org.cpsolver.exam.model

Class ExamDistributionConstraint

java.lang.Object

org.cpsolver.ifs.model.Constraint<V,T>

org.cpsolver.ifs.assignment.context.ConstraintWithContext<Exam,ExamPlacement,ExamDistributionConstraint.Context>

org.cpsolver.exam.model.ExamDistributionConstraint

All Implemented Interfaces:

Comparable<Constraint<Exam,ExamPlacement>>, CanHoldContext, HasAssignmentContext<Exam,ExamPlacement,ExamDistributionConstraint.Context>

public class ExamDistributionConstraint
extends ConstraintWithContext<Exam,ExamPlacement,ExamDistributionConstraint.Context>

Distribution binary constraint.

The following binary distribution constraints are implemented

• Same room
• Different room
• Same period
• Different period
• Precedence
• Same day

Version:

ExamTT 1.3 (Examination Timetabling)
Copyright (C) 2008 - 2014 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/.

Author:

Tomáš Müller

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ExamDistributionConstraint.Context
static class	ExamDistributionConstraint.DistributionType
static interface	ExamDistributionConstraint.PairCheck
static interface	ExamDistributionConstraint.PeriodCheck
static interface	ExamDistributionConstraint.RoomCheck

Field Summary

Fields

Modifier and Type	Field and Description
static int	sDistSameRoom Deprecated.

Fields inherited from class org.cpsolver.ifs.model.Constraint

iConstraintListeners, iId

Fields inherited from interface org.cpsolver.ifs.assignment.context.CanHoldContext

sMaxSize

Constructor Summary

Constructors

Constructor and Description
ExamDistributionConstraint(long id, ExamDistributionConstraint.DistributionType type, boolean hard, int weight) Constructor
ExamDistributionConstraint(long id, int type, boolean hard, int weight) Deprecated. use ExamDistributionConstraint(long, DistributionType, boolean, int)
ExamDistributionConstraint(long id, String type, boolean hard, int weight) Constructor
ExamDistributionConstraint(long id, String type, String pref) Constructor

Method Summary

Modifier and Type	Method and Description
boolean	check(ExamPlacement first, ExamPlacement second) Deprecated. use ExamDistributionConstraint.DistributionType.isSatisfied(ExamPlacement, ExamPlacement)
void	computeConflicts(Assignment<Exam,ExamPlacement> assignment, ExamPlacement givenPlacement, Set<ExamPlacement> conflicts) Compute conflicts -- there is a conflict if the other variable is assigned and check(ExamPlacement, ExamPlacement) is false
int	countViolations(Assignment<Exam,ExamPlacement> assignment) Return number of all violated pairs for a soft constraint
int	countViolations(Assignment<Exam,ExamPlacement> assignment, ExamPlacement p) Return number of violated pairs for a soft constraint and the given placement
ExamDistributionConstraint.Context	createAssignmentContext(Assignment<Exam,ExamPlacement> assignment) Create a new assignment context for the given assignment.
boolean	equals(Object o) Compare with other constraint for equality
ExamDistributionConstraint.DistributionType	getDistributionType()
int	getType() Constraint type
String	getTypeString() Constraint type name
int	getWeight() If not hard, penalty for violation
boolean	inConflict(Assignment<Exam,ExamPlacement> assignment, ExamPlacement givenPlacement) Check for conflict -- there is a conflict if the other variable is assigned and check(ExamPlacement, ExamPlacement) is false
boolean	isConsistent(ExamPlacement first, ExamPlacement second) Consistency check -- check(ExamPlacement, ExamPlacement) is called
boolean	isHard() True if hard (must be satisfied), false for soft (should be satisfied)
boolean	isPeriodRelated() True if the constraint is related to periods
boolean	isRoomRelated() True if the constraint is related to rooms
boolean	isSatisfied(Assignment<Exam,ExamPlacement> assignment) Return true if this is hard constraint or this is a soft constraint without any violation
boolean	isSatisfied(Assignment<Exam,ExamPlacement> assignment, ExamPlacement p) Return true if this is hard constraint or this is a soft constraint without any violation
String	toString() String representation -- constraint type name (exam 1, exam 2)

Methods inherited from class org.cpsolver.ifs.assignment.context.ConstraintWithContext

assigned, getAssignmentContextReference, getContext, getContext, setAssignmentContextReference, setModel, unassigned

Methods inherited from class org.cpsolver.ifs.model.Constraint

addConstraintListener, addVariable, assignedVariables, compareTo, computeConflictsNoForwardCheck, constraintListeners, countAssignedVariables, countVariables, getDescription, getId, getModel, getName, hashCode, removeConstraintListener, removeVariable, variables

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

sDistSameRoom

@Deprecated
public static int sDistSameRoom

Deprecated.

Constructor Detail

ExamDistributionConstraint

public ExamDistributionConstraint(long id,
                                  ExamDistributionConstraint.DistributionType type,
                                  boolean hard,
                                  int weight)

Constructor

Parameters:

id - constraint unique id

type - constraint type

hard - true if the constraint is hard (cannot be violated)

weight - if not hard, penalty for violation

ExamDistributionConstraint

@Deprecated
public ExamDistributionConstraint(long id,
                                              int type,
                                              boolean hard,
                                              int weight)

Deprecated. use ExamDistributionConstraint(long, DistributionType, boolean, int)

Constructor

Parameters:

id - constraint unique id

type - constraint type

hard - true if the constraint is hard (cannot be violated)

weight - if not hard, penalty for violation

ExamDistributionConstraint

public ExamDistributionConstraint(long id,
                                  String type,
                                  String pref)

Constructor

Parameters:

id - constraint unique id

type - constraint type (EX_SAME_PREF, EX_SAME_ROOM, or EX_PRECEDENCE)

pref - preference (R/P for required/prohibited, or -2, -1, 0, 1, 2 for preference (from preferred to discouraged))

ExamDistributionConstraint

public ExamDistributionConstraint(long id,
                                  String type,
                                  boolean hard,
                                  int weight)

Constructor

Parameters:

id - constraint unique id

type - constraint type name

hard - true if the constraint is hard

weight - constraint penalty if violated (for soft constraint)

Method Detail

isHard

public boolean isHard()

True if hard (must be satisfied), false for soft (should be satisfied)

Overrides:

isHard in class Constraint<Exam,ExamPlacement>

Returns:

true if the constraint is hard

getWeight

public int getWeight()

If not hard, penalty for violation

Returns:

constraint penalty if violated

getType

public int getType()

Constraint type

Returns:

constraint type

getDistributionType

public ExamDistributionConstraint.DistributionType getDistributionType()

getTypeString

public String getTypeString()

Constraint type name

Returns:

constraint type name (one of ExamDistributionConstraint.DistributionType.getReference())

toString

public String toString()

String representation -- constraint type name (exam 1, exam 2)

Overrides:

toString in class Object

computeConflicts

public void computeConflicts(Assignment<Exam,ExamPlacement> assignment,
                             ExamPlacement givenPlacement,
                             Set<ExamPlacement> conflicts)

Compute conflicts -- there is a conflict if the other variable is assigned and check(ExamPlacement, ExamPlacement) is false

Specified by:

computeConflicts in class Constraint<Exam,ExamPlacement>

Parameters:

assignment - current assignment

givenPlacement - value to be assigned to its variable

conflicts - resultant set of conflicting values

inConflict

public boolean inConflict(Assignment<Exam,ExamPlacement> assignment,
                          ExamPlacement givenPlacement)

Check for conflict -- there is a conflict if the other variable is assigned and check(ExamPlacement, ExamPlacement) is false

Overrides:

inConflict in class Constraint<Exam,ExamPlacement>

Parameters:

assignment - current assignment

givenPlacement - given value

Returns:

true if there is a conflict with other assigned variables of the constraint

isConsistent

public boolean isConsistent(ExamPlacement first,
                            ExamPlacement second)

Consistency check -- check(ExamPlacement, ExamPlacement) is called

Overrides:

isConsistent in class Constraint<Exam,ExamPlacement>

Parameters:

first - a value

second - a value

Returns:

true if the constraint is ok with the assignment

check

@Deprecated
public boolean check(ExamPlacement first,
                                 ExamPlacement second)

Deprecated. use ExamDistributionConstraint.DistributionType.isSatisfied(ExamPlacement, ExamPlacement)

Check assignments of the given exams

Parameters:

first - assignment of the first exam

second - assignment of the second exam

Returns:

true, if the constraint is satisfied

equals

public boolean equals(Object o)

Compare with other constraint for equality

Overrides:

equals in class Constraint<Exam,ExamPlacement>

isSatisfied

public boolean isSatisfied(Assignment<Exam,ExamPlacement> assignment)

Return true if this is hard constraint or this is a soft constraint without any violation

Parameters:

assignment - current assignment

Returns:

true if the constraint is satisfied

isSatisfied

public boolean isSatisfied(Assignment<Exam,ExamPlacement> assignment,
                           ExamPlacement p)

Return true if this is hard constraint or this is a soft constraint without any violation

Parameters:

assignment - current assignment

p - exam assignment to be made

Returns:

true if the constraint is satisfied

countViolations

public int countViolations(Assignment<Exam,ExamPlacement> assignment,
                           ExamPlacement p)

Return number of violated pairs for a soft constraint and the given placement

Parameters:

assignment - current assignment

p - exam assignment to be made

Returns:

number of examination pairs violated

countViolations

public int countViolations(Assignment<Exam,ExamPlacement> assignment)

Return number of all violated pairs for a soft constraint

Parameters:

assignment - current assignment

Returns:

number of examination pairs violated

isRoomRelated

public boolean isRoomRelated()

True if the constraint is related to rooms

Returns:

true if the constraint is related to room placement

isPeriodRelated

public boolean isPeriodRelated()

True if the constraint is related to periods

Returns:

true if the constraint is related to period placement

createAssignmentContext

public ExamDistributionConstraint.Context createAssignmentContext(Assignment<Exam,ExamPlacement> assignment)

Description copied from interface: HasAssignmentContext

Create a new assignment context for the given assignment. If there are already some variables assigned in the value, the method should make sure that the context is appropriately initialized.

Parameters:

assignment - an assignment for which there needs to be an assignment context

Returns:

a new instance of the assignment context, filled according to the given assignment