Source code for whalrus.rules.rule_sequential_tie_break

# -*- coding: utf-8 -*-
"""
Copyright Sylvain Bouveret, Yann Chevaleyre and Fran├žois 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.utils.utils import cached_property, NiceSet
from whalrus.rules.rule import Rule
from whalrus.rules.rule_plurality import RulePlurality
from whalrus.rules.rule_borda import RuleBorda
from whalrus.priorities.priority import Priority


[docs]class RuleSequentialTieBreak(Rule): """ A rule by sequential tie-break. Parameters ---------- args Cf. parent class. rules : list of Rule kwargs Cf. parent class. Examples -------- The winner is determined by the first rule. If there is a tie, it is broken by the second rule. Etc. There may still be a tie at the end: in that case, it is broken by the tie-breaking rule of this object. >>> rule = RuleSequentialTieBreak( ... ['a > d > e > b > c', 'b > d > e > a > c', 'c > d > e > a > b', ... 'd > e > b > a > c', 'e > d > b > a > c'], ... weights=[2, 2, 2, 1, 1], ... rules=[RulePlurality(), RuleBorda()], tie_break=Priority.ASCENDING) >>> rule.rules_[0].gross_scores_ {'a': 2, 'b': 2, 'c': 2, 'd': 1, 'e': 1} >>> rule.rules_[1].gross_scores_ {'a': 14, 'b': 14, 'c': 8, 'd': 25, 'e': 19} >>> rule.order_ [{'a', 'b'}, {'c'}, {'d'}, {'e'}] >>> rule.winner_ 'a' """ def __init__(self, *args, rules: list = None, **kwargs): self.rules = rules super().__init__(*args, **kwargs) @cached_property def rules_(self) -> list: """list: The rules (once applied to the profile). """ return [rule(self.profile_converted_) for rule in self.rules] @cached_property def order_(self) -> list: orders = [rule.order_ for rule in self.rules_] # rank_tuples[a] will be (rank in order 0, rank in order 1, ...) rank_tuples = {c: [] for c in self.candidates_} for order in orders: for i, tie_class in enumerate(order): for c in tie_class: rank_tuples[c].append(i) rank_tuples = {k: tuple(v) for k, v in rank_tuples.items()} # Now, sort by lexicographic order of "rank tuples" return [NiceSet(k for k in rank_tuples.keys() if rank_tuples[k] == v) for v in sorted(set(rank_tuples.values()))]
# TODO: some methods such as cowinners_ might be overridden for a better performance.