Cleaned up after Justin's last commit.

git-svn-id: svn://rubyforge.org/var/svn/rubyvote/trunk@45 1440c7f4-e209-0410-9a04-881b5eb134a8

diff --git a/lib/condorcet.rb b/lib/condorcet.rb
deleted file mode 100644 (file)
index a78524b..0000000
--- a/lib/condorcet.rb
+++ /dev/null
@@ -1,344 +0,0 @@
-# election library -- a ruby library for elections
-# copyright © 2005 MIT Media Lab and Benjamin Mako Hill
-
-# This program 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 2 of the License, or
-# (at your option) any later version.
-
-# This program 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 this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-# 02110-1301, USA.
-
-#################################################################
-## ==== condorcet.rb ====
-##
-## This file contains Condorcet election methods. Currently this
-## includes a pure condorcet and a CloneproofSSD implementation
-## modeled after the Python-based Debian project election code and
-## that gives the same results in several tested corner cases.
-#################################################################
-
-##################################################################
-## CondorcetVote Classes and SubClasses
-##
-## The CondorcetVote class is subclassed by the PureCondorcetVote and
-## the CloneproofSSDVote classes but should not be used directly.
-
-class CondorcetVote < ElectionVote
-  
-  attr_accessor :results
-
-  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)
-    @results = Array.new
-  end
-
-  def tally_vote(vote=nil)
-
-    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
-
-      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
-
-            # make sure we have a comparable object
-            @votes[loser][winner] = 0 unless @votes[loser].has_key?( winner )
-          end
-        end
-      end
-    end
-  end
-
-  def results
-    if @results.size < 2 && (not @candidates.empty?)
-      tabulate
-    end
-    @results
-  end
-
-  def result
-    find_only_winner unless @winner
-    @winner
-  end
-
-  protected
-
-  def verify_vote(vote=nil)
-    vote.instance_of?( Array ) and
-      vote == vote.uniq
-  end
-
-  def tabulate
-    find_only_winner unless @winner
-    until @candidates.empty? 
-      aResult = resultFactory( self )
-      @results << aResult.winners
-      filter_out(aResult)
-    end
-  end
-
-  def find_only_winner
-    @winner = resultFactory( self )
-    @results << @winner.winners
-    filter_out(@winner)
-  end
-
-end
-
-class PureCondorcetVote < CondorcetVote
-  def resultFactory(init)
-    PureCondorcetResult.new(init)
-  end
-end
-
-class CloneproofSSDVote < CondorcetVote
-  def resultFactory(init)
-    CloneproofSSDResult.new(init)
-  end
-
-end
-
-
-##################################################################
-## CondorcetResult Classes and SubClasses
-##
-## The CondorcetResult class is subclassed by the PureCondorcetResult
-## and the CloneproofSSDResult classes but should not be used
-## 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
-    victors = Array.new
-    ties = Array.new
-    victories = Hash.new
-    candidates = @matrix.keys.sort
-    
-    candidates.each do |candidate|
-      candidates.each do |challenger|
-        next if candidate == challenger
-        diff = @matrix[candidate][challenger] - @matrix[challenger][candidate]
-        if diff > 0 
-          victors << [candidate, challenger, diff]
-        elsif diff == 0 && ties.include?([challenger, candidate]) == false
-          ties << [candidate, challenger] 
-        end
-      end
-    end  
-    
-    victors.each do |list|
-      if victories.has_key?(list[0])
-        victories[list[0]][list[1]] = list[2]       
-      else
-        victories[list[0]] = Hash.new
-        victories[list[0]][list[1]] = list[2]
-      end
-    end
-    
-    return victories, ties    
-  end
-        
-  protected
-  def defeats(candidates=nil, votes=nil)
-    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|
-      candidates.each do |challenger|
-        next if candidate == challenger
-        if votes[candidate][challenger] > votes[challenger][candidate]
-          defeats << [ candidate, challenger ]
-        end
-      end
-    end
-
-    defeats
-  end
-
-end
-
-class PureCondorcetResult < CondorcetResult
-  def initialize(voteobj=nil)
-    super(voteobj)
-    self.condorcet()
-  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
-    end
-
-    self.defeats.each do |pair|
-      winner, loser = *pair
-      victors[winner] << loser
-    end
-
-    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
-  end
-end
-
-class CloneproofSSDResult < CondorcetResult
-  def initialize(voteobj=nil)
-    super(voteobj)
-    @winners = self.cpssd()
-  end
-
-  protected
-
-  def cpssd
-    votes = @election.votes
-    candidates = @election.candidates.dup
-
-    def in_schwartz_set?(candidate, candidates, transitive_defeats)
-      candidates.each do |challenger|
-        next if candidate == challenger
-
-        if transitive_defeats.include?( [ challenger, candidate ] ) and
-            not transitive_defeats.include?( [ candidate, challenger ] )
-          return false
-        end
-      end
-      return true
-    end
-
-    loop do
-
-      # 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|
-          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
-      end
-
-      schwartz_set = Array.new
-      candidates.each do |candidate|
-        if in_schwartz_set?(candidate, candidates, transitive_defeats)
-          schwartz_set << candidate
-        end
-      end
-
-      candidates = schwartz_set
-
-      # look through the schwartz set now for defeats
-      defeats = self.defeats(candidates, votes)
-      
-      # it's a tie or there's only one option
-      break if defeats.length == 0
-
-      def is_weaker_defeat?( pair1, pair2 )
-        votes = @election.votes
-        if votes[pair1[0]][pair1[1]] > votes[pair2[0]][pair2[1]]
-          return true
-        elsif votes[pair1[0]][pair1[1]] == votes[pair2[0]][pair2[1]] and
-            votes[pair1[1]][pair1[0]] > votes[pair2[1]][pair2[0]]
-          return true
-        else
-          false
-        end
-      end
-      
-      defeats.sort! do |pair1, pair2|
-        if is_weaker_defeat?( pair1, pair2 ) 
-          +1
-        elsif is_weaker_defeat?( pair2, pair1 ) 
-          -1
-        else
-          0
-        end
-      end
- 
-      votes[defeats[0][0]][defeats[0][1]] = 0
-      votes[defeats[0][1]][defeats[0][0]] = 0
-      
-    end
-
-    return candidates
-  end
-
-end

diff --git a/lib/rubyvote/condorcet.rb b/lib/rubyvote/condorcet.rb
index f86e59d1295cdc876b9d9f380892452c5f3bab04..a78524b7003dd7eaa5d589c9af671a7551fde611 100644 (file)
--- a/lib/rubyvote/condorcet.rb
+++ b/lib/rubyvote/condorcet.rb
@@ -157,6 +157,7 @@ class CondorcetResult < ElectionResult
   def victories_and_ties
     victors = Array.new
     ties = Array.new
+    victories = Hash.new
     candidates = @matrix.keys.sort
     
     candidates.each do |candidate|
@@ -169,9 +170,16 @@ class CondorcetResult < ElectionResult
           ties << [candidate, challenger] 
         end
       end
-    end
+    end  
     
-    victories = victors.sort {|a,b| b[2] <=> a[2]}
+    victors.each do |list|
+      if victories.has_key?(list[0])
+        victories[list[0]][list[1]] = list[2]       
+      else
+        victories[list[0]] = Hash.new
+        victories[list[0]][list[1]] = list[2]
+      end
+    end
     
     return victories, ties    
   end