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