001package org.cpsolver.coursett.criteria.additional;
002
003import java.util.Collection;
004import java.util.HashSet;
005import java.util.Map;
006import java.util.Set;
007
008import org.cpsolver.coursett.constraint.JenrlConstraint;
009import org.cpsolver.coursett.criteria.StudentConflict;
010import org.cpsolver.coursett.model.Lecture;
011import org.cpsolver.coursett.model.Placement;
012import org.cpsolver.coursett.model.Student;
013import org.cpsolver.coursett.model.TimeLocation;
014import org.cpsolver.coursett.model.TimetableModel;
015import org.cpsolver.ifs.assignment.Assignment;
016import org.cpsolver.ifs.util.DataProperties;
017
018/**
019 * Naive, yet effective approach for minimizing number of days in student schedule. This criterion
020 * is based on {@link StudentConflict} and it penalizes all cases where a student has
021 * two classes taught on different days.
022 * These penalties are weighted by Comparator.MinimizeStudentScheduleDaysWeight,
023 * which defaults to 1/20 of the Comparator.StudentConflictWeight.
024 * 
025 * <br>
026 * 
027 * @author  Tomáš Müller
028 * @version CourseTT 1.3 (University Course Timetabling)<br>
029 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
032 * <br>
033 *          This library is free software; you can redistribute it and/or modify
034 *          it under the terms of the GNU Lesser General Public License as
035 *          published by the Free Software Foundation; either version 3 of the
036 *          License, or (at your option) any later version. <br>
037 * <br>
038 *          This library is distributed in the hope that it will be useful, but
039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
041 *          Lesser General Public License for more details. <br>
042 * <br>
043 *          You should have received a copy of the GNU Lesser General Public
044 *          License along with this library; if not see
045 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
046 */
047public class StudentMinimizeDaysOfWeek extends StudentConflict {
048    
049    /**
050     * Time distance between two placements in the number of days. The classes must be on the weeks.
051     * If the two classes are taught on multiple days during the week, the
052     * distance only count the different days.
053     * @param p1 first placement
054     * @param p2 second placement
055     * @return number of different days
056     */
057    public static double dayDistance(Placement p1, Placement p2) {
058        if (p1 == null || p2 == null) return 0;
059        return dayDistance(p1.getTimeLocation(), p2.getTimeLocation());
060    }
061    
062    private static double dayDistance(TimeLocation t1, TimeLocation t2) {
063        if (!t1.shareWeeks(t2)) return 0.0;
064        return 1.0 - ((double)t1.nrSharedDays(t2)) / Math.min(t1.getNrMeetings(), t2.getNrMeetings());
065    }
066    
067    @Override
068    public boolean inConflict(Placement p1, Placement p2) {
069        return dayDistance(p1, p2) > 0.0;
070    }
071    
072    @Override
073    protected double jointEnrollment(JenrlConstraint jenrl, Placement p1, Placement p2) {
074        return dayDistance(p1, p2) * jenrl.jenrl();
075    }
076    
077    @Override
078    protected double jointEnrollment(JenrlConstraint jenrl) {
079        double max = 0;
080        for (TimeLocation t1: jenrl.first().timeLocations())
081            for (TimeLocation t2: jenrl.second().timeLocations()) {
082                double distance = dayDistance(t1, t2);
083                if (distance > max) max = distance;
084            }
085        return max;
086    }
087    
088    @Override
089    public boolean isApplicable(Lecture l1, Lecture l2) {
090        return l1 != null && l2 != null && !ignore(l1, l2) && applicable(l1, l2);
091    }
092    
093    @Override
094    public void incJenrl(Assignment<Lecture, Placement> assignment, JenrlConstraint jenrl, double studentWeight, Double conflictPriority, Student student) {
095        if (isApplicable(student, jenrl.first(), jenrl.second()))
096            inc(assignment, studentWeight * dayDistance(assignment.getValue(jenrl.first()), assignment.getValue(jenrl.second())));
097    }
098    
099    @Override
100    public double getWeightDefault(DataProperties config) {
101        return config.getPropertyDouble("Comparator.MinimizeStudentScheduleDaysWeight", 0.05 * config.getPropertyDouble("Comparator.StudentConflictWeight", 1.0));
102    }
103    
104    @Override
105    public String getPlacementSelectionWeightName() {
106        return "Placement.MinimizeStudentScheduleDaysWeight";
107    }
108
109    @Override
110    public void getInfo(Assignment<Lecture, Placement> assignment, Map<String, String> info) {
111        super.getInfo(assignment, info);
112        double total = 0;
113        for (JenrlConstraint jenrl: ((TimetableModel)getModel()).getJenrlConstraints()) {
114            if (!jenrl.isToBeIgnored())
115                total += jenrl.jenrl();
116        }
117        info.put("Student different days", sDoubleFormat.format(getValue(assignment) / total));
118    }
119    
120    @Override
121    public void getInfo(Assignment<Lecture, Placement> assignment, Map<String, String> info, Collection<Lecture> variables) {
122        super.getInfo(assignment, info, variables);
123        Set<JenrlConstraint> jenrls = new HashSet<JenrlConstraint>();
124        double distance = 0;
125        double total = 0;
126        for (Lecture lecture: variables) {
127            for (JenrlConstraint jenrl: lecture.jenrlConstraints())
128                if (jenrls.add(jenrl) && !jenrl.isToBeIgnored()) {
129                    distance += jenrl.jenrl() * dayDistance(assignment.getValue(jenrl.first()), assignment.getValue(jenrl.second()));
130                    total += jenrl.jenrl();
131                }
132        }
133        info.put("Student different days", sDoubleFormat.format(distance / total));
134    }
135
136}