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}