    001package org.cpsolver.exam.criteria;
    002
    003import java.util.Map;
    004import java.util.Set;
    005
    006import org.cpsolver.exam.model.Exam;
    007import org.cpsolver.exam.model.ExamPlacement;
    008import org.cpsolver.ifs.assignment.Assignment;
    009import org.cpsolver.ifs.util.DataProperties;
    010
    011
    012/**
    013 * Rotation penalty. I.e., an exam that has been in later period last times tries
    014 * to be in an earlier period.
    015 * <br><br>
    016 * A weight for exam rotation penalty can be set by problem property
    017 * Exams.RotationWeight, or in the input xml file, property examRotationWeight.
    018 *
    019 *
    020 * <br>
    021 *
    022 * @version ExamTT 1.3 (Examination Timetabling)<br>
    023 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    024 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    025 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    026 * <br>
    027 *          This library is free software; you can redistribute it and/or modify
    028 *          it under the terms of the GNU Lesser General Public License as
    029 *          published by the Free Software Foundation; either version 3 of the
    030 *          License, or (at your option) any later version. <br>
    031 * <br>
    032 *          This library is distributed in the hope that it will be useful, but
    033 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    034 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    035 *          Lesser General Public License for more details. <br>
    036 * <br>
    037 *          You should have received a copy of the GNU Lesser General Public
    038 *          License along with this library; if not see
    039 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    040 */
    041public class ExamRotationPenalty extends ExamCriterion {
    042
    043    @Override
    044    public ValueContext createAssignmentContext(Assignment<Exam, ExamPlacement> assignment) {
    045        return new RotationContext(assignment);
    046    }
    047
    048    @Override
    049    public String getWeightName() {
    050        return "Exams.RotationWeight";
    051    }
    052
    053    @Override
    054    public String getXmlWeightName() {
    055        return "examRotationWeight";
    056    }
    057
    058    @Override
    059    public double getWeightDefault(DataProperties config) {
    060        return 0.001;
    061    }
    062
    063    @Override
    064    public double getValue(Assignment<Exam, ExamPlacement> assignment, ExamPlacement value, Set<ExamPlacement> conflicts) {
    065        if (value.variable().getAveragePeriod() < 0) return 0;
    066        return (1 + value.getPeriod().getIndex()) * (1 + value.variable().getAveragePeriod());
    067    }
    068
    069    public int nrAssignedExamsWithAvgPeriod(Assignment<Exam, ExamPlacement> assignment) {
    070        return ((RotationContext)getContext(assignment)).nrAssignedExamsWithAvgPeriod();
    071    }
    072
    073    public double averagePeriod(Assignment<Exam, ExamPlacement> assignment) {
    074        return ((RotationContext)getContext(assignment)).averagePeriod();
    075    }
    076
    077    @Override
    078    public void getInfo(Assignment<Exam, ExamPlacement> assignment, Map<String, String> info) {
    079        if (getValue(assignment) != 0.0) {
    080            info.put(getName(), sDoubleFormat.format(Math.sqrt(getValue(assignment) / nrAssignedExamsWithAvgPeriod(assignment)) - 1));
    081        }
    082    }
    083
    084    @Override
    085    public String toString(Assignment<Exam, ExamPlacement> assignment) {
    086        return "@P:" + sDoubleFormat.format((Math.sqrt(getValue(assignment) / nrAssignedExamsWithAvgPeriod(assignment)) - 1));
    087    }
    088
    089    protected class RotationContext extends ValueContext {
    090        private int iAssignedExamsWithAvgPeriod = 0;
    091        private double iAveragePeriod = 0.0;
    092
    093        public RotationContext(Assignment<Exam, ExamPlacement> assignment) {
    094            super(assignment);
    095            for (Exam exam: getModel().variables())
    096                if (exam.getAveragePeriod() > 0) {
    097                    ExamPlacement placement = assignment.getValue(exam);
    098                    if (placement != null) {
    099                        iAssignedExamsWithAvgPeriod ++;
    100                        iAveragePeriod += exam.getAveragePeriod();
    101                    }
    102                }
    103        }
    104
    105        @Override
    106        public void assigned(Assignment<Exam, ExamPlacement> assignment, ExamPlacement value) {
    107            super.assigned(assignment, value);
    108            if (value.variable().getAveragePeriod() >= 0) {
    109                iAssignedExamsWithAvgPeriod ++;
    110                iAveragePeriod += value.variable().getAveragePeriod();
    111            }
    112        }
    113
    114        @Override
    115        public void unassigned(Assignment<Exam, ExamPlacement> assignment, ExamPlacement value) {
    116            super.unassigned(assignment, value);
    117            if (value.variable().getAveragePeriod() >= 0) {
    118                iAssignedExamsWithAvgPeriod --;
    119                iAveragePeriod -= value.variable().getAveragePeriod();
    120            }
    121        }
    122
    123        public int nrAssignedExamsWithAvgPeriod() {
    124            return iAssignedExamsWithAvgPeriod;
    125        }
    126
    127        public double averagePeriod() {
    128            return iAveragePeriod / iAssignedExamsWithAvgPeriod;
    129        }
    130    }
    131}