/**
* Genetic Algorithm
*
* @param populationSize The size of the new ArrayList
* @param mutationProbability The number of the probability we want.
* @param minimumFitness THe minimumFitness score of our generated Chrome object.
* @param maximumSteps The maximum steps for which the algorithm will run for.
* @return Returns a new Chrome object.
*/
public Chrome geneticAlgorithm(
int populationSize, double mutationProbability, int minimumFitness, int maximumSteps) {
initializePopulation(populationSize);
Random r = new Random(System.currentTimeMillis());
for (int step = 0; step < maximumSteps; step++) {
ArrayList<Chrome> newPopulation = new ArrayList<Chrome>();
for (int i = 0; i < populationSize; i++) {
int xIndex = this.mFitnessBounds.get(r.nextInt(this.mFitnessBounds.size()));
Chrome x = this.mPopulation.get(xIndex);
int yIndex = this.mFitnessBounds.get(r.nextInt(this.mFitnessBounds.size()));
while (yIndex == xIndex) {
yIndex = this.mFitnessBounds.get(r.nextInt(this.mFitnessBounds.size()));
}
Chrome y = this.mPopulation.get(yIndex);
Chrome child = this.reproduce(x, y);
if (r.nextDouble() < mutationProbability) {
child.mutate(Utilities.createDayTimeSlots(mSlots));
}
newPopulation.add(child);
}
this.mPopulation = new ArrayList<Chrome>(newPopulation);
Collections.sort(this.mPopulation, Collections.reverseOrder());
if (this.mPopulation.get(0).getScore() >= minimumFitness) {
System.out.println("Finished after " + step + " steps...");
return this.mPopulation.get(0);
}
// We update the fitnessBounds arrayList
this.updateFitnessBounds();
}
System.out.println("Finished after " + maximumSteps + " steps...");
return this.mPopulation.get(0);
}
/**
* Reproduce method that generates a new <code>Chrome</code> object from the two given ones.
*
* @param x First <code>Chrome</code> object
* @param y Second <code>Chrome</code> object
* @return The <code>Chrome</code> object which was created from <code>x</code> and <code>y</code>
*/
public Chrome reproduce(Chrome x, Chrome y) {
Random r = new Random();
CustomMap childGenes = new CustomMap();
// Randomly choose the intersection point
int intersectionPoint = r.nextInt(x.getSize());
for (int i = 0; i < intersectionPoint; i++) {
childGenes.addKey(x.getMapKey(i));
childGenes.addValue(x.getMapValue(i));
}
for (int i = intersectionPoint; i < x.getSize(); i++) {
childGenes.addKey(y.getMapKey(i));
childGenes.addValue(y.getMapValue(i));
}
return new Chrome(childGenes, mRooms, mInstructors, mSlots);
}