001package net.sf.cpsolver.coursett.model;
002
003import java.util.Collection;
004import java.util.List;
005
006import net.sf.cpsolver.coursett.model.InitialSectioning.Group;
007import net.sf.cpsolver.ifs.util.Progress;
008
009/**
010 * Default implementation of the student sectioning functions needed within the course timetabling solver
011 * consisting of {@link InitialSectioning} and {@link FinalSectioning}.
012 * <br>
013 * <br>
014 * Many course offerings consist of multiple classes, with students enrolled in
015 * the course divided among them. These classes are often linked by a set of
016 * constraints, namely:
017 * <ul>
018 * <li>Each class has a limit stating the maximum number of students who can be
019 * enrolled in it.
020 * <li>A student must be enrolled in exactly one class for each subpart of a
021 * course.
022 * <li>If two subparts of a course have a parent-child relationship, a student
023 * enrolled in the parent class must also be enrolled in one of the child
024 * classes.
025 * </ul>
026 * Moreover, some of the classes of an offering may be required or prohibited
027 * for certain students, based on reservations that can be set on an offering, a
028 * configuration, or a class. <br>
029 * While the data are loaded into the solver, an initial sectioning of students into
030 * classes is processed (see {@link InitialSectioning}). However, it
031 * is still possible to improve on the number of student conflicts in the
032 * solution. This can be accomplished by moving students between alternative
033 * classes of the same course during or after the search (see
034 * {@link FinalSectioning}).
035 * 
036 * @version CourseTT 1.2 (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 * <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 DefaultStudentSectioning implements StudentSectioning {
056    protected TimetableModel iModel = null;
057    private Progress iProgress = null;
058    protected FinalSectioning iFinalSectioning = null;
059    
060    /**
061     * Constructor
062     */
063    public DefaultStudentSectioning(TimetableModel model) {
064        iModel = model;
065        iFinalSectioning = new FinalSectioning(model);
066    }
067    
068    public Progress getProgress() {
069        if (iProgress == null) iProgress = Progress.getInstance(iModel);
070        return iProgress;
071    }
072
073    /**
074     * Enroll students into the given offering during the initial data load using {@link InitialSectioning}.
075     * @param offeringId instructional offering id
076     * @param courseName course name
077     * @param students list of students to be sectioned
078     * @param configurations list of configurations the students are to be sectioned into
079     */
080    @Override
081    public void initialSectioning(Long offeringId, String courseName, Collection<Student> students, Collection<Configuration> configurations) {
082        if (students == null || students.isEmpty())
083            return;
084        if (configurations == null || configurations.isEmpty())
085            return;
086        if (configurations.size() == 1) {
087            Configuration cfg = configurations.iterator().next();
088            for (Student st : students) {
089                st.addConfiguration(cfg);
090            }
091            for (Long subpartId: cfg.getTopSubpartIds()) {
092                initialSectioningLectures(offeringId, courseName, students, cfg.getTopLectures(subpartId));
093            }
094        } else {
095            getProgress().trace("sectioning " + students.size() + " students of course " + courseName + " into " + configurations.size() + " configurations");
096            Group[] studentsPerSection = studentsToConfigurations(offeringId, students, configurations);
097            for (int i = 0; i < configurations.size(); i++) {
098                Group group = studentsPerSection[i];
099                getProgress().trace((i + 1) + ". configuration got " + group.getStudents().size() + " students (weighted=" + group.size() + ", cfgLimit=" + group.getConfiguration().getLimit() + ")");
100                for (Student st : group.getStudents()) {
101                    st.addConfiguration(group.getConfiguration());
102                }
103                for (Long subpartId: group.getConfiguration().getTopSubpartIds()) {
104                    initialSectioningLectures(offeringId, courseName, group.getStudents(), group.getConfiguration().getTopLectures(subpartId));
105                }
106            }
107        }
108    }
109    
110    /**
111     * Class label
112     * @param lecture a class
113     * @return class label including a link to be printed in the log
114     */
115    protected String getClassLabel(Lecture lecture) {
116        return "<A href='classDetail.do?cid=" + lecture.getClassId() + "'>" + lecture.getName() + "</A>";
117    }
118    
119    /**
120     * Enroll students into the given classes during the initial data load using {@link InitialSectioning}.
121     * @param offeringId instructional offering id
122     * @param courseName course name
123     * @param students list of students to be sectioned
124     * @param lectures list of lectures the students are to be sectioned into
125     */
126    protected void initialSectioningLectures(Long offeringId, String courseName, Collection<Student> students, Collection<Lecture> lectures) {
127        if (lectures == null || lectures.isEmpty())
128            return;
129        if (students == null || students.isEmpty())
130            return;
131        for (Lecture lecture : lectures) {
132            if (lecture.classLimit() == 0 && !lecture.isCommitted())
133                getProgress().warn("Class " + getClassLabel(lecture) + " has zero class limit.");
134        }
135
136        getProgress().trace("sectioning " + students.size() + " students of course " + courseName + " into " + lectures.size() + " sections");
137        if (lectures.size() == 1) {
138            Lecture lect = lectures.iterator().next();
139            for (Student st : students) {
140                if (!st.canEnroll(lect)) {
141                    getProgress().info("Unable to enroll student " + st.getId() + " in class " + getClassLabel(lect));
142                }
143                lect.addStudent(st);
144                st.addLecture(lect);
145            }
146            if (lect.hasAnyChildren()) {
147                for (Long subpartId: lect.getChildrenSubpartIds()) {
148                    List<Lecture> children = lect.getChildren(subpartId);
149                    initialSectioningLectures(offeringId, lect.getName(), students, children);
150                }
151            }
152        } else {
153            Group[] studentsPerSection = studentsToLectures(offeringId, students, lectures);
154            for (int i = 0; i < studentsPerSection.length; i++) {
155                Group group = studentsPerSection[i];
156                Lecture lect = group.getLecture();
157                if (group.getStudents().isEmpty()) {
158                    getProgress().trace("Lecture " + getClassLabel(lect) + " got no students (cl=" + lect.classLimit() + ")");
159                    continue;
160                }
161                getProgress().trace("Lecture " + getClassLabel(lect) + " got " + group.getStudents().size() + " students (weighted=" + group.size() + ", classLimit=" + lect.classLimit() + ")");
162                List<Student> studentsThisSection = group.getStudents();
163                for (Student st : studentsThisSection) {
164                    if (!st.canEnroll(lect)) {
165                        getProgress().info("Unable to enroll student " + st.getId() + " in class " + getClassLabel(lect));
166                    }
167                    lect.addStudent(st);
168                    st.addLecture(lect);
169                }
170                if (lect.hasAnyChildren()) {
171                    for (Long subpartId: lect.getChildrenSubpartIds()) {
172                        List<Lecture> children = lect.getChildren(subpartId);
173                        initialSectioningLectures(offeringId, lect.getName(), studentsThisSection, children);
174                    }
175                }
176            }
177        }
178    }
179    
180    /**
181     * Section students into configurations. This method calls the actual initial sectioning {@link InitialSectioning#getGroups()}.
182     * @param offeringId instructional offering id
183     * @param students list of students to be sectioned
184     * @param configurations list of configurations the students are to be sectioned into
185     * @return list of {@link Group}
186     */
187    protected Group[] studentsToConfigurations(Long offeringId, Collection<Student> students, Collection<Configuration> configurations) {
188        InitialSectioning sect = new InitialSectioning(getProgress(), offeringId, configurations, students);
189        return sect.getGroups();
190    }
191    
192    /**
193     * Section students into lectures. This method calls the actual initial sectioning {@link InitialSectioning#getGroups()}.
194     * @param offeringId instructional offering id
195     * @param students list of students to be sectioned
196     * @param lectures list of lectures the students are to be sectioned into
197     * @return list of {@link Group}
198     */
199    protected Group[] studentsToLectures(Long offeringId, Collection<Student> students, Collection<Lecture> lectures) {
200        InitialSectioning sect = new InitialSectioning(getProgress(), offeringId, lectures, students);
201        return sect.getGroups();
202    }
203    
204    /**
205     * Return true if final student sectioning is implemented.
206     */
207    @Override
208    public boolean hasFinalSectioning() {
209        return true;
210    }
211
212    /**
213     * Run student final sectioning (switching students between sections of the same
214     * class in order to minimize overall number of student conflicts).
215     */
216    @Override
217    public void switchStudents(TimetableModel model) {
218        iFinalSectioning.run();
219    }
220    
221    /**
222     * Perform sectioning on the given lecture
223     * @param lecture given lecture
224     * @param recursive recursively resection lectures affected by a student swap
225     * @param configAsWell resection students between configurations as well
226     **/
227    @Override
228    public void resection(Lecture lecture, boolean recursive, boolean configAsWell) {
229        iFinalSectioning.resection(lecture, recursive, configAsWell);
230    }
231
232}