Slimmed down and perfected victories_and_ties function in condorcet.rb to match the...

[rubyvote] / lib / rubyvote / condorcet.rb

diff --git a/lib/rubyvote/condorcet.rb b/lib/rubyvote/condorcet.rb
index c0539abea5f02aa5b11ddda80fd41f68e78b9b8e..0c6fd5647bd921e5543838b42ddc297b57ca72cd 100644 (file)
--- a/lib/rubyvote/condorcet.rb
+++ b/lib/rubyvote/condorcet.rb
@@ -32,9 +32,7 @@
 ## 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
@@ -46,7 +44,6 @@ class CondorcetVote < ElectionVote
       end
     end
     super(votes)
-    @results = Array.new
   end
 
   def tally_vote(vote=nil)
@@ -86,53 +83,24 @@ class CondorcetVote < ElectionVote
     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)
+  def result
+    PureCondorcetResult.new(self)
   end
 end
 
 class CloneproofSSDVote < CondorcetVote
-  def resultFactory(init)
-    CloneproofSSDResult.new(init)
+  def result
+    CloneproofSSDResult.new(self)
   end
-
 end
 
 
@@ -144,21 +112,50 @@ 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
 
-  protected
+  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 = [candidates] unless candidates.class == Array
     candidates.each do |candidate|
       candidates.each do |challenger|
         next if candidate == challenger
@@ -170,6 +167,27 @@ class CondorcetResult < ElectionResult
 
     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
 
@@ -180,14 +198,15 @@ class PureCondorcetResult < CondorcetResult
   end
 
   protected
-
+  
   def condorcet
     votes = @election.votes
     candidates = @election.candidates
-    unless votes.length>0 and candidates.length>0
-      @winners=[nil]
-      return @winners
+
+    unless votes.length > 0 and candidates.length > 0
+      return @winners=[]
     end
+
     victors = Hash.new
     candidates.each do |candidate|
       victors[candidate] = Array.new
@@ -223,7 +242,7 @@ 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|