    001package org.cpsolver.coursett.model;
    002
    003import java.util.Collection;
    004import java.util.List;
    005import java.util.Locale;
    006import java.util.Map;
    007
    008import org.cpsolver.coursett.model.InitialSectioning.Group;
    009import org.cpsolver.coursett.sectioning.StudentSwapSectioning;
    010import org.cpsolver.ifs.assignment.Assignment;
    011import org.cpsolver.ifs.model.InfoProvider;
    012import org.cpsolver.ifs.solution.Solution;
    013import org.cpsolver.ifs.termination.TerminationCondition;
    014import org.cpsolver.ifs.util.Progress;
    015
    016
    017/**
    018 * Default implementation of the student sectioning functions needed within the course timetabling solver
    019 * consisting of {@link InitialSectioning} and {@link FinalSectioning}.
    020 * <br>
    021 * <br>
    022 * Many course offerings consist of multiple classes, with students enrolled in
    023 * the course divided among them. These classes are often linked by a set of
    024 * constraints, namely:
    025 * <ul>
    026 * <li>Each class has a limit stating the maximum number of students who can be
    027 * enrolled in it.
    028 * <li>A student must be enrolled in exactly one class for each subpart of a
    029 * course.
    030 * <li>If two subparts of a course have a parent-child relationship, a student
    031 * enrolled in the parent class must also be enrolled in one of the child
    032 * classes.
    033 * </ul>
    034 * Moreover, some of the classes of an offering may be required or prohibited
    035 * for certain students, based on reservations that can be set on an offering, a
    036 * configuration, or a class. <br>
    037 * While the data are loaded into the solver, an initial sectioning of students into
    038 * classes is processed (see {@link InitialSectioning}). However, it
    039 * is still possible to improve on the number of student conflicts in the
    040 * solution. This can be accomplished by moving students between alternative
    041 * classes of the same course during or after the search (see
    042 * {@link FinalSectioning}).
    043 *
    044 * @version CourseTT 1.3 (University Course Timetabling)<br>
    045 *          Copyright (C) 2014 Tomáš Müller<br>
    046 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    047 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    048 * <br>
    049 *          This library is free software; you can redistribute it and/or modify
    050 *          it under the terms of the GNU Lesser General Public License as
    051 *          published by the Free Software Foundation; either version 3 of the
    052 *          License, or (at your option) any later version. <br>
    053 * <br>
    054 *          This library is distributed in the hope that it will be useful, but
    055 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    056 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    057 *          Lesser General Public License for more details. <br>
    058 * <br>
    059 *          You should have received a copy of the GNU Lesser General Public
    060 *          License along with this library; if not see
    061 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    062 */
    063public class DefaultStudentSectioning implements StudentSectioning, InfoProvider<Lecture, Placement> {
    064    protected TimetableModel iModel = null;
    065    private Progress iProgress = null;
    066    protected FinalSectioning iFinalSectioning = null;
    067    protected static java.text.DecimalFormat sDF2 = new java.text.DecimalFormat("0.00", new java.text.DecimalFormatSymbols(Locale.US));
    068
    069    /**
    070     * Constructor
    071     * @param model problem model
    072     */
    073    public DefaultStudentSectioning(TimetableModel model) {
    074        iModel = model;
    075        iFinalSectioning = new FinalSectioning(model);
    076    }
    077
    078    public Progress getProgress() {
    079        if (iProgress == null) iProgress = Progress.getInstance(iModel);
    080        return iProgress;
    081    }
    082
    083    /**
    084     * Enroll students into the given offering during the initial data load using {@link InitialSectioning}.
    085     * @param offeringId instructional offering id
    086     * @param courseName course name
    087     * @param students list of students to be sectioned
    088     * @param configurations list of configurations the students are to be sectioned into
    089     */
    090    @Override
    091    public void initialSectioning(Assignment<Lecture, Placement> assignment, Long offeringId, String courseName, Collection<Student> students, Collection<Configuration> configurations) {
    092        if (students == null || students.isEmpty())
    093            return;
    094        if (configurations == null || configurations.isEmpty())
    095            return;
    096        if (configurations.size() == 1) {
    097            Configuration cfg = configurations.iterator().next();
    098            for (Student st : students) {
    099                st.addConfiguration(cfg);
    100            }
    101            for (Long subpartId: cfg.getTopSubpartIds()) {
    102                initialSectioningLectures(assignment, offeringId, courseName, students, cfg.getTopLectures(subpartId));
    103            }
    104        } else {
    105            getProgress().trace("sectioning " + students.size() + " students of course " + courseName + " into " + configurations.size() + " configurations");
    106            Group[] studentsPerSection = studentsToConfigurations(offeringId, students, configurations);
    107            for (int i = 0; i < configurations.size(); i++) {
    108                Group group = studentsPerSection[i];
    109                getProgress().trace((i + 1) + ". configuration got " + group.getStudents().size() + " students (weighted=" + group.size() + ", cfgLimit=" + group.getConfiguration().getLimit() + ")");
    110                for (Student st : group.getStudents()) {
    111                    st.addConfiguration(group.getConfiguration());
    112                }
    113                for (Long subpartId: group.getConfiguration().getTopSubpartIds()) {
    114                    initialSectioningLectures(assignment, offeringId, courseName, group.getStudents(), group.getConfiguration().getTopLectures(subpartId));
    115                }
    116            }
    117        }
    118    }
    119
    120    /**
    121     * Class label
    122     * @param lecture a class
    123     * @return class label including a link to be printed in the log
    124     */
    125    protected String getClassLabel(Lecture lecture) {
    126        return "<A href='classDetail.do?cid=" + lecture.getClassId() + "'>" + lecture.getName() + "</A>";
    127    }
    128
    129    /**
    130     * Enroll students into the given classes during the initial data load using {@link InitialSectioning}.
    131     * @param assignment current assignment
    132     * @param offeringId instructional offering id
    133     * @param courseName course name
    134     * @param students list of students to be sectioned
    135     * @param lectures list of lectures the students are to be sectioned into
    136     */
    137    protected void initialSectioningLectures(Assignment<Lecture, Placement> assignment, Long offeringId, String courseName, Collection<Student> students, Collection<Lecture> lectures) {
    138        if (lectures == null || lectures.isEmpty())
    139            return;
    140        if (students == null || students.isEmpty())
    141            return;
    142        for (Lecture lecture : lectures) {
    143            if (lecture.classLimit(assignment) == 0 && !lecture.isCommitted())
    144                getProgress().warn("Class " + getClassLabel(lecture) + " has zero class limit.");
    145        }
    146
    147        getProgress().trace("sectioning " + students.size() + " students of course " + courseName + " into " + lectures.size() + " sections");
    148        if (lectures.size() == 1) {
    149            Lecture lect = lectures.iterator().next();
    150            for (Student st : students) {
    151                if (!st.canEnroll(lect)) {
    152                    getProgress().info("Unable to enroll student " + st.getId() + " in class " + getClassLabel(lect));
    153                }
    154                lect.addStudent(assignment, st);
    155                st.addLecture(lect);
    156            }
    157            if (lect.hasAnyChildren()) {
    158                for (Long subpartId: lect.getChildrenSubpartIds()) {
    159                    List<Lecture> children = lect.getChildren(subpartId);
    160                    initialSectioningLectures(assignment, offeringId, lect.getName(), students, children);
    161                }
    162            }
    163        } else {
    164            Group[] studentsPerSection = studentsToLectures(offeringId, students, lectures);
    165            for (int i = 0; i < studentsPerSection.length; i++) {
    166                Group group = studentsPerSection[i];
    167                Lecture lect = group.getLecture();
    168                if (group.getStudents().isEmpty()) {
    169                    getProgress().trace("Lecture " + getClassLabel(lect) + " got no students (cl=" + lect.classLimit(assignment) + ")");
    170                    continue;
    171                }
    172                getProgress().trace("Lecture " + getClassLabel(lect) + " got " + group.getStudents().size() + " students (weighted=" + group.size() + ", classLimit=" + lect.classLimit(assignment) + ")");
    173                List<Student> studentsThisSection = group.getStudents();
    174                for (Student st : studentsThisSection) {
    175                    if (!st.canEnroll(lect)) {
    176                        getProgress().info("Unable to enroll student " + st.getId() + " in class " + getClassLabel(lect));
    177                    }
    178                    lect.addStudent(assignment, st);
    179                    st.addLecture(lect);
    180                }
    181                if (lect.hasAnyChildren()) {
    182                    for (Long subpartId: lect.getChildrenSubpartIds()) {
    183                        List<Lecture> children = lect.getChildren(subpartId);
    184                        initialSectioningLectures(assignment, offeringId, lect.getName(), studentsThisSection, children);
    185                    }
    186                }
    187            }
    188        }
    189    }
    190
    191    /**
    192     * Section students into configurations. This method calls the actual initial sectioning {@link InitialSectioning#getGroups()}.
    193     * @param offeringId instructional offering id
    194     * @param students list of students to be sectioned
    195     * @param configurations list of configurations the students are to be sectioned into
    196     * @return list of {@link Group}
    197     */
    198    protected Group[] studentsToConfigurations(Long offeringId, Collection<Student> students, Collection<Configuration> configurations) {
    199        InitialSectioning sect = new InitialSectioning(getProgress(), offeringId, configurations, students);
    200        return sect.getGroups();
    201    }
    202
    203    /**
    204     * Section students into lectures. This method calls the actual initial sectioning {@link InitialSectioning#getGroups()}.
    205     * @param offeringId instructional offering id
    206     * @param students list of students to be sectioned
    207     * @param lectures list of lectures the students are to be sectioned into
    208     * @return list of {@link Group}
    209     */
    210    protected Group[] studentsToLectures(Long offeringId, Collection<Student> students, Collection<Lecture> lectures) {
    211        InitialSectioning sect = new InitialSectioning(getProgress(), offeringId, lectures, students);
    212        return sect.getGroups();
    213    }
    214
    215    /**
    216     * Return true if final student sectioning is implemented.
    217     */
    218    @Override
    219    public boolean hasFinalSectioning() {
    220        return true;
    221    }
    222
    223    /**
    224     * Run student final sectioning (switching students between sections of the same
    225     * class in order to minimize overall number of student conflicts).
    226     */
    227    @Override
    228    public void switchStudents(Solution<Lecture, Placement> solution, TerminationCondition<Lecture, Placement> termination) {
    229        iFinalSectioning.execute(solution, termination);
    230    }
    231
    232    /**
    233     * Perform sectioning on the given lecture
    234     * @param lecture given lecture
    235     * @param recursive recursively resection lectures affected by a student swap
    236     * @param configAsWell resection students between configurations as well
    237     **/
    238    @Override
    239    public void resection(Assignment<Lecture, Placement> assignment, Lecture lecture, boolean recursive, boolean configAsWell) {
    240        iFinalSectioning.resection(assignment, lecture, recursive, configAsWell);
    241    }
    242
    243    @Override
    244    public void getInfo(Assignment<Lecture, Placement> assignment, Map<String, String> info) {
    245        if (!iModel.getStudentGroups().isEmpty())
    246            info.put("Student groups", sDF2.format(100.0 * StudentSwapSectioning.group(iModel) / iModel.getStudentGroups().size()) + "%");
    247    }
    248
    249    @Override
    250    public void getInfo(Assignment<Lecture, Placement> assignment, Map<String, String> info, Collection<Lecture> variables) {
    251        if (!iModel.getStudentGroups().isEmpty())
    252            info.put("Student groups", sDF2.format(StudentSwapSectioning.gp(iModel, variables)) + "%");
    253    }
    254}