/*
 *  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;

import java.util.Iterator;

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

/**
 * This criterion terminates if only one single label is left.
 * 
 * @author Sebastian Land, Ingo Mierswa
 */
public class SingleLabelTermination implements Terminator {

    public SingleLabelTermination() {}

    @Override
    public boolean shouldStop(ExampleSet exampleSet, int depth) {
        Attribute label = exampleSet.getAttributes().getLabel();
        Iterator<Example> iterator = exampleSet.iterator();
        if (label != null && iterator.hasNext()) {
            double singleValue = iterator.next().getValue(label);
            while (iterator.hasNext()) {
                if (iterator.next().getValue(label) != singleValue) {
                    return false;
                }
            }
        }
        return true;
    }
}