/*
 * Copyright 2007-2013
 * Licensed under GNU Lesser General Public License
 * 
 * This file is part of EpochX
 * 
 * EpochX is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * EpochX is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with EpochX. If not, see <http://www.gnu.org/licenses/>.
 * 
 * The latest version is available from: http://www.epochx.org
 */

package org.epochx.event.stat;

import java.util.HashSet;

import org.epochx.Fitness;
import org.epochx.event.GenerationEvent.EndGeneration;

/**
 * Stats representing the number of different fitness values in a generation.
 */
public class GenerationFitnessDiversity extends AbstractStat<EndGeneration> {

	/**
	 * The number of different fitness values.
	 */
	private int diversity = 0;

	/**
	 * Constructs a <code>GenerationFitnessDiversity</code>.
	 */
	public GenerationFitnessDiversity() {
		super(GenerationFitnesses.class);
	}

	/**
	 * Computes the number of different fitness values.
	 * 
	 * @param event the <code>EndGeneration</code> event object.
	 */
	@Override
	public void refresh(EndGeneration event) {
		Fitness[] fitnesses = AbstractStat.get(GenerationFitnesses.class).getFitnesses();
		HashSet<String> unique = new HashSet<String>();

		for (Fitness fitness: fitnesses) {
			unique.add(fitness.toString());
		}

		diversity = unique.size();
	}

	/**
	 * Returns a string representation of the number of different fitness vaues.
	 * 
	 * @return a string representation of the number of different fitness vaues.
	 */
	@Override
	public String toString() {
		return Integer.toString(diversity);
	}

}