parent class.
level_ungraded : object
The level of the scale used for ungraded candidates, or None.
level_absent : object
The level of the scale used for absent candidates, or None.
kwargs
Cf. parent class.
Examples
--------
In the most general syntax, firstly, you define the scorer:
>>> scorer = ScorerLevels(level_absent=0)
Secondly, you use it as a callable to load some particular arguments:
>>> scorer(ballot=BallotLevels({'a': 10, 'b': 7, 'c': 3}), voter='Alice',
... candidates={'a', 'b', 'c', 'd'}) # doctest:+ELLIPSIS
<... object at ...>
Finally, you can access the computed variables:
>>> scorer.scores_
{'a': 10, 'b': 7, 'c': 3, 'd': 0}
Later, if you wish, you can load other arguments (ballot, etc) with the same scorer, and so on.
Optionally, you can specify arguments as soon as the :class:`Scorer` object is initialized. This allows for
"one-liners" such as:
>>> ScorerLevels(ballot=BallotLevels({'a': 10, 'b': 7, 'c': 3}), voter='Alice',
... candidates={'a', 'b', 'c', 'd'}, level_absent=0).scores_
{'a': 10, 'b': 7, 'c': 3, 'd': 0}
In the example below, candidates `a`, `b` and `c` are "ordered", `d` is "unordered", and `e` is "absent"
in the ballot, meaning that `e` were not even available when the voter cast her ballot. The options of the
scorer provide different ways to take these special cases into account:
>>> ballot=BallotLevels({'a': 10, 'b': 7, 'c': 3}, candidates={'a', 'b', 'c', 'd'})
>>> candidates_election = {'a', 'b', 'c', 'd', 'e'}
>>> ScorerLevels(ballot, candidates=candidates_election).scores_
{'a': 10, 'b': 7, 'c': 3}
>>> ScorerLevels(ballot, candidates=candidates_election,
... level_ungraded=-5).scores_
{'a': 10, 'b': 7, 'c': 3, 'd': -5}
>>> ScorerLevels(ballot, candidates=candidates_election,
... level_ungraded=-5, level_absent=-10).scores_
{'a': 10, 'b': 7, 'c': 3, 'd': -5, 'e': -10}
"""
def __init__(self, *args, level_ungraded: object = None, level_absent: object = None, **kwargs):
self.level_ungraded = level_ungraded
self.level_absent = level_absent
super().__init__(*args, **kwargs)
@cached_property
def scores_(self) -> NiceDict:
scores = NiceDict(self.ballot_.as_dict.copy())
if self.level_absent is not None:
scores.update({c: self.level_absent for c in self.candidates_ - self.ballot_.candidates})
if self.level_ungraded is not None:
scores.update({c: self.level_ungraded for c in self.ballot_.candidates_not_in_b})
return scores