    001package net.sf.cpsolver.exam.criteria;
    002
    003import java.util.Map;
    004import java.util.Set;
    005
    006import net.sf.cpsolver.exam.model.Exam;
    007import net.sf.cpsolver.exam.model.ExamPeriod;
    008import net.sf.cpsolver.exam.model.ExamPlacement;
    009import net.sf.cpsolver.exam.model.ExamStudent;
    010import net.sf.cpsolver.ifs.solver.Solver;
    011import net.sf.cpsolver.ifs.util.DataProperties;
    012
    013/**
    014 * Number of back-to-back student conflicts. I.e., number of cases when
    015 * an exam is attended by a student that attends some other exam at
    016 * the previous {@link ExamPeriod#prev()} or following
    017 * {@link ExamPeriod#next()} period. If
    018 * {@link StudentBackToBackConflicts#isDayBreakBackToBack()} is false, back-to-back conflicts
    019 * are only considered between consecutive periods that are of the same day.
    020 * <br><br>
    021 * Back-to-back student conflict weight can be set by problem property
    022 * Exams.BackToBackConflictWeight, or in the input xml file,
    023 * property backToBackConflictWeight.
    024 *
    025 *
    026 * <br>
    027 *
    028 * @version ExamTT 1.2 (Examination Timetabling)<br>
    029 *          Copyright (C) 2008 - 2012 Tomáš Müller<br>
    030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    032 * <br>
    033 *          This library is free software; you can redistribute it and/or modify
    034 *          it under the terms of the GNU Lesser General Public License as
    035 *          published by the Free Software Foundation; either version 3 of the
    036 *          License, or (at your option) any later version. <br>
    037 * <br>
    038 *          This library is distributed in the hope that it will be useful, but
    039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    041 *          Lesser General Public License for more details. <br>
    042 * <br>
    043 *          You should have received a copy of the GNU Lesser General Public
    044 *          License along with this library; if not see
    045 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    046 */
    047public class StudentBackToBackConflicts extends ExamCriterion {
    048    private boolean iDayBreakBackToBack = false;
    049
    050    @Override
    051    public boolean init(Solver<Exam, ExamPlacement> solver) {
    052        boolean ret = super.init(solver);
    053        iDayBreakBackToBack = solver.getProperties().getPropertyBoolean("Exams.IsDayBreakBackToBack", iDayBreakBackToBack);
    054        return ret;
    055    }
    056
    057    @Override
    058    public String getWeightName() {
    059        return "Exams.BackToBackConflictWeight";
    060    }
    061
    062    @Override
    063    public String getXmlWeightName() {
    064        return "backToBackConflictWeight";
    065    }
    066
    067    @Override
    068    public double getWeightDefault(DataProperties config) {
    069        return 10.0;
    070    }
    071
    072    /**
    073     * True when back-to-back student conflict is to be encountered when a
    074     * student is enrolled into an exam that is on the last period of one day
    075     * and another exam that is on the first period of the consecutive day. It
    076     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
    077     * input xml file, property isDayBreakBackToBack)
    078     */
    079    public boolean isDayBreakBackToBack() {
    080        return iDayBreakBackToBack;
    081    }
    082
    083    /**
    084     * True when back-to-back student conflict is to be encountered when a
    085     * student is enrolled into an exam that is on the last period of one day
    086     * and another exam that is on the first period of the consecutive day. It
    087     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
    088     * input xml file, property isDayBreakBackToBack)
    089     *
    090     */
    091    public void setDayBreakBackToBack(boolean dayBreakBackToBack) {
    092        iDayBreakBackToBack = dayBreakBackToBack;
    093    }
    094
    095    @Override
    096    public void getXmlParameters(Map<String, String> params) {
    097        params.put(getXmlWeightName(), String.valueOf(getWeight()));
    098        params.put("isDayBreakBackToBack", isDayBreakBackToBack() ? "true" : "false");
    099    }
    100
    101    @Override
    102    public void setXmlParameters(Map<String, String> params) {
    103        try {
    104            setWeight(Double.valueOf(params.get(getXmlWeightName())));
    105        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
    106        try {
    107            setDayBreakBackToBack("true".equals(params.get("isDayBreakBackToBack")));
    108        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
    109    }
    110
    111    @Override
    112    public double getValue(ExamPlacement value, Set<ExamPlacement> conflicts) {
    113        Exam exam = value.variable();
    114        int penalty = 0;
    115        for (ExamStudent s : exam.getStudents()) {
    116            if (value.getPeriod().prev() != null) {
    117                if (isDayBreakBackToBack() || value.getPeriod().prev().getDay() == value.getPeriod().getDay()) {
    118                    Set<Exam> exams = s.getExams(value.getPeriod().prev());
    119                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    120                    penalty += nrExams;
    121                }
    122            }
    123            if (value.getPeriod().next() != null) {
    124                if (isDayBreakBackToBack() || value.getPeriod().next().getDay() == value.getPeriod().getDay()) {
    125                    Set<Exam> exams = s.getExams(value.getPeriod().next());
    126                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    127                    penalty += nrExams;
    128                }
    129            }
    130        }
    131        return penalty;
    132    }
    133
    134    @Override
    135    public String getName() {
    136        return "Back-To-Back Conflicts";
    137    }
    138
    139    @Override
    140    public void getInfo(Map<String, String> info) {
    141        if (getValue() != 0.0)
    142            info.put(getName(), sDoubleFormat.format(getValue()));
    143    }
    144
    145    @Override
    146    public String toString() {
    147        return "BTB:" + sDoubleFormat.format(getValue());
    148    }
    149}