Repository /Debellor/debellor-1.0.jar:org.debellor.base.evaluator.score.RMSE

/*
 *  Debellor
 *
 *  Copyright (C) 2008-2009 by Marcin Wojnarski
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package org.debellor.base.evaluator.score;

import org.debellor.core.DataObject;
import org.debellor.core.exception.data.DataCastException;


/**
 * Calculates Root Mean Squared Error (RMSE) of numeric decisions predicted by a decision system.
 * 
 * @author Marcin Wojnarski
 *
 */
public class RMSE extends Score {

	private double err;
	private int len;

	
	public RMSE() {
		reset();
	}
	
	@Override
	public void reset() {
		err = 0.0;
		len = 0;
	}

	@Override
	public void add(DataObject target, DataObject prediction) throws DataCastException {
		if(target == null) return;
		double d = target.asNumericFeature().value - prediction.asNumericFeature().value;
		err += d * d;
		len ++;
	}
	
	@Override
	public String report() {
		if(len > 0)
			return "RMSE:   " + result();
		else
			return "No test samples";
	}

	@Override
	public double result() {
		if(len == 0) return 0.0;
		return Math.sqrt(err / len);
	}

}