/**
 * 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.validation.significance;

import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.UserError;
import com.rapidminer.operator.ValueDouble;
import com.rapidminer.operator.performance.PerformanceCriterion;
import com.rapidminer.operator.performance.PerformanceVector;
import com.rapidminer.tools.math.AnovaCalculator;
import com.rapidminer.tools.math.SignificanceCalculationException;
import com.rapidminer.tools.math.SignificanceTestResult;


/**
 * Determines if the null hypothesis (all actual mean values are the same) holds for the input
 * performance vectors. This operator uses an ANalysis Of VAriances approach to determine
 * probability that the null hypothesis is wrong.
 * 
 * @author Ingo Mierswa
 */
public class AnovaSignificanceTestOperator extends SignificanceTestOperator {

	private double probability;

	public AnovaSignificanceTestOperator(OperatorDescription description) {
		super(description);

		addValue(new ValueDouble("probability", "The probability for not differ significantly of the last test.") {

			@Override
			public double getDoubleValue() {
				return probability;
			}
		});
	}

	@Override
	public SignificanceTestResult performSignificanceTest(PerformanceVector[] allVectors, double alpha)
			throws OperatorException {
		AnovaCalculator calculator = new AnovaCalculator();
		calculator.setAlpha(alpha);

		for (int i = 0; i < allVectors.length; i++) {
			PerformanceCriterion pc = allVectors[i].getMainCriterion();
			calculator.addGroup(pc.getAverageCount(), pc.getAverage(), pc.getVariance());
		}

		try {
			SignificanceTestResult testResult = calculator.performSignificanceTest();
			this.probability = testResult.getProbability();
			return testResult;
		} catch (SignificanceCalculationException e) {
			throw new UserError(this, 920, e.getMessage());
		}
	}

	@Override
	public int getMinSize() {
		return 2;
	}

	@Override
	public int getMaxSize() {
		return Integer.MAX_VALUE;
	}
}