net.sf.cpsolver.exam.heuristics

Class ExamHillClimbing

java.lang.Object

net.sf.cpsolver.exam.heuristics.ExamHillClimbing

All Implemented Interfaces:

NeighbourSelection<Exam,ExamPlacement>, LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>, SolutionListener<Exam,ExamPlacement>

public class ExamHillClimbing
extends Object
implements NeighbourSelection<Exam,ExamPlacement>, SolutionListener<Exam,ExamPlacement>, LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>

Hill climber. In each iteration, one of the following three neighbourhoods is selected first

• random move (ExamRandomMove)
• period swap (ExamTimeMove)
• room swap (ExamRoomMove)

, then a neighbour is generated and it is accepted if its value ExamSimpleNeighbour.value() is below or equal to zero. The search is stopped after a given amount of idle iterations ( can be defined by problem property HillClimber.MaxIdle).

Version:

ExamTT 1.2 (Examination Timetabling)
Copyright (C) 2008 - 2010 Tomáš Müller
muller@unitime.org
http://muller.unitime.org

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not see http://www.gnu.org/licenses/.

Constructor Summary

Constructors

Constructor and Description
ExamHillClimbing(DataProperties properties) Constructor
ExamHillClimbing(DataProperties properties, String name) Constructor

Method Summary

Modifier and Type	Method and Description
boolean	accept(LazyNeighbour<Exam,ExamPlacement> neighbour, double value) Accept lazy neighbour
void	bestCleared(Solution<Exam,ExamPlacement> solution) Called by the solution when method Solution.clearBest() is called.
void	bestRestored(Solution<Exam,ExamPlacement> solution) Called by the solution when method Solution.restoreBest() is called.
void	bestSaved(Solution<Exam,ExamPlacement> solution) Memorize the iteration when the last best solution was found.
void	getInfo(Solution<Exam,ExamPlacement> solution, Map<String,String> info) Called by the solution when it is asked to produce info table, see Solution.getInfo().
void	getInfo(Solution<Exam,ExamPlacement> solution, Map<String,String> info, Collection<Exam> variables) Called by the solution when it is asked to produce info table, see Solution.getInfo().
void	init(Solver<Exam,ExamPlacement> solver) Initialization
Neighbour<Exam,ExamPlacement>	selectNeighbour(Solution<Exam,ExamPlacement> solution) Select one of the given neighbourhoods randomly, select neighbour, return it if its value is below or equal to zero (continue with the next selection otherwise).
void	solutionUpdated(Solution<Exam,ExamPlacement> solution) Called by the solution when it is updated, see Solution.update(double).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExamHillClimbing

public ExamHillClimbing(DataProperties properties)

Constructor

Parameters:

properties - problem properties (use HillClimber.MaxIdle to set maximum number of idle iterations)

ExamHillClimbing

public ExamHillClimbing(DataProperties properties,
                        String name)

Constructor

Parameters:

properties - problem properties (use HillClimber.MaxIdle to set maximum number of idle iterations)

Method Detail

init

public void init(Solver<Exam,ExamPlacement> solver)

Initialization

Specified by:

init in interface NeighbourSelection<Exam,ExamPlacement>

selectNeighbour

public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)

Select one of the given neighbourhoods randomly, select neighbour, return it if its value is below or equal to zero (continue with the next selection otherwise). Return null when the given number of idle iterations is reached.

Specified by:

selectNeighbour in interface NeighbourSelection<Exam,ExamPlacement>

Parameters:

solution - given solution

Returns:

a neighbour assignment

bestSaved

public void bestSaved(Solution<Exam,ExamPlacement> solution)

Memorize the iteration when the last best solution was found.

Specified by:

bestSaved in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

solutionUpdated

public void solutionUpdated(Solution<Exam,ExamPlacement> solution)

Description copied from interface: SolutionListener

Called by the solution when it is updated, see Solution.update(double).

Specified by:

solutionUpdated in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

getInfo

public void getInfo(Solution<Exam,ExamPlacement> solution,
                    Map<String,String> info)

Description copied from interface: SolutionListener

Called by the solution when it is asked to produce info table, see Solution.getInfo(). A listener can also add some its info into this table.

Specified by:

getInfo in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

info - produced info table

getInfo

public void getInfo(Solution<Exam,ExamPlacement> solution,
                    Map<String,String> info,
                    Collection<Exam> variables)

Description copied from interface: SolutionListener

Called by the solution when it is asked to produce info table, see Solution.getInfo(). A listener can also add some its info into this table.

Specified by:

getInfo in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

info - produced info table

variables - only variables from this set are included

bestCleared

public void bestCleared(Solution<Exam,ExamPlacement> solution)

Description copied from interface: SolutionListener

Called by the solution when method Solution.clearBest() is called.

Specified by:

bestCleared in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

bestRestored

public void bestRestored(Solution<Exam,ExamPlacement> solution)

Description copied from interface: SolutionListener

Called by the solution when method Solution.restoreBest() is called.

Specified by:

bestRestored in interface SolutionListener<Exam,ExamPlacement>

Parameters:

solution - source solution

accept

public boolean accept(LazyNeighbour<Exam,ExamPlacement> neighbour,
                      double value)

Accept lazy neighbour

Specified by:

accept in interface LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>

Parameters:

neighbour - neighbour that was assigned

value - change in overall solution value

Returns:

true if the neighbour can be accepted (false to undo the assignment)