* Add a few testcases for checking for nonexistent things

[selectricity-live] / lib / rubyvote / condorcet.rb

diff --git a/lib/rubyvote/condorcet.rb b/lib/rubyvote/condorcet.rb
index c0539abea5f02aa5b11ddda80fd41f68e78b9b8e..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)
@@ -144,21 +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
@@ -180,14 +205,15 @@ 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 +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|