    001package org.cpsolver.coursett.custom;
    002
    003import java.util.ArrayList;
    004import java.util.Collection;
    005import java.util.Comparator;
    006import java.util.Iterator;
    007import java.util.Set;
    008import java.util.TreeSet;
    009
    010import org.cpsolver.coursett.model.Configuration;
    011import org.cpsolver.coursett.model.DefaultStudentSectioning;
    012import org.cpsolver.coursett.model.InitialSectioning;
    013import org.cpsolver.coursett.model.Lecture;
    014import org.cpsolver.coursett.model.Placement;
    015import org.cpsolver.coursett.model.Student;
    016import org.cpsolver.coursett.model.StudentSectioning;
    017import org.cpsolver.coursett.model.TimetableModel;
    018import org.cpsolver.coursett.model.InitialSectioning.Group;
    019import org.cpsolver.ifs.assignment.Assignment;
    020import org.cpsolver.ifs.solution.Solution;
    021import org.cpsolver.ifs.termination.TerminationCondition;
    022import org.cpsolver.ifs.util.Progress;
    023
    024
    025/**
    026 * Deterministic implementation of the initial student sectioning. This class assign students to groups in
    027 * a deterministic way. Students are ordered by their academic information (curriculum) and unique ids and
    028 * assigned in this order to the first available group (configuration or lecture). See {@link StudentSectioning}
    029 * and {@link DefaultStudentSectioning} for more details about sectioning students during course timetabling.
    030 * <br><br>
    031 * This deterministic sectioning can be enabled by setting the following parameter:<pre>
    032 * <code>StudentSectioning.Class=org.cpsolver.coursett.custom.DeterministicStudentSectioning</code>
    033 * </pre>
    034 *
    035 * @version CourseTT 1.3 (University Course Timetabling)<br>
    036 *          Copyright (C) 2014 Tomáš Müller<br>
    037 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    038 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    039 *          This customization has been implemented for <a href='http://www.agh.pl'>AGH, Poland</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 DeterministicStudentSectioning extends DefaultStudentSectioning {
    056    public DeterministicStudentSectioning(TimetableModel model) {
    057        super(model);
    058    }
    059
    060    @Override
    061    protected Group[] studentsToConfigurations(Long offeringId, Collection<Student> students, Collection<Configuration> configurations) {
    062        DeterministicInitialSectioning sect = new DeterministicInitialSectioning(getProgress(), offeringId, configurations, students);
    063        return sect.getGroups();
    064    }
    065
    066    @Override
    067    protected Group[] studentsToLectures(Long offeringId, Collection<Student> students, Collection<Lecture> lectures) {
    068        Set<Lecture> sortedLectures = new TreeSet<Lecture>(new Comparator<Lecture>() {
    069            @Override
    070            public int compare(Lecture l1, Lecture l2) {
    071                return l1.getClassId().compareTo(l2.getClassId());
    072            }
    073        });
    074        sortedLectures.addAll(lectures);
    075        DeterministicInitialSectioning sect = new DeterministicInitialSectioning(getProgress(), offeringId, sortedLectures, students);
    076        return sect.getGroups();
    077    }
    078
    079    /**
    080     * No re-sectioning (final sectioning) during deterministic student sectioning.
    081     */
    082    @Override
    083    public boolean hasFinalSectioning() {
    084        return false;
    085    }
    086
    087    /**
    088     * No re-sectioning (final sectioning) during deterministic student sectioning.
    089     */
    090    @Override
    091    public void switchStudents(Solution<Lecture, Placement> solution, TerminationCondition<Lecture, Placement> termination) {
    092    }
    093
    094    /**
    095     * No re-sectioning (final sectioning) during deterministic student sectioning.
    096     */
    097    @Override
    098    public void resection(Assignment<Lecture, Placement> assignment, Lecture lecture, boolean recursive, boolean configAsWell) {
    099    }
    100
    101    /**
    102     * Assign students to groups in a deterministic way, i.e., first student to first available group etc.
    103     * @author Tomáš Müller
    104     */
    105    public static class DeterministicInitialSectioning extends InitialSectioning implements Comparator<Student> {
    106
    107        public DeterministicInitialSectioning(Progress progress, Long offeringId, Collection<?> lectureOrConfigurations, Collection<Student> students) {
    108            super(progress, offeringId, lectureOrConfigurations, students);
    109
    110            // Sort students by their curriculum information first
    111            iStudents = new TreeSet<Student>(this); iStudents.addAll(students);
    112        }
    113
    114        @Override
    115        protected void tweakSizes(double total) {
    116            double studentsWeight = 0;
    117            for (Student s : iStudents) {
    118                studentsWeight += s.getOfferingWeight(iOfferingId);
    119            }
    120
    121            // if there is not enough space for the given students
    122            if (studentsWeight > total) {
    123                if (total == 0) {
    124                    // all limits are zero -> spread students equally
    125                    for (int idx = 0; idx < iGroups.length; idx++)
    126                        iGroups[idx].setMaxSize(total / iGroups.length);
    127                } else {
    128                    // enlarge sections proportionally
    129                    double factor = studentsWeight / total;
    130                    for (int idx = 0; idx < iGroups.length; idx++) {
    131                        iGroups[idx].setMaxSize(factor * iGroups[idx].getMaxSize());
    132                        iGroups[idx].setMinSize(Math.min(iGroups[idx].getMinSize(), 0.9 * iGroups[idx].getMaxSize()));
    133                   }
    134                }
    135            }
    136        }
    137
    138        @Override
    139        public Group[] getGroups() {
    140            // Assign already enrolled students first
    141            students: for (Iterator<Student> i = iStudents.iterator(); i.hasNext();) {
    142                Student student = i.next();
    143                for (int idx = 0; idx < iGroups.length; idx++) {
    144                    if (iGroups[idx].isEnrolled(student)) {
    145                        iGroups[idx].addStudent(student);
    146                        i.remove();
    147                        continue students;
    148                    }
    149                }
    150            }
    151
    152            // For all other (not enrolled) students
    153            students: for (Student student : iStudents) {
    154                double studentWeight = student.getOfferingWeight(iOfferingId);
    155
    156                // enroll into first available group with enough space
    157                for (int idx = 0; idx < iGroups.length; idx++) {
    158                    Group g = iGroups[idx];
    159                    if (!g.canEnroll(student) || g.size() >= g.getMaxSize()) continue;
    160                    // group found -> enroll and continue with the next student
    161                    g.addStudent(student);
    162                    continue students;
    163                }
    164
    165                // disobey max size, but prefer sections with smallest excess
    166                Group group = null; int excess = 0;
    167                for (int idx = 0; idx < iGroups.length; idx++) {
    168                    Group g = iGroups[idx];
    169                    if (!g.canEnroll(student)) continue;
    170                    int ex = (int)Math.round(g.size() + studentWeight - g.getMaxSize());
    171                    if (group == null || ex < excess) {
    172                        group = g;
    173                        excess = ex;
    174                    }
    175                }
    176
    177                if (group != null) {
    178                    group.addStudent(student);
    179                    continue;
    180                }
    181
    182                // put the student into the first group
    183                getProgress().debug("Unable to find a valid section for student " + student.getId() + ", enrolling to " + (iGroups[0].getLecture() != null ? iGroups[0].getLecture().getName() : iGroups[0].getConfiguration().getConfigId().toString()));
    184                iGroups[0].addStudent(student);
    185            }
    186
    187            // try to move students away from groups with an excess of more than a student
    188            for (int idx = 0; idx < iGroups.length; idx++) {
    189                Group group = iGroups[idx];
    190                if (group.size() > group.getMaxSize()) {
    191                    // for each student of a group that is not enrolled in it
    192                    for (Student student : new ArrayList<Student>(group.getStudents())) {
    193                        if (group.isEnrolled(student)) continue;
    194                        // excess of a fraction of a student is allowed
    195                        if (group.size() - student.getOfferingWeight(iOfferingId) < group.getMaxSize()) continue;
    196                        // look for an available group with enough space
    197                        for (int x = 0; x < iGroups.length; x++) {
    198                            if (idx == x) continue;
    199                            if (!iGroups[x].canEnroll(student) || iGroups[x].size() >= iGroups[x].getMaxSize()) continue;
    200                            // group found, move the student away
    201                            group.removeStudent(student);
    202                            iGroups[x].addStudent(student);
    203                            break;
    204                        }
    205                        if (group.size() <= group.getMaxSize()) break;
    206                    }
    207                }
    208            }
    209
    210            return iGroups;
    211        }
    212
    213        /**
    214         * Sort students by their curriculum information and id
    215         */
    216        @Override
    217        public int compare(Student s1, Student s2) {
    218            int cmp = (s1.getCurriculum() == null ? "" : s1.getCurriculum()).compareToIgnoreCase(s2.getCurriculum() == null ? "" : s2.getCurriculum());
    219            if (cmp != 0) return cmp;
    220            cmp = (s1.getAcademicArea() == null ? "" : s1.getAcademicArea()).compareToIgnoreCase(s2.getAcademicArea() == null ? "" : s2.getAcademicArea());
    221            if (cmp != 0) return cmp;
    222            cmp = (s1.getMajor() == null ? "" : s1.getMajor()).compareToIgnoreCase(s2.getMajor() == null ? "" : s2.getMajor());
    223            if (cmp != 0) return cmp;
    224            cmp = (s1.getAcademicClassification() == null ? "" : s1.getAcademicClassification()).compareToIgnoreCase(s2.getAcademicClassification() == null ? "" : s2.getAcademicClassification());
    225            if (cmp != 0) return cmp;
    226            return s1.getId().compareTo(s2.getId());
    227        }
    228    }
    229}