aco/strategy/as/ASPheromoneStrategy.java

   1 package aco.strategy.as;
   2
   3 import aco.ant.*;
   4 import aco.strategy.*;
   5 import aco.mediator.*;
   6
   7 public class ASPheromoneStrategy
   8   extends PheromoneStrategy {
   9
  10   public ASPheromoneStrategy(ACOMediator acom) {
  11     super(acom);
  12   }
  13
  14   public void pheromoneUpdate(Ant[] ants) {
  15     this.evaporate();
  16
  17     for (Ant ant : ants) {
  18       this.depositPheromone(ant);
  19     }
  20
  21     acom.computeChoiceInformation();
  22   }
  23
  24   protected void depositPheromone(Ant ant) {
  25     double dt = 1.0/ant.getTourLength();
  26     int j = 0;
  27     int l = 0;
  28     for (int i = 0; i < acom.getNumOfCities(); i++) {
  29       j = ant.getTour(i);
  30       l = ant.getTour(i+1);
  31       /* setPheromone will update j,l and l,j */
  32       acom.setPheromone( j, l, (acom.getPheromone(j,l) + dt) );
  33     }
  34   }
  35
  36   protected void evaporate() {
  37     for (int i = 0; i < acom.getNumOfCities(); i++) {
  38       for (int j = 0; j < acom.getNumOfCities(); j++) {
  39         acom.setPheromone(i, j,
  40             (1.0 - acom.getRoh()) * acom.getPheromone(i, j) );
  41       }
  42     }
  43   }
  44
  45 }