Code refactor
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e0c56c5b1d
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631fa432c6
GPG Key ID:
7234E476BF21C61A
@ -41,8 +41,7 @@ class BaseSTVCounter:
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if options is not None:
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self.options.update(options)
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def reset(self):
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self.candidates = SafeDict([(c, CountCard()) for c in self.election.candidates])
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self.exhausted = CountCard()
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self.loss_fraction = CountCard()
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@ -57,12 +56,55 @@ class BaseSTVCounter:
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self.candidates[candidate].state = CandidateState.WITHDRAWN
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__pragma__('noopov')
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def reset(self):
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"""
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Public function:
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Reset the count and perform the first step
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Subclasses must override this function
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"""
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raise NotImplementedError('Method not implemented')
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def step(self):
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"""
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Public function:
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Perform one step of the STV count
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"""
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# Step count cards
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self.step_count_cards()
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# Check if done
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result = self.check_if_done()
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if result:
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return result
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# Distribute surpluses
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result = self.distribute_surpluses()
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if result:
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return result
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# Insufficient winners and no surpluses to distribute
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# Exclude the lowest ranked hopeful
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result = self.exclude_candidate()
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if result:
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return result
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raise STVException('Unable to complete step')
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def step_count_cards(self):
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"""
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Reset the count cards for the beginning of a new step
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"""
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for candidate, count_card in self.candidates.items():
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count_card.step()
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self.exhausted.step()
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self.loss_fraction.step()
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def check_if_done(self):
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"""
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Check if the count can be completed
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"""
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# Have sufficient candidates been elected?
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if self.num_elected >= self.election.seats:
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@ -89,6 +131,11 @@ class BaseSTVCounter:
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self.quota
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)
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__pragma__('noopov')
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def distribute_surpluses(self):
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"""
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Distribute surpluses, if any
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"""
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# Do surpluses need to be distributed?
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__pragma__('opov')
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@ -112,13 +159,13 @@ class BaseSTVCounter:
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__pragma__('noopov')
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# Transfer surplus
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self.transfer_surplus(candidate_surplus, count_card, surplus)
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self.do_surplus(candidate_surplus, count_card, surplus)
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__pragma__('opov')
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count_card.transfers -= surplus
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__pragma__('noopov')
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# Declare any candidates meeting the quota as a result of surpluses
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# Declare elected any candidates meeting the quota as a result of surpluses
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self.compute_quota()
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self.elect_meeting_quota()
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@ -132,9 +179,19 @@ class BaseSTVCounter:
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self.quota
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)
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__pragma__('noopov')
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def do_surplus(self, candidate_surplus, count_card, surplus):
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"""
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Transfer the surplus of the given candidate
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Subclasses must override this function
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"""
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raise NotImplementedError('Method not implemented')
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def exclude_candidate(self):
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"""
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Exclude the lowest ranked hopeful
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"""
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# Insufficient winners and no surpluses to distribute
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# Exclude the lowest ranked hopeful
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hopefuls = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL]
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hopefuls.sort(lambda x: x[1].votes)
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@ -143,7 +200,7 @@ class BaseSTVCounter:
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count_card.state = CandidateState.EXCLUDED
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# Exclude this candidate
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self.exclude_candidate(candidate_excluded, count_card)
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self.do_exclusion(candidate_excluded, count_card)
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__pragma__('opov')
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count_card.transfers -= count_card.votes
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@ -164,8 +221,18 @@ class BaseSTVCounter:
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)
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__pragma__('noopov')
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def do_exclusion(self, candidate_excluded, count_card):
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"""
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Exclude the given candidate and transfer the votes
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Subclasses must override this function
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"""
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raise NotImplementedError('Method not implemented')
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def compute_quota(self):
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"""Recount total votes and (if applicable) recalculate the quota"""
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"""
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Recount total votes and (if applicable) recalculate the quota
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"""
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__pragma__('opov')
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self.total = sum((cc.votes for c, cc in self.candidates.items()), Num('0'))
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self.loss_fraction.transfers += (self.total_orig - self.total - self.exhausted.votes) - self.loss_fraction.votes
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@ -184,6 +251,10 @@ class BaseSTVCounter:
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__pragma__('noopov')
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def meets_quota(self, count_card):
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"""
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Determine if the given candidate meets the quota
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"""
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if self.options['quota_criterion'] == 'geq':
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__pragma__('opov')
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return count_card.votes >= self.quota
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@ -196,6 +267,10 @@ class BaseSTVCounter:
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raise STVException('Invalid quota criterion')
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def elect_meeting_quota(self):
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"""
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Elect all candidates meeting the quota
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"""
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# Does a candidate meet the quota?
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meets_quota = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL and self.meets_quota(cc)]
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@ -212,8 +287,6 @@ class BaseWIGSTVCounter(BaseSTVCounter):
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"""
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def reset(self):
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BaseSTVCounter.reset(self)
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# Distribute first preferences
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for ballot in self.election.ballots:
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__pragma__('opov')
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@ -242,7 +315,7 @@ class BaseWIGSTVCounter(BaseSTVCounter):
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)
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__pragma__('noopov')
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def transfer_surplus(self, candidate_surplus, count_card, surplus):
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def do_surplus(self, candidate_surplus, count_card, surplus):
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for ballot, ballot_value in count_card.ballots:
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__pragma__('opov')
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new_value = (ballot_value * surplus) / count_card.votes # Multiply first to avoid rounding errors
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@ -257,7 +330,7 @@ class BaseWIGSTVCounter(BaseSTVCounter):
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self.exhausted.ballots.append((ballot, new_value))
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__pragma__('noopov')
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def exclude_candidate(self, candidate_excluded, count_card):
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def do_exclusion(self, candidate_excluded, count_card):
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for ballot, ballot_value in count_card.ballots:
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__pragma__('opov')
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candidate = next((c for c in ballot.preferences if self.candidates[c].state == CandidateState.HOPEFUL), None)
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@ -276,8 +349,6 @@ class BaseUIGSTVCounter(BaseSTVCounter):
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"""
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def reset(self):
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BaseSTVCounter.reset(self)
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# Distribute first preferences
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for ballot in self.election.ballots:
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__pragma__('opov')
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@ -306,7 +377,7 @@ class BaseUIGSTVCounter(BaseSTVCounter):
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)
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__pragma__('noopov')
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def transfer_surplus(self, candidate_surplus, count_card, surplus):
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def do_surplus(self, candidate_surplus, count_card, surplus):
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# FIXME: Is it okay to use native int's here?
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next_preferences = SafeDict([(c, []) for c, cc in self.candidates.items()])
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next_exhausted = []
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@ -352,7 +423,7 @@ class BaseUIGSTVCounter(BaseSTVCounter):
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__pragma__('noopov')
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self.exhausted.ballots.append((ballot, new_value))
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def exclude_candidate(self, candidate_excluded, count_card):
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def do_exclusion(self, candidate_excluded, count_card):
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next_preferences = SafeDict([(c, Rational('0')) for c, cc in self.candidates.items()])
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next_exhausted = Rational('0')
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total_votes = Rational('0')
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