/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.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.tree.criterions;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorException;

/**
 * The criterion for a splitted example set. Possible implementations are
 * for example accuracy or information gain.
 * 
 * @author Sebastian Land, Ingo Mierswa
 */
public interface Criterion {

    public double getNominalBenefit(ExampleSet exampleSet, Attribute attribute) throws OperatorException;
    
    public double getNumericalBenefit(ExampleSet exampleSet, Attribute attribute, double splitValue) throws OperatorException;
    
    
    public boolean supportsIncrementalCalculation();
    
    public void startIncrementalCalculation(ExampleSet exampleSet) throws OperatorException;
    
    public void swapExample(Example example);
    
	public double getIncrementalBenefit();

	/**
	 * This method will return the calculated benefit if the weights would have distributed
	 * over the labels as given. The first index specifies the split fraction, the second index the label.
	 * Henve the first index is always between 0 and 1 included for numerical splits, since only two sides
	 * can occur there. For splits on nominal attributes, the number of split sides is determined by the number of possible values.
	 */
	public double getBenefit(double[][] weightCounts);
}