changed name of defeats_list to victories_and_ties

[rubyvote] / lib / rubyvote / condorcet.rb

diff --git a/lib/rubyvote/condorcet.rb b/lib/rubyvote/condorcet.rb
index e674115a89253359b62f18524280ed2c8f26c744..f86e59d1295cdc876b9d9f380892452c5f3bab04 100644 (file)
--- a/lib/rubyvote/condorcet.rb
+++ b/lib/rubyvote/condorcet.rb
@@ -32,7 +32,7 @@
 ## the CloneproofSSDVote classes but should not be used directly.
 
 class CondorcetVote < ElectionVote
-
+  
   attr_accessor :results
 
   def initialize(votes=nil)
@@ -51,9 +51,9 @@ class CondorcetVote < ElectionVote
 
   def tally_vote(vote=nil)
 
-    vote.each_with_index do |winner, index|
+    vote.each_with_index do |winners, index|
       if vote.flatten.length < @candidates.length
-        implied_losers = @candidates.select { |c| not vote.include?(c) }
+        implied_losers = @candidates.select { |c| not vote.flatten.include?(c) }
         vote.push(implied_losers)
       end
       if vote.length - 1 == index
@@ -66,18 +66,21 @@ class CondorcetVote < ElectionVote
         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
 
-          @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
+            # make sure we have a comparable object
+            @votes[loser][winner] = 0 unless @votes[loser].has_key?( winner )
           end
-
-          # make sure we have a comparable object
-          @votes[loser][winner] = 0 unless @votes[loser].has_key?( winner )
         end
       end
     end
@@ -120,8 +123,8 @@ class CondorcetVote < ElectionVote
 end
 
 class PureCondorcetVote < CondorcetVote
-  def result
-    PureCondorcetResult.new(self)
+  def resultFactory(init)
+    PureCondorcetResult.new(init)
   end
 end
 
@@ -141,21 +144,46 @@ 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
+    victors = Array.new
+    ties = Array.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
+    
+    victories = victors.sort {|a,b| b[2] <=> a[2]}
+    
+    return victories, ties    
+  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 = [candidates] unless candidates.class == Array
     candidates.each do |candidate|
       candidates.each do |challenger|
         next if candidate == challenger
@@ -177,10 +205,15 @@ class PureCondorcetResult < CondorcetResult
   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
@@ -191,11 +224,18 @@ class PureCondorcetResult < CondorcetResult
       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
 
@@ -209,7 +249,7 @@ class CloneproofSSDResult < CondorcetResult
 
   def cpssd
     votes = @election.votes
-    candidates = *@election.candidates
+    candidates = @election.candidates.dup
 
     def in_schwartz_set?(candidate, candidates, transitive_defeats)
       candidates.each do |challenger|