    001package org.cpsolver.exam.criteria;
    002
    003import java.util.Collection;
    004import java.util.Map;
    005import java.util.Set;
    006
    007import org.cpsolver.exam.model.Exam;
    008import org.cpsolver.exam.model.ExamModel;
    009import org.cpsolver.exam.model.ExamPeriod;
    010import org.cpsolver.exam.model.ExamPlacement;
    011import org.cpsolver.exam.model.ExamStudent;
    012import org.cpsolver.ifs.assignment.Assignment;
    013import org.cpsolver.ifs.util.DataProperties;
    014
    015
    016/**
    017 * Number of back-to-back student conflicts. I.e., number of cases when
    018 * an exam is attended by a student that attends some other exam at
    019 * the previous {@link ExamPeriod#prev()} or following
    020 * {@link ExamPeriod#next()} period. If
    021 * {@link StudentBackToBackConflicts#isDayBreakBackToBack()} is false, back-to-back conflicts
    022 * are only considered between consecutive periods that are of the same day.
    023 * <br><br>
    024 * Back-to-back student conflict weight can be set by problem property
    025 * Exams.BackToBackConflictWeight, or in the input xml file,
    026 * property backToBackConflictWeight.
    027 *
    028 *
    029 * <br>
    030 *
    031 * @author  Tomáš Müller
    032 * @version ExamTT 1.3 (Examination Timetabling)<br>
    033 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    034 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    035 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    036 * <br>
    037 *          This library is free software; you can redistribute it and/or modify
    038 *          it under the terms of the GNU Lesser General Public License as
    039 *          published by the Free Software Foundation; either version 3 of the
    040 *          License, or (at your option) any later version. <br>
    041 * <br>
    042 *          This library is distributed in the hope that it will be useful, but
    043 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    044 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    045 *          Lesser General Public License for more details. <br>
    046 * <br>
    047 *          You should have received a copy of the GNU Lesser General Public
    048 *          License along with this library; if not see
    049 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    050 */
    051public class StudentBackToBackConflicts extends ExamCriterion {
    052    private boolean iDayBreakBackToBack = false;
    053
    054    @Override
    055    public void configure(DataProperties properties) {
    056        super.configure(properties);
    057        iDayBreakBackToBack = properties.getPropertyBoolean("Exams.IsDayBreakBackToBack", iDayBreakBackToBack);
    058    }
    059
    060    @Override
    061    public String getWeightName() {
    062        return "Exams.BackToBackConflictWeight";
    063    }
    064
    065    @Override
    066    public String getXmlWeightName() {
    067        return "backToBackConflictWeight";
    068    }
    069
    070    @Override
    071    public double getWeightDefault(DataProperties config) {
    072        return 10.0;
    073    }
    074
    075    /**
    076     * True when back-to-back student conflict is to be encountered when a
    077     * student is enrolled into an exam that is on the last period of one day
    078     * and another exam that is on the first period of the consecutive day. It
    079     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
    080     * input xml file, property isDayBreakBackToBack)
    081     * @return true if last exam on one day is back-to-back to the first exam of the following day
    082     */
    083    public boolean isDayBreakBackToBack() {
    084        return iDayBreakBackToBack;
    085    }
    086
    087    /**
    088     * True when back-to-back student conflict is to be encountered when a
    089     * student is enrolled into an exam that is on the last period of one day
    090     * and another exam that is on the first period of the consecutive day. It
    091     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
    092     * input xml file, property isDayBreakBackToBack)
    093     * @param dayBreakBackToBack true if last exam on one day is back-to-back to the first exam of the following day
    094     *
    095     */
    096    public void setDayBreakBackToBack(boolean dayBreakBackToBack) {
    097        iDayBreakBackToBack = dayBreakBackToBack;
    098    }
    099
    100    @Override
    101    public void getXmlParameters(Map<String, String> params) {
    102        params.put(getXmlWeightName(), String.valueOf(getWeight()));
    103        params.put("isDayBreakBackToBack", isDayBreakBackToBack() ? "true" : "false");
    104    }
    105
    106    @Override
    107    public void setXmlParameters(Map<String, String> params) {
    108        try {
    109            setWeight(Double.valueOf(params.get(getXmlWeightName())));
    110        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
    111        try {
    112            setDayBreakBackToBack("true".equals(params.get("isDayBreakBackToBack")));
    113        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
    114    }
    115
    116    @Override
    117    public double getValue(Assignment<Exam, ExamPlacement> assignment, ExamPlacement value, Set<ExamPlacement> conflicts) {
    118        Exam exam = value.variable();
    119        int penalty = 0;
    120        ExamPeriod period = value.getPeriod();
    121        Map<ExamStudent, Set<Exam>> prev = (period.prev() != null && (isDayBreakBackToBack() || period.prev().getDay() == period.getDay()) ? ((ExamModel)getModel()).getStudentsOfPeriod(assignment, period.prev()) : null);
    122        Map<ExamStudent, Set<Exam>> next = (period.next() != null && (isDayBreakBackToBack() || period.next().getDay() == period.getDay()) ? ((ExamModel)getModel()).getStudentsOfPeriod(assignment, period.next()) : null);
    123        for (ExamStudent s : exam.getStudents()) {
    124            if (prev != null) {
    125                Set<Exam> exams = prev.get(s);
    126                if (exams != null) {
    127                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    128                    penalty += nrExams;
    129                }
    130            }
    131            if (next != null) {
    132                Set<Exam> exams = next.get(s);
    133                if (exams != null) {
    134                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    135                    penalty += nrExams;
    136                }
    137            }
    138        }
    139        /*
    140        for (ExamStudent s : exam.getStudents()) {
    141            if (period.prev() != null) {
    142                if (isDayBreakBackToBack() || period.prev().getDay() == period.getDay()) {
    143                    Set<Exam> exams = s.getExams(assignment, period.prev());
    144                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    145                    penalty += nrExams;
    146                }
    147            }
    148            if (period.next() != null) {
    149                if (isDayBreakBackToBack() || period.next().getDay() == period.getDay()) {
    150                    Set<Exam> exams = s.getExams(assignment, period.next());
    151                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
    152                    penalty += nrExams;
    153                }
    154            }
    155        }
    156        */
    157        return penalty;
    158    }
    159
    160    @Override
    161    public double getValue(Assignment<Exam, ExamPlacement> assignment, Collection<Exam> variables) {
    162        return super.getValue(assignment, variables) / 2.0;
    163    }
    164
    165    @Override
    166    public String getName() {
    167        return "Back-To-Back Conflicts";
    168    }
    169
    170    @Override
    171    public void getInfo(Assignment<Exam, ExamPlacement> assignment, Map<String, String> info) {
    172        if (getValue(assignment) != 0.0)
    173            info.put(getName(), sDoubleFormat.format(getValue(assignment)));
    174    }
    175
    176    @Override
    177    public String toString(Assignment<Exam, ExamPlacement> assignment) {
    178        return "BTB:" + sDoubleFormat.format(getValue(assignment));
    179    }
    180}