History tracking stores the best individual per generation within the population and is now disabled by default.

src/javaeva/server/go/populations/Population.java

@@ -28,7 +28,8 @@ public class Population extends ArrayList implements PopulationInterface, Clonea
     protected int           m_Size          = 50;
     protected Population    m_Archive       = null;
 
-    public ArrayList        m_History       = new ArrayList();
+    boolean useHistory						= false;
+    public ArrayList<AbstractEAIndividual>  m_History       = new ArrayList<AbstractEAIndividual>();
 
     public Population() {
     }
@@ -84,6 +85,16 @@ public class Population extends ArrayList implements PopulationInterface, Clonea
         }
     }
 
+    /**
+     * Activate or deactivate the history tracking, which stores the best individual in every
+     * generation in the incrGeneration() method.
+     * 
+     * @param useHist
+     */
+    public void setUseHistory(boolean useHist) {
+    	useHistory = useHist;
+    }
+    
     /** This method will allow cou to increment the current number of function calls.
      */
     public void incrFunctionCalls() {
@@ -117,7 +128,7 @@ public class Population extends ArrayList implements PopulationInterface, Clonea
      * Stagnation measured etc. pp.
      */
     public void incrGeneration() {
-        if (this.size() >= 1) this.m_History.add(this.getBestEAIndividual());
+        if (useHistory && (this.size() >= 1)) this.m_History.add(this.getBestEAIndividual());
         for (int i=0; i<size(); i++) ((AbstractEAIndividual)get(i)).incrAge(); 
         this.m_Generation++;
     }
@@ -241,8 +252,8 @@ public class Population extends ArrayList implements PopulationInterface, Clonea
      * 
      */
     public Object[] getBestNIndividuals(int n) {
-    	LinkedList indList = new LinkedList();
+    	LinkedList<AbstractEAIndividual> indList = new LinkedList<AbstractEAIndividual>();
-    	PriorityQueue queue = new PriorityQueue(n);
+    	PriorityQueue<Double> queue = new PriorityQueue<Double>(n);
     	AbstractEAIndividual indy;
         double  curNBestFitness  = Double.POSITIVE_INFINITY;
 
@@ -253,7 +264,7 @@ public class Population extends ArrayList implements PopulationInterface, Clonea
                 	indList.removeLast();
                 	queue.remove();
                 }
-                indList.addFirst(super.get(i));
+                indList.addFirst((AbstractEAIndividual)super.get(i));
                 // use negative fitness, because queue orders the smallest to top.
                 queue.add(new Double(- indy.getFitness(0)));
                 if (indList.size() == n) curNBestFitness  = - ((Double)queue.peek()).doubleValue();

src/javaeva/server/go/strategies/ClusterBasedNichingEA.java

@@ -93,9 +93,11 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
     public void init() {
         this.m_Optimizer.addPopulationChangedEventListener(this);
         this.m_Undifferentiated = new Population();
+        this.m_Undifferentiated.setUseHistory(true);
         this.m_Undifferentiated.setPopulationSize(this.m_PopulationSize);
         this.m_Species = new ArrayList<Population>();
         this.m_Problem.initPopulation(this.m_Undifferentiated);
+        this.getPopulation().setUseHistory(true);
         this.evaluatePopulation(this.m_Undifferentiated);
         this.firePropertyChangedEvent("FirstGenerationPerformed");
     }
@@ -106,6 +108,7 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
      */
     public void initByPopulation(Population pop, boolean reset) {
         this.m_Optimizer.addPopulationChangedEventListener(this);
+        pop.setUseHistory(true);
         this.m_Undifferentiated = (Population)pop.clone();
         if (reset) this.m_Undifferentiated.init();
         this.m_Undifferentiated.setPopulationSize(this.m_PopulationSize);
@@ -241,6 +244,7 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
      */
     private Population initializeIndividuals(int n) {
         Population result = new Population();
+        result.setUseHistory(true);
         result.setPopulationSize(n);
         //@todo: crossover between species is to be impelemented
         this.m_Problem.initPopulation(result);
@@ -374,6 +378,7 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
                 ClusterResult   = this.m_CAForSpeciesDifferentation.cluster(this.m_Undifferentiated);
                 this.m_Undifferentiated = ClusterResult[0];
                 for (int j = 1; j < ClusterResult.length; j++) {
+                	ClusterResult[j].setUseHistory(true);
                     ClusterResult[j].m_History = new ArrayList();
                     newSpecies.add(ClusterResult[j]);
                 }
@@ -382,9 +387,11 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
                         // only active populations are clustered
                         ClusterResult = this.m_CAForSpeciesDifferentation.cluster((Population)this.m_Species.get(i));
                         this.m_Undifferentiated.addPopulation(ClusterResult[0]);
+                        ClusterResult[0].setUseHistory(true);
                         this.m_Undifferentiated.setPopulationSize(this.m_Undifferentiated.getPopulationSize() + ClusterResult[0].size());
                         for (int j = 1; j < ClusterResult.length; j++) {
                             ClusterResult[j].setPopulationSize(ClusterResult[j].size());
+                        	ClusterResult[j].setUseHistory(true);
                             if (ClusterResult.length > 2) ClusterResult[j].m_History = new ArrayList();
                             newSpecies.add(ClusterResult[j]);
                         }
@@ -486,6 +493,7 @@ public class ClusterBasedNichingEA implements InterfacePopulationChangedEventLis
         // output the result
         if (this.m_Debug) System.out.println("-Number of species: " + this.m_Species.size());
         this.m_Population = new Population();
+        m_Population.setUseHistory(true);
         this.m_Population = (Population)this.m_Undifferentiated.clone();
         if (this.m_Debug) System.out.println("initing with " + this.m_Undifferentiated.size());
         for (int i = 0; i < this.m_Species.size(); i++) {