## the CloneproofSSDVote classes but should not be used directly.
class CondorcetVote < ElectionVote
+
+ def initialize(votes=nil)
+ unless defined?(@candidates)
+ @candidates = Array.new
+ votes.each do |vote_row|
+ vote_row = vote_row.flatten if vote_row.class == Array
+ vote_row.each do |vote|
+ @candidates << vote unless @candidates.include?(vote)
+ end
+ end
+ end
+ super(votes)
+ end
def tally_vote(vote=nil)
- vote.each_with_index do |winner, index|
- # only run through this if this *is* preferred to something
- break if vote.length - 1 == index
- losers = vote.last( vote.length - index )
-
- losers.each do |loser|
- next if winner == loser
+ vote.each_with_index do |winners, index|
+ if vote.flatten.length < @candidates.length
+ implied_losers = @candidates.select { |c| not vote.flatten.include?(c) }
+ vote.push(implied_losers)
+ end
+ if vote.length - 1 == index
+ losers = []
+ else
+ losers = vote.flatten.last( vote.flatten.length - index - 1)
+ end
- @votes[winner] = Hash.new unless @votes.has_key?(winner)
- @votes[loser] = Hash.new unless @votes.has_key?(loser)
+ losers.each do |place|
+ place = [place] unless place.class == Array
+ place.each do |loser|
+
+ winners = [winners] unless winners.class == Array
+ next if winners.include?(loser)
+ winners.each do |winner|
+ @votes[winner] = Hash.new unless @votes.has_key?(winner)
+ @votes[loser] = Hash.new unless @votes.has_key?(loser)
+
+ if @votes[winner].has_key?(loser)
+ @votes[winner][loser] += 1
+ else
+ @votes[winner][loser] = 1
+ end
- if @votes[winner].has_key?(loser)
- @votes[winner][loser] += 1
- else
- @votes[winner][loser] = 1
+ # make sure we have a comparable object
+ @votes[loser][winner] = 0 unless @votes[loser].has_key?( winner )
+ end
end
-
- # make sure we have a comparable object
- @votes[loser][winner] = 0 unless @votes[loser].has_key?( winner )
-
- @candidates << loser unless @candidates.include?( loser )
end
-
- @candidates << winner unless @candidates.include?( winner )
end
end
protected
+
def verify_vote(vote=nil)
vote.instance_of?( Array ) and
vote == vote.uniq
end
-
end
class PureCondorcetVote < CondorcetVote
def result
- PureCondorcetResult.new( self )
+ PureCondorcetResult.new(self)
end
end
class CloneproofSSDVote < CondorcetVote
def result
- CloneproofSSDResult.new( self )
+ CloneproofSSDResult.new(self)
end
end
## directly.
class CondorcetResult < ElectionResult
+ attr_reader :matrix
+
def initialize(voteobj=nil)
unless voteobj and voteobj.kind_of?( CondorcetVote )
raise ArgumentError, "You must pass a CondorcetVote array.", caller
end
super(voteobj)
+ @matrix = voteobj.votes
+ end
+
+ def victories_and_ties
+ victories_ties = {}
+ candidates = @matrix.keys.sort
+
+ candidates.each do |candidate|
+ candidates.each do |challenger|
+ next if candidate == challenger
+ diff = @matrix[candidate][challenger] - @matrix[challenger][candidate]
+ victories_ties[candidate] = {} unless victories_ties.key?(candidate)
+ if diff >= 0
+ victories_ties[candidate][challenger] = diff
+ end
+ end
+ end
+
+ return victories_ties
end
+ def ranked_candidates
+ if not defined?(@ranked_candidates)
+ @ranked_candidates = build_ranked_candidates()
+ end
+
+ @ranked_candidates
+ end
+
+ protected
def defeats(candidates=nil, votes=nil)
- candidates = @election.candidates unless candidates
- votes = @election.votes unless votes
+ candidates ||= @election.candidates || []
+ # we're assumign that if there are candidates, there must be at
+ # least one vote for them
+ votes ||= @election.votes
defeats = Array.new
candidates.each do |candidate|
defeats
end
+
+ def build_ranked_candidates
+ # build a lis of ranked candidates by dropping the winner and
+ # cursing
+
+ ranked_candidates = []
+
+ resultobj = self.dup
+ candidates = self.election.candidates
+
+ until candidates.empty?
+ ranked_candidates << resultobj.winners
+
+ new_voteobj = resultobj.election.dup
+ candidates = new_voteobj.candidates
+ new_voteobj.candidates.delete_if {|x| resultobj.winners.include?(x)}
+ resultobj = new_voteobj.result
+ end
+
+ ranked_candidates
+ end
end
end
protected
+
def condorcet
votes = @election.votes
candidates = @election.candidates
+ unless votes.length > 0 and candidates.length > 0
+ return @winners=[]
+ end
+
victors = Hash.new
candidates.each do |candidate|
victors[candidate] = Array.new
victors[winner] << loser
end
- winners = @election.candidates.find_all do |candidate|
- victors[candidate].length == @election.candidates.length - 1
+ victory_margin = 1
+ while true
+ winners = @election.candidates.find_all do |candidate|
+ victors[candidate].length == @election.candidates.length - victory_margin
+ end
+ if winners.length > 0
+ @winners = winners
+ return @winners
+ else
+ victory_margin += 1
+ end
end
-
- @winners << winners if winners.length == 1
end
end
end
protected
+
def cpssd
votes = @election.votes
- candidates = *@election.candidates
+ candidates = @election.candidates.dup
def in_schwartz_set?(candidate, candidates, transitive_defeats)
candidates.each do |challenger|
# see the array with the standard defeats
transitive_defeats = self.defeats(candidates, votes)
+ defeats_hash = Hash.new
+ transitive_defeats.each { |td| defeats_hash[td] = 1 }
+ candidates = [candidates] unless candidates.class == Array
candidates.each do |cand1|
candidates.each do |cand2|
- candidates.each do |cand3|
- if transitive_defeats.include?( [ cand2, cand1 ] ) and
- transitive_defeats.include?( [ cand1, cand3 ] ) and
- not transitive_defeats.include?( [ cand2, cand3 ] ) and
- not cand2 == cand3
- transitive_defeats << [ cand2, cand3 ]
+ unless cand1 == cand2
+ candidates.each do |cand3|
+ if not cand2 == cand3 and
+ not cand1 == cand3 and
+ defeats_hash[[cand2, cand1]] and
+ defeats_hash[[cand1, cand3]] and
+ not defeats_hash[[cand2, cand3]]
+ transitive_defeats << [cand2, cand3]
+ defeats_hash[[cand2, cand3]] = 1
+ end
end
end
end
projects / selectricity / blobdiff