    001package org.cpsolver.coursett.sectioning;
    002
    003import java.util.ArrayList;
    004import java.util.Collection;
    005import java.util.Comparator;
    006import java.util.HashSet;
    007import java.util.List;
    008import java.util.Set;
    009import java.util.TreeSet;
    010
    011import org.cpsolver.coursett.constraint.JenrlConstraint;
    012import org.cpsolver.coursett.criteria.StudentConflict;
    013import org.cpsolver.coursett.custom.DeterministicStudentSectioning.DeterministicInitialSectioning;
    014import org.cpsolver.coursett.model.Configuration;
    015import org.cpsolver.coursett.model.DefaultStudentSectioning;
    016import org.cpsolver.coursett.model.InitialSectioning.Group;
    017import org.cpsolver.coursett.model.Lecture;
    018import org.cpsolver.coursett.model.Placement;
    019import org.cpsolver.coursett.model.Student;
    020import org.cpsolver.coursett.model.TimetableModel;
    021import org.cpsolver.coursett.sectioning.SctModel.SctSolution;
    022import org.cpsolver.ifs.assignment.Assignment;
    023import org.cpsolver.ifs.criteria.Criterion;
    024import org.cpsolver.ifs.model.InfoProvider;
    025import org.cpsolver.ifs.solution.Solution;
    026import org.cpsolver.ifs.termination.TerminationCondition;
    027import org.cpsolver.ifs.util.Progress;
    028
    029/**
    030 *
    031 * Student sectioning implementation based on branch &amp; bound. This sectioning takes
    032 * each offering one by one and it is using a branch &amp; bound algorithm to find
    033 * the best possible enrollment of all students into the given course. The sectioning
    034 * considers both student conflict weights and student groups.
    035 *
    036 * @author  Tomáš Müller
    037 * @version CourseTT 1.3 (University Course Timetabling)<br>
    038 *          Copyright (C) 2017 Tomáš Müller<br>
    039 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    040 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    041 * <br>
    042 *          This library is free software; you can redistribute it and/or modify
    043 *          it under the terms of the GNU Lesser General Public License as
    044 *          published by the Free Software Foundation; either version 3 of the
    045 *          License, or (at your option) any later version. <br>
    046 * <br>
    047 *          This library is distributed in the hope that it will be useful, but
    048 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    049 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    050 *          Lesser General Public License for more details. <br>
    051 * <br>
    052 *          You should have received a copy of the GNU Lesser General Public
    053 *          License along with this library; if not see
    054 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    055 */
    056public class SctSectioning extends DefaultStudentSectioning implements InfoProvider<Lecture, Placement> {
    057    private boolean iUseCriteria = true;
    058    private int iNrRounds = 3;
    059    private List<StudentConflict> iStudentConflictCriteria = null;
    060
    061    public SctSectioning(TimetableModel model) {
    062        super(model);
    063        iUseCriteria = model.getProperties().getPropertyBoolean("SctSectioning.UseCriteria", true);
    064        iNrRounds = model.getProperties().getPropertyInt("SctSectioning.NrRounds", 3);
    065    }
    066
    067    @Override
    068    public boolean hasFinalSectioning() {
    069        return true;
    070    }
    071
    072    /**
    073     * List of student conflict criteria
    074     */
    075    protected List<StudentConflict> getStudentConflictCriteria() {
    076        if (!iUseCriteria) return null;
    077        if (iStudentConflictCriteria == null && iModel != null) {
    078            iStudentConflictCriteria = new ArrayList<StudentConflict>();
    079            for (Criterion<Lecture, Placement> criterion: iModel.getCriteria())
    080                if (criterion instanceof StudentConflict)
    081                    iStudentConflictCriteria.add((StudentConflict)criterion);
    082        }
    083        return iStudentConflictCriteria;
    084    }
    085
    086    /**
    087     * Student conflict weight for the given solution
    088     */
    089    protected double value(Solution<Lecture, Placement> solution) {
    090        List<StudentConflict> criteria = getStudentConflictCriteria();
    091
    092        if (criteria == null) {
    093            double value = 0.0;
    094            for (JenrlConstraint constraint: ((TimetableModel)solution.getModel()).getJenrlConstraints()) {
    095                if (constraint.isInConflict(solution.getAssignment())) value += constraint.jenrl();
    096            }
    097            return value;
    098        }
    099
    100        double value = 0.0;
    101        for (StudentConflict criterion: criteria)
    102            value += criterion.getWeightedValue(solution.getAssignment());
    103        return value;
    104    }
    105
    106    @Override
    107    public void switchStudents(Solution<Lecture, Placement> solution, TerminationCondition<Lecture, Placement> termination) {
    108        getProgress().setStatus("Student Sectioning...");
    109        getProgress().info("Student Conflicts: " + sDF2.format(value(solution)) + " (group: " + sDF2.format(StudentSwapSectioning.gp(solution)) + "%)");
    110
    111        for (int i = 1; i <= iNrRounds; i++) {
    112            getProgress().setPhase("Swapping students [" + i + "]...", iModel.variables().size());
    113            Set<Long> offeringIds = new HashSet<Long>();
    114            for (Lecture lecture: iModel.variables()) {
    115                getProgress().incProgress();
    116                if (lecture.students().isEmpty() || lecture.isSingleSection()) continue;
    117                if (termination != null && !termination.canContinue(solution)) return;
    118                if (offeringIds.add(lecture.getConfiguration().getOfferingId())) {
    119                    SctModel model = new SctModel(iModel, solution.getAssignment());
    120                    model.setConfiguration(lecture.getConfiguration());
    121                    SctSolution s1 = model.currentSolution();
    122                    SctSolution s2 = model.computeSolution();
    123                    if (model.isTimeOutReached())
    124                        getProgress().info("Timeout reached for " + lecture.getName());
    125                    if (s2.isBetter(s1)) {
    126                        model.unassign();
    127                        model.assign(s2);
    128                        getProgress().info("Student Conflicts: " + sDF2.format(value(solution)) + " (group: " + sDF2.format(StudentSwapSectioning.gp(solution)) + "%)");
    129                    }
    130                }
    131            }
    132            getProgress().info("Student Conflicts: " + sDF2.format(value(solution)) + " (group: " + sDF2.format(StudentSwapSectioning.gp(solution)) + "%)");
    133        }
    134    }
    135
    136    @Override
    137    public void resection(Assignment<Lecture, Placement> assignment, Lecture lecture, boolean recursive, boolean configAsWell) {
    138        SctModel model = new SctModel(iModel, assignment);
    139        model.setConfiguration(lecture.getConfiguration());
    140        SctSolution s1 = model.currentSolution();
    141        SctSolution s2 = model.computeSolution();
    142        if (s2.isBetter(s1)) {
    143            model.unassign();
    144            model.assign(s2);
    145        }
    146    }
    147
    148    protected boolean hasStudentGroups(Collection<Student> students) {
    149        for (Student student: students)
    150            if (!student.getGroups().isEmpty()) return true;
    151        return false;
    152    }
    153
    154    @Override
    155    protected Group[] studentsToConfigurations(Long offeringId, Collection<Student> students, Collection<Configuration> configurations) {
    156        if (hasStudentGroups(students)) {
    157            GroupBasedInitialSectioning sect = new GroupBasedInitialSectioning(getProgress(), offeringId, configurations, students);
    158            return sect.getGroups();
    159        } else {
    160            return super.studentsToConfigurations(offeringId, students, configurations);
    161        }
    162    }
    163
    164    @Override
    165    protected Group[] studentsToLectures(Long offeringId, Collection<Student> students, Collection<Lecture> lectures) {
    166        if (hasStudentGroups(students)) {
    167            Set<Lecture> sortedLectures = new TreeSet<Lecture>(new Comparator<Lecture>() {
    168                @Override
    169                public int compare(Lecture l1, Lecture l2) {
    170                    return l1.getClassId().compareTo(l2.getClassId());
    171                }
    172            });
    173            sortedLectures.addAll(lectures);
    174            GroupBasedInitialSectioning sect = new GroupBasedInitialSectioning(getProgress(), offeringId, sortedLectures, students);
    175            return sect.getGroups();
    176        } else {
    177            return super.studentsToLectures(offeringId, students, lectures);
    178        }
    179    }
    180
    181    protected static class GroupBasedInitialSectioning extends DeterministicInitialSectioning {
    182        public GroupBasedInitialSectioning(Progress progress, Long offeringId, Collection<?> lectureOrConfigurations, Collection<Student> students) {
    183            super(progress, offeringId, lectureOrConfigurations, students);
    184        }
    185
    186        @Override
    187        public int compare(Student s1, Student s2) {
    188            int cmp = s1.getGroupNames().compareToIgnoreCase(s2.getGroupNames());
    189            if (cmp != 0) return cmp;
    190            return super.compare(s1, s2);
    191        }
    192    }
    193}