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