001package net.sf.cpsolver.coursett.criteria; 002 003import java.util.Collection; 004import java.util.HashSet; 005import java.util.Set; 006 007import net.sf.cpsolver.coursett.Constants; 008import net.sf.cpsolver.coursett.constraint.InstructorConstraint; 009import net.sf.cpsolver.coursett.model.Lecture; 010import net.sf.cpsolver.coursett.model.Placement; 011import net.sf.cpsolver.coursett.model.TimetableModel; 012 013import net.sf.cpsolver.ifs.util.DataProperties; 014 015/** 016 * Bact-to-back instructor preferences. This criterion counts cases when an instructor 017 * has to teach two classes in two rooms that are too far a part. This objective 018 * is counter by the {@link InstructorConstraint} 019 * (see {@link InstructorConstraint#getDistancePreference(Placement, Placement)}). 020 * <br> 021 * 022 * @version CourseTT 1.2 (University Course Timetabling)<br> 023 * Copyright (C) 2006 - 2011 Tomáš Müller<br> 024 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 025 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 026 * <br> 027 * This library is free software; you can redistribute it and/or modify 028 * it under the terms of the GNU Lesser General Public License as 029 * published by the Free Software Foundation; either version 3 of the 030 * License, or (at your option) any later version. <br> 031 * <br> 032 * This library is distributed in the hope that it will be useful, but 033 * WITHOUT ANY WARRANTY; without even the implied warranty of 034 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 035 * Lesser General Public License for more details. <br> 036 * <br> 037 * You should have received a copy of the GNU Lesser General Public 038 * License along with this library; if not see 039 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 040 */ 041public class BackToBackInstructorPreferences extends TimetablingCriterion { 042 043 public BackToBackInstructorPreferences() { 044 iValueUpdateType = ValueUpdateType.NoUpdate; 045 } 046 047 @Override 048 public double getWeightDefault(DataProperties config) { 049 return Constants.sPreferenceLevelDiscouraged * config.getPropertyDouble("Comparator.DistanceInstructorPreferenceWeight", 1.0); 050 } 051 052 @Override 053 public String getPlacementSelectionWeightName() { 054 return "Placement.DistanceInstructorPreferenceWeight"; 055 } 056 057 protected int penalty(Placement value) { 058 int ret = 0; 059 for (InstructorConstraint ic: value.variable().getInstructorConstraints()) { 060 ret += ic.getPreference(value); 061 } 062 return ret; 063 } 064 065 @Override 066 public double getValue(Placement value, Set<Placement> conflicts) { 067 double ret = penalty(value); 068 if (conflicts != null) 069 for (Placement conflict: conflicts) 070 ret -= penalty(conflict); 071 return ret; 072 } 073 074 @Override 075 public double getValue(Collection<Lecture> variables) { 076 double ret = 0; 077 Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>(); 078 for (Lecture lect: variables) { 079 for (InstructorConstraint ic: lect.getInstructorConstraints()) { 080 if (!constraints.add(ic)) continue; 081 ret += ic.getPreference(); 082 } 083 } 084 return ret; 085 } 086 087 @Override 088 protected double[] computeBounds() { 089 double[] bounds = new double[] { 0.0, 0.0 }; 090 for (InstructorConstraint ic: ((TimetableModel)getModel()).getInstructorConstraints()) 091 bounds[1] += ic.getWorstPreference(); 092 return bounds; 093 } 094 095 @Override 096 public double[] getBounds(Collection<Lecture> variables) { 097 double[] bounds = new double[] { 0.0, 0.0 }; 098 Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>(); 099 for (Lecture lect: variables) { 100 for (InstructorConstraint ic: lect.getInstructorConstraints()) { 101 if (!constraints.add(ic)) continue; 102 bounds[1] += ic.getWorstPreference(); 103 } 104 } 105 return bounds; 106 } 107}