ttsolver.heuristics
Class TimetableComparator

java.lang.Object
  ttsolver.heuristics.TimetableComparator

All Implemented Interfaces:

SolutionComparator

public class TimetableComparator
extends Object
implements SolutionComparator

Timetable (solution) comparator.

The quality of a solution is expressed as a weighted sum combining soft time and classroom preferences, satisfied soft group constrains and the total number of student conflicts. This allows us to express the importance of different types of soft constraints.

The solution comparator prefers a more complete solution (with a smaller number of unassigned variables) and a solution with a smaller number of perturbations among solutions with the same number of unassigned variables. If both solutions have the same number of unassigned variables and perturbations, the solution of better quality is selected.

Parameters:

Parameter	Type	Comment
Comparator.HardStudentConflictWeight	Double	Weight of hard student conflict (conflict between single-section classes)
Comparator.StudentConflictWeight	Double	Weight of student conflict
Comparator.TimePreferenceWeight	Double	Time preferences weight
Comparator.ContrPreferenceWeight	Double	Group constraint preferences weight
Comparator.RoomPreferenceWeight	Double	Room preferences weight
Comparator.UselessSlotWeight	Double	Useless slots weight
Comparator.TooBigRoomWeight	Double	Too big room weight
Comparator.DistanceInstructorPreferenceWeight	Double	Distance (of the rooms of the back-to-back classes) based instructor preferences weight
Comparator.PerturbationPenaltyWeight	Double	Perturbation penalty (see UniversalPerturbationsCounter)
Comparator.DeptSpreadPenaltyWeight	Double	Department balancing penalty (see DepartmentSpreadConstraint)

Version:

1.0

Author:

Tomáš Müller

Field Summary

static String	CONSTR_PREFERENCE_WEIGHT
static String	DEPT_SPREAD_PENALTY_WEIGHT
static String	DISTANCE_INSTRUCTOR_PREFERENCE_WEIGHT
static String	HARD_STUDENT_CONFLICT_WEIGHT
static String	PERTURBATION_PENALTY_WEIGHT
static String	ROOM_PREFERENCE_WEIGHT
protected static Logger	sLogger
static String	STUDENT_CONFLICT_WEIGHT
static String	TIME_PREFERENCE_WEIGHT
static String	TOO_BIG_ROOM_WEIGHT
static String	USELESS_SLOT_WEIGHT

Constructor Summary

TimetableComparator(DataProperties properties)

Method Summary

boolean	isBetterThanBestSolution(Solution currentSolution) Compares two solutions.
static Collection	parameters()

Methods inherited from class java.lang.Object

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

Field Detail

sLogger

protected static Logger sLogger

USELESS_SLOT_WEIGHT

public static final String USELESS_SLOT_WEIGHT

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Constant Field Values

TIME_PREFERENCE_WEIGHT

public static final String TIME_PREFERENCE_WEIGHT

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Constant Field Values

STUDENT_CONFLICT_WEIGHT

public static final String STUDENT_CONFLICT_WEIGHT

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Constant Field Values

ROOM_PREFERENCE_WEIGHT

public static final String ROOM_PREFERENCE_WEIGHT

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Constant Field Values

CONSTR_PREFERENCE_WEIGHT

public static final String CONSTR_PREFERENCE_WEIGHT

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Constant Field Values

HARD_STUDENT_CONFLICT_WEIGHT

public static final String HARD_STUDENT_CONFLICT_WEIGHT

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Constant Field Values

TOO_BIG_ROOM_WEIGHT

public static final String TOO_BIG_ROOM_WEIGHT

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Constant Field Values

DISTANCE_INSTRUCTOR_PREFERENCE_WEIGHT

public static final String DISTANCE_INSTRUCTOR_PREFERENCE_WEIGHT

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Constant Field Values

PERTURBATION_PENALTY_WEIGHT

public static final String PERTURBATION_PENALTY_WEIGHT

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Constant Field Values

DEPT_SPREAD_PENALTY_WEIGHT

public static final String DEPT_SPREAD_PENALTY_WEIGHT

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Constant Field Values

Constructor Detail

TimetableComparator

public TimetableComparator(DataProperties properties)

Method Detail

parameters

public static Collection parameters()

isBetterThanBestSolution

public boolean isBetterThanBestSolution(Solution currentSolution)

Description copied from interface: SolutionComparator

Compares two solutions. Returns true if the given solution is better than its best ever found solution (see Solution.saveBest() and Solution.restoreBest()).

Specified by:

isBetterThanBestSolution in interface SolutionComparator

Parameters:

currentSolution - given solution

Returns:

true if the given solution is better than the best ever found solution