eo/src/eoLottery.h

@@ -0,0 +1,60 @@
+//-----------------------------------------------------------------------------
+// eoLottery.h
+//-----------------------------------------------------------------------------
+
+#ifndef eoLottery_h
+#define eoLottery_h
+
+//-----------------------------------------------------------------------------
+
+#include <eo>
+
+//-----------------------------------------------------------------------------
+// eoLottery
+//-----------------------------------------------------------------------------
+
+template<class Chrom> class eoLottery: public eoSelect<Chrom>
+{
+ public:
+  eoLottery(const float& rate = 1.0): eoLottery(rate) {}
+  
+  void operator()(const eoPop<Chrom>& pop, eoPop<Chrom>& breeders)
+    {
+      // scores of chromosomes
+      vector<float> score(pop.size());
+      
+      // calculates accumulated scores for chromosomes
+      transform(pop.begin(), pop.end(), score.begin(), fitness);
+      float sum = accumulate(score.begin(), score.end(), MINFLOAT);
+      transform(score.begin(), score.end(), score.begin(), 
+		bind2nd(divides<float>(), sum));
+      partial_sum(score.begin(), score.end(), score.begin());
+      
+      // generates random numbers
+      vector<float> random(pop.size());
+      generate(random.begin(), random.end(), Uniform<float>(0,1));
+      sort(random.begin(), random.end(), less<float>());
+
+      // selection of chromosomes
+      unsigned score_index = 0;   // position in score vector
+      unsigned random_index = 0;  // position in random vector
+      unsigned num_chroms = (unsigned)(rate * pop.size());
+      do {
+	if(random[random_index] < score[score_index]) 
+	  {
+	    breeders.push_back(pop[score_index]);
+	    random_index++;
+	  }
+	else
+	  if (score_index < pop.size())
+	    score_index++;
+	  else
+	    fill_n(back_insert_iterator<Pop>(breeders), 
+		   num_chroms - breeders.size(), pop.back());
+      } while (breeders.size() < num_chroms);
+    }
+};
+
+//-----------------------------------------------------------------------------
+
+#endif eoLottery_h