+class InstantRunoffVote < ElectionVote
+ def initialize(votes=nil)
+ @candidates = Array.new
+ votes.each do |vote|
+ @candidates = vote.uniq if vote.uniq.length > candidates.length
+ end
+ super(votes)
+ @candidates.each do |candidate|
+ @votes[candidate] = [0, Hash.new] unless @votes.has_key?(candidate)
+ end
+ end
+
+ def result(params={})
+ InstantRunoffResult.new(self, params)
+ end
+
+ protected
+ def tally_vote(vote)
+ votecopy = vote.dup
+ candidate = votecopy.shift
+ votes[candidate] = [0, Hash.new] unless votes.has_key?(candidate)
+ votes[candidate][0] += 1
+ if votes[candidate][1].has_key?(votecopy)
+ votes[candidate][1][votecopy] += 1
+ else
+ votes[candidate][1][votecopy] = 1
+ end
+ end
+
+ def verify_vote(vote=nil)
+ vote.instance_of?( Array ) and
+ vote == vote.uniq
+ end
+end
+
+class InstantRunoffLogicVote < InstantRunoffVote
+ def result(params={})
+ InstantRunoffLogicResult.new(self, params)
+ end
+end
+
+class InstantRunoffFirstRoundVote < InstantRunoffVote
+ def result(params={})
+ InstantRunoffFirstRoundResult.new(self, params)
+ end
+end
+
+class InstantRunoffAllVote < InstantRunoffVote
+ def result(params={})
+ InstantRunoffAllResult.new(self, params)
+ end
+end
+
+class InstantRunoffRandomVote < InstantRunoffVote
+ def result(params={})
+ InstantRunoffRandomResult.new(self, params)
+ end
+end
+
+class InstantRunoffResult < ElectionResult
+ attr_reader :ranked_candidates
+
+ def initialize(voteobj=nil, params={})
+ unless voteobj and voteobj.kind_of?( InstantRunoffVote )
+ raise ArgumentError, "You must pass an InstantRunoffVote array.", caller
+ end
+ super(voteobj)
+
+ votes = @election.votes.clone
+ candidates = @election.candidates
+ votes_sum = votes.inject(0) {|n, value| n + value[1][0]}
+ @majority = votes_sum/2 + 1
+ @ranked_candidates = Array.new()
+ ranked_candidates = Array.new()
+ losers = Array.new()
+
+ if params.has_key?('candidate_count')
+ apply_candidate_count(votes, params['candidate_count'])
+ end
+ if params.has_key?('vote_minimum')
+ apply_vote_minimum(votes, params['vote_minimum'])
+ end
+ if params.has_key?('percent_minimum')
+ apply_vote_minimum(votes, votes_sum * params['percent_minimum'])
+ end
+ if params.has_key?('percent_retention')
+ apply_retention(votes, votes_sum * params['percent_retention'])
+ end
+
+ begin
+ ranked_candidates = votes.sort do |a, b|
+ b[1][0] <=> a[1][0]
+ end.collect {|i| i[0]}
+ @winners = ranked_candidates.find_all do |i|
+ votes[i][0] >= @majority
+ end
+ end while not self.winner? and next_round(votes, ranked_candidates)
+ @ranked_candidates.unshift(*ranked_candidates)
+ end
+
+protected
+ def apply_candidate_count(votes, candidate_count)
+ if votes.size > candidate_count
+ losers = votes.sort do |a, b|
+ b[1][0] <=> a[1][0]
+ end.collect {|i| i[0]}.last(votes.size - candidate_count)
+ @ranked_candidates.unshift(losers) unless losers.empty?
+ losers.each { |loser| remove_candidate(votes, loser) }
+ end
+ end
+
+ def apply_vote_minimum(votes, vote_minimum)
+ losers = votes.find_all do |i|
+ i[1][0] < vote_minimum
+ end.collect {|i| i[0]}
+ if losers.length == votes.size
+ votes.clear
+ else
+ @ranked_candidates.unshift(losers) unless losers.empty?
+ losers.each { |loser| remove_candidate(votes, loser) }
+ end
+ end
+
+ def apply_retention(votes, retention)
+ losers = votes.sort do |a, b|
+ b[1][0] <=> a[1][0]
+ end.collect {|i| i[0]}
+ partial_sum = 0
+ while partial_sum < retention
+ partial_sum += votes[losers.shift][0]
+ end
+ @ranked_candidates.unshift(losers) unless losers.empty?
+ losers.each { |loser| remove_candidate(votes, loser) }
+ end
+
+ def next_round(votes, ranked_candidates)
+ loser = ranked_candidates[-1]
+ if votes.empty? or votes[loser][0] == votes[ranked_candidates[-2]][0]
+ false
+ else
+ @ranked_candidates.unshift(loser)
+ remove_candidate(votes, loser)
+ true
+ end
+ end
+
+ def remove_candidate(votes, loser)
+ votes.each_pair do |candidate, morevotes|
+ hash = morevotes[1]
+ hash.each_pair do |vote, count|
+ hash.delete(vote)
+ vote.delete(loser)
+ hash[vote] = count
+ end
+ end
+ votes[loser][1].each_pair do |vote, count|
+ candidate = vote.shift
+ votes[candidate][0] += count
+ if votes[candidate][1].has_key?(vote)
+ votes[candidate][1][vote] += count
+ else
+ votes[candidate][1][vote] = count
+ end
+ end
+ votes.delete(loser)
+ end
+end
+
+class InstantRunoffLogicResult < InstantRunoffResult
+ def next_round(votes, ranked_candidates)
+ losers = ranked_candidates.find_all do |i|
+ votes[i][0] == votes[ranked_candidates[-1]][0]
+ end
+ if losers.inject(0) {|n, loser| n + votes[loser][0]} >= @majority
+ false
+ else
+ @ranked_candidates.unshift(losers)
+ losers.each do |loser|
+ remove_candidate(votes, loser)
+ end
+ true
+ end
+ end
+end
+
+class InstantRunoffFirstRoundResult < InstantRunoffResult
+ def next_round(votes, ranked_candidates)
+ losers = ranked_candidates.find_all do |i|
+ votes[i][0] == votes[ranked_candidates[-1]][0]
+ end
+ loser = losers.sort do |a, b|
+ @election.votes[a][0] <=> @election.votes[b][0]
+ end.last
+ @ranked_candidates.unshift(loser)
+ remove_candidate(votes, loser)
+ end
+end
+
+class InstantRunoffAllResult < InstantRunoffResult
+ def next_round(votes, ranked_candidates)
+ losers = ranked_candidates.find_all do |i|
+ votes[i][0] == votes[ranked_candidates[-1]][0]
+ end
+ if losers.length == ranked_candidates.length
+ false
+ else
+ @ranked_candidates.unshift(losers)
+ losers.each do |loser|
+ remove_candidate(votes, loser)
+ end
+ true
+ end
+ end
+end
+
+class InstantRunoffRandomResult < InstantRunoffResult
+ def next_round(votes, ranked_candidates)
+ losers = ranked_candidates.find_all do |i|
+ votes[i][0] == votes[ranked_candidates[-1]][0]
+ end
+ loser = losers[rand(losers.length)]
+ @ranked_candidates.unshift(loser)
+ remove_candidate(votes, loser)
+ end
+end
projects / rubyvote / commitdiff