    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 * @author  Tomáš Müller
    036 * @version CourseTT 1.3 (University Course Timetabling)<br>
    037 *          Copyright (C) 2014 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 *          This customization has been implemented for <a href='http://www.agh.pl'>AGH, Poland</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 DeterministicStudentSectioning extends DefaultStudentSectioning {
    057    public DeterministicStudentSectioning(TimetableModel model) {
    058        super(model);
    059    }
    060
    061    @Override
    062    protected Group[] studentsToConfigurations(Long offeringId, Collection<Student> students, Collection<Configuration> configurations) {
    063        DeterministicInitialSectioning sect = new DeterministicInitialSectioning(getProgress(), offeringId, configurations, students);
    064        return sect.getGroups();
    065    }
    066
    067    @Override
    068    protected Group[] studentsToLectures(Long offeringId, Collection<Student> students, Collection<Lecture> lectures) {
    069        Set<Lecture> sortedLectures = new TreeSet<Lecture>(new Comparator<Lecture>() {
    070            @Override
    071            public int compare(Lecture l1, Lecture l2) {
    072                return l1.getClassId().compareTo(l2.getClassId());
    073            }
    074        });
    075        sortedLectures.addAll(lectures);
    076        DeterministicInitialSectioning sect = new DeterministicInitialSectioning(getProgress(), offeringId, sortedLectures, students);
    077        return sect.getGroups();
    078    }
    079
    080    /**
    081     * No re-sectioning (final sectioning) during deterministic student sectioning.
    082     */
    083    @Override
    084    public boolean hasFinalSectioning() {
    085        return false;
    086    }
    087
    088    /**
    089     * No re-sectioning (final sectioning) during deterministic student sectioning.
    090     */
    091    @Override
    092    public void switchStudents(Solution<Lecture, Placement> solution, TerminationCondition<Lecture, Placement> termination) {
    093    }
    094
    095    /**
    096     * No re-sectioning (final sectioning) during deterministic student sectioning.
    097     */
    098    @Override
    099    public void resection(Assignment<Lecture, Placement> assignment, Lecture lecture, boolean recursive, boolean configAsWell) {
    100    }
    101
    102    /**
    103     * Assign students to groups in a deterministic way, i.e., first student to first available group etc.
    104     * @author Tomáš Müller
    105     */
    106    public static class DeterministicInitialSectioning extends InitialSectioning implements Comparator<Student> {
    107
    108        public DeterministicInitialSectioning(Progress progress, Long offeringId, Collection<?> lectureOrConfigurations, Collection<Student> students) {
    109            super(progress, offeringId, lectureOrConfigurations, students);
    110
    111            // Sort students by their curriculum information first
    112            iStudents = new TreeSet<Student>(this); iStudents.addAll(students);
    113        }
    114
    115        @Override
    116        protected void tweakSizes(double total) {
    117            double studentsWeight = 0;
    118            for (Student s : iStudents) {
    119                studentsWeight += s.getOfferingWeight(iOfferingId);
    120            }
    121
    122            // if there is not enough space for the given students
    123            if (studentsWeight > total) {
    124                if (total == 0) {
    125                    // all limits are zero -> spread students equally
    126                    for (int idx = 0; idx < iGroups.length; idx++)
    127                        iGroups[idx].setMaxSize(total / iGroups.length);
    128                } else {
    129                    // enlarge sections proportionally
    130                    double factor = studentsWeight / total;
    131                    for (int idx = 0; idx < iGroups.length; idx++) {
    132                        iGroups[idx].setMaxSize(factor * iGroups[idx].getMaxSize());
    133                        iGroups[idx].setMinSize(Math.min(iGroups[idx].getMinSize(), 0.9 * iGroups[idx].getMaxSize()));
    134                   }
    135                }
    136            }
    137        }
    138
    139        @Override
    140        public Group[] getGroups() {
    141            // Assign already enrolled students first
    142            students: for (Iterator<Student> i = iStudents.iterator(); i.hasNext();) {
    143                Student student = i.next();
    144                for (int idx = 0; idx < iGroups.length; idx++) {
    145                    if (iGroups[idx].isEnrolled(student)) {
    146                        iGroups[idx].addStudent(student);
    147                        i.remove();
    148                        continue students;
    149                    }
    150                }
    151            }
    152
    153            // For all other (not enrolled) students
    154            students: for (Student student : iStudents) {
    155                double studentWeight = student.getOfferingWeight(iOfferingId);
    156
    157                // enroll into first available group with enough space
    158                for (int idx = 0; idx < iGroups.length; idx++) {
    159                    Group g = iGroups[idx];
    160                    if (!g.canEnroll(student) || g.size() >= g.getMaxSize()) continue;
    161                    // group found -> enroll and continue with the next student
    162                    g.addStudent(student);
    163                    continue students;
    164                }
    165
    166                // disobey max size, but prefer sections with smallest excess
    167                Group group = null; int excess = 0;
    168                for (int idx = 0; idx < iGroups.length; idx++) {
    169                    Group g = iGroups[idx];
    170                    if (!g.canEnroll(student)) continue;
    171                    int ex = (int)Math.round(g.size() + studentWeight - g.getMaxSize());
    172                    if (group == null || ex < excess) {
    173                        group = g;
    174                        excess = ex;
    175                    }
    176                }
    177
    178                if (group != null) {
    179                    group.addStudent(student);
    180                    continue;
    181                }
    182
    183                // put the student into the first group
    184                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()));
    185                iGroups[0].addStudent(student);
    186            }
    187
    188            // try to move students away from groups with an excess of more than a student
    189            for (int idx = 0; idx < iGroups.length; idx++) {
    190                Group group = iGroups[idx];
    191                if (group.size() > group.getMaxSize()) {
    192                    // for each student of a group that is not enrolled in it
    193                    for (Student student : new ArrayList<Student>(group.getStudents())) {
    194                        if (group.isEnrolled(student)) continue;
    195                        // excess of a fraction of a student is allowed
    196                        if (group.size() - student.getOfferingWeight(iOfferingId) < group.getMaxSize()) continue;
    197                        // look for an available group with enough space
    198                        for (int x = 0; x < iGroups.length; x++) {
    199                            if (idx == x) continue;
    200                            if (!iGroups[x].canEnroll(student) || iGroups[x].size() >= iGroups[x].getMaxSize()) continue;
    201                            // group found, move the student away
    202                            group.removeStudent(student);
    203                            iGroups[x].addStudent(student);
    204                            break;
    205                        }
    206                        if (group.size() <= group.getMaxSize()) break;
    207                    }
    208                }
    209            }
    210
    211            return iGroups;
    212        }
    213
    214        /**
    215         * Sort students by their curriculum information and id
    216         */
    217        @Override
    218        public int compare(Student s1, Student s2) {
    219            int cmp = (s1.getCurriculum() == null ? "" : s1.getCurriculum()).compareToIgnoreCase(s2.getCurriculum() == null ? "" : s2.getCurriculum());
    220            if (cmp != 0) return cmp;
    221            cmp = (s1.getAcademicArea() == null ? "" : s1.getAcademicArea()).compareToIgnoreCase(s2.getAcademicArea() == null ? "" : s2.getAcademicArea());
    222            if (cmp != 0) return cmp;
    223            cmp = (s1.getMajor() == null ? "" : s1.getMajor()).compareToIgnoreCase(s2.getMajor() == null ? "" : s2.getMajor());
    224            if (cmp != 0) return cmp;
    225            cmp = (s1.getAcademicClassification() == null ? "" : s1.getAcademicClassification()).compareToIgnoreCase(s2.getAcademicClassification() == null ? "" : s2.getAcademicClassification());
    226            if (cmp != 0) return cmp;
    227            return s1.getId().compareTo(s2.getId());
    228        }
    229    }
    230}