/**
 * Copyright (C) 2001-2017 by RapidMiner and the contributors
 * 
 * Complete list of developers available at our web site:
 * 
 * http://rapidminer.com
 * 
 * This program is free software: you can redistribute it and/or modify it under the terms of the
 * GNU Affero 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
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License along with this program.
 * If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.operator.learner.subgroups.utility;

import com.rapidminer.operator.learner.subgroups.hypothesis.Hypothesis;
import com.rapidminer.operator.learner.subgroups.hypothesis.Rule;


/**
 * Calculates accuracy.
 * 
 * @author Tobias Malbrecht
 */
public class Accuracy extends UtilityFunction {

	private static final long serialVersionUID = 1L;

	public Accuracy(double totalWeight, double totalPositiveWeight) {
		super(totalWeight, totalPositiveWeight);
	}

	@Override
	public double utility(Rule rule) {
		double totalPredictionWeight = rule.predictsPositive() ? totalPositiveWeight : totalNegativeWeight;
		return (totalWeight - totalPredictionWeight - rule.getCoveredWeight() + 2 * rule.getPredictionWeight())
				/ totalWeight;
	}

	@Override
	public double optimisticEstimate(Hypothesis hypothesis) {
		return 1.0d;
	}

	@Override
	public String getName() {
		return "Accuracy";
	}

	@Override
	public String getAbbreviation() {
		return "Acc";
	}
}