001package net.sf.cpsolver.exam.criteria;
002
003import java.util.Map;
004import java.util.Set;
005
006import net.sf.cpsolver.exam.model.ExamPlacement;
007import net.sf.cpsolver.ifs.util.DataProperties;
008
009/**
010 * Rotation penalty. I.e., an exam that has been in later period last times tries
011 * to be in an earlier period.
012 * <br><br>
013 * A weight for exam rotation penalty can be set by problem property
014 * Exams.RotationWeight, or in the input xml file, property examRotationWeight.
015 * 
016 * 
017 * <br>
018 * 
019 * @version ExamTT 1.2 (Examination Timetabling)<br>
020 *          Copyright (C) 2008 - 2012 Tomáš Müller<br>
021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
023 * <br>
024 *          This library is free software; you can redistribute it and/or modify
025 *          it under the terms of the GNU Lesser General Public License as
026 *          published by the Free Software Foundation; either version 3 of the
027 *          License, or (at your option) any later version. <br>
028 * <br>
029 *          This library is distributed in the hope that it will be useful, but
030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
032 *          Lesser General Public License for more details. <br>
033 * <br>
034 *          You should have received a copy of the GNU Lesser General Public
035 *          License along with this library; if not see
036 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
037 */
038public class ExamRotationPenalty extends ExamCriterion {
039    private int iAssignedExamsWithAvgPeriod = 0;
040    private double iAveragePeriod = 0.0;
041    
042    @Override
043    public String getWeightName() {
044        return "Exams.RotationWeight";
045    }
046    
047    @Override
048    public String getXmlWeightName() {
049        return "examRotationWeight";
050    }
051    
052    @Override
053    public double getWeightDefault(DataProperties config) {
054        return 0.001;
055    }
056
057    @Override
058    public double getValue(ExamPlacement value, Set<ExamPlacement> conflicts) {
059        if (value.variable().getAveragePeriod() < 0) return 0;
060        return (1 + value.getPeriod().getIndex()) * (1 + value.variable().getAveragePeriod());
061    }
062    
063    @Override
064    public void beforeUnassigned(long iteration, ExamPlacement value) {
065        super.beforeUnassigned(iteration, value);
066        if (value.variable().getAveragePeriod() >= 0) {
067            iAssignedExamsWithAvgPeriod --;
068            iAveragePeriod -= value.variable().getAveragePeriod();
069        }
070    }
071    
072    @Override
073    public void afterAssigned(long iteration, ExamPlacement value) {
074        super.afterAssigned(iteration, value);
075        if (value.variable().getAveragePeriod() >= 0) {
076            iAssignedExamsWithAvgPeriod ++;
077            iAveragePeriod += value.variable().getAveragePeriod();
078        }
079    }
080    
081    public int nrAssignedExamsWithAvgPeriod() {
082        return iAssignedExamsWithAvgPeriod;
083    }
084    
085    public double averagePeriod() {
086        return iAveragePeriod / iAssignedExamsWithAvgPeriod;
087    }
088    
089    @Override
090    public void getInfo(Map<String, String> info) {
091        if (getValue() != 0.0) {
092            info.put(getName(), sDoubleFormat.format(Math.sqrt(getValue() / iAssignedExamsWithAvgPeriod) - 1));
093        }
094    }
095    
096    @Override
097    public String toString() {
098        return "@P:" + sDoubleFormat.format((Math.sqrt(getValue() / iAssignedExamsWithAvgPeriod) - 1));
099    }
100}