001package org.cpsolver.coursett.criteria;
002
003import java.util.List;
004
005import org.cpsolver.coursett.Constants;
006import org.cpsolver.coursett.constraint.RoomConstraint.RoomConstraintContext;
007import org.cpsolver.coursett.model.Placement;
008import org.cpsolver.coursett.model.TimeLocation;
009import org.cpsolver.ifs.util.DataProperties;
010
011
012/**
013 * Useless half-hours. This criterion counts cases when there is an empty half hour in a room.
014 * Such half-hours should be generally avoided as usually any class takes more than half an hour.  
015 * <br>
016 * 
017 * @author  Tomáš Müller
018 * @version CourseTT 1.3 (University Course Timetabling)<br>
019 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
022 * <br>
023 *          This library is free software; you can redistribute it and/or modify
024 *          it under the terms of the GNU Lesser General Public License as
025 *          published by the Free Software Foundation; either version 3 of the
026 *          License, or (at your option) any later version. <br>
027 * <br>
028 *          This library is distributed in the hope that it will be useful, but
029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
031 *          Lesser General Public License for more details. <br>
032 * <br>
033 *          You should have received a copy of the GNU Lesser General Public
034 *          License along with this library; if not see
035 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
036 */
037public class UselessHalfHours extends BrokenTimePatterns {
038
039    @Override
040    public double getWeightDefault(DataProperties config) {
041        return Constants.sPreferenceLevelStronglyDiscouraged * config.getPropertyDouble("Comparator.UselessSlotWeight", 0.1);
042    }
043    
044    @Override
045    public String getPlacementSelectionWeightName() {
046        return "Placement.UselessSlotsWeight";
047    }
048    
049    @Override
050    protected double penalty(RoomConstraintContext rc) {
051        return countUselessSlotsHalfHours(rc);
052    }
053
054    @Override
055    protected double penalty(RoomConstraintContext rc, Placement value) {
056        return countUselessSlotsHalfHours(rc, value);
057    }
058    
059    private static boolean isEmpty(RoomConstraintContext rc, int slot, Placement placement) {
060        List<Placement> assigned = rc.getPlacements(slot);
061        return assigned.isEmpty() || (placement != null && assigned.size() == 1 && assigned.get(0).variable().equals(placement.variable()));
062    }
063
064    
065    private static boolean isUselessBefore(RoomConstraintContext rc, int slot, Placement placement) {
066        int s = slot % Constants.SLOTS_PER_DAY;
067        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
068            return false;
069        return (!isEmpty(rc, slot - 1, placement) &&
070                isEmpty(rc, slot + 0, placement) &&
071                isEmpty(rc, slot + 1, placement) &&
072                isEmpty(rc, slot + 2, placement) &&
073                isEmpty(rc, slot + 3, placement) &&
074                isEmpty(rc, slot + 4, placement) &&
075                isEmpty(rc, slot + 5, placement) &&
076                isEmpty(rc, slot + 6, placement));
077    }
078
079    private static boolean isUselessAfter(RoomConstraintContext rc, int slot, Placement placement) {
080        int s = slot % Constants.SLOTS_PER_DAY;
081        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
082            return false;
083        return (isEmpty(rc, slot - 1, placement) &&
084                isEmpty(rc, slot + 0, placement) &&
085                isEmpty(rc, slot + 1, placement) &&
086                isEmpty(rc, slot + 2, placement) &&
087                isEmpty(rc, slot + 3, placement) &&
088                isEmpty(rc, slot + 4, placement) &&
089                isEmpty(rc, slot + 5, placement) &&
090                !isEmpty(rc, slot + 6, placement));
091    }
092    
093    private static boolean isUseless(RoomConstraintContext rc, int slot, Placement placement) {
094        int s = slot % Constants.SLOTS_PER_DAY;
095        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
096            return false;
097        return (!isEmpty(rc, slot - 1, placement) &&
098                isEmpty(rc, slot + 0, placement) &&
099                isEmpty(rc, slot + 1, placement) &&
100                isEmpty(rc, slot + 2, placement) &&
101                isEmpty(rc, slot + 3, placement) &&
102                isEmpty(rc, slot + 4, placement) &&
103                isEmpty(rc, slot + 5, placement) &&
104                !isEmpty(rc, slot + 6, placement));
105    }
106
107    /** Number of useless half hours for this room 
108     * @param rc room constraint assignment context
109     * @param placement placement that is being considered
110     * @return number of useless slots caused by the given placement
111     **/
112    protected static int countUselessSlotsHalfHours(RoomConstraintContext rc, Placement placement) {
113        int ret = 0;
114        TimeLocation time = placement.getTimeLocation();
115        int slot = time.getStartSlot() % Constants.SLOTS_PER_DAY;
116        int days = time.getDayCode();
117        for (int d = 0; d < Constants.NR_DAYS; d++) {
118            if ((Constants.DAY_CODES[d] & days) == 0)
119                continue;
120            if (isUselessBefore(rc, d * Constants.SLOTS_PER_DAY + slot - 6, placement))
121                ret ++;
122            if (isUselessAfter(rc, d * Constants.SLOTS_PER_DAY + slot + time.getNrSlotsPerMeeting(), placement))
123                ret ++;
124            if (time.getNrSlotsPerMeeting() == 6 && isUseless(rc, d * Constants.SLOTS_PER_DAY + slot, placement))
125                ret --;
126        }
127        return ret;
128    }
129    
130    private static boolean isUseless(RoomConstraintContext rc, int slot) {
131        int s = slot % Constants.SLOTS_PER_DAY;
132        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
133            return false;
134        return (!rc.getPlacements(slot - 1).isEmpty() &&
135                rc.getPlacements(slot + 0).isEmpty() &&
136                rc.getPlacements(slot + 1).isEmpty() &&
137                rc.getPlacements(slot + 2).isEmpty() &&
138                rc.getPlacements(slot + 3).isEmpty() &&
139                rc.getPlacements(slot + 4).isEmpty() &&
140                rc.getPlacements(slot + 5).isEmpty() &&
141                !rc.getPlacements(slot + 6).isEmpty());
142    }
143
144    /** Number of useless slots for this room 
145     * @param rc room constraint assignment context
146     * @return current penalty for the given room
147     **/
148    public static int countUselessSlotsHalfHours(RoomConstraintContext rc) {
149        int ret = 0;
150        for (int d = 0; d < Constants.NR_DAYS; d++) {
151            for (int s = 0; s < Constants.SLOTS_PER_DAY; s++) {
152                int slot = d * Constants.SLOTS_PER_DAY + s;
153                if (isUseless(rc, slot))
154                    ret++;
155            }
156        }
157        return ret;
158    }
159}