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/.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ExamDistributionConstraint.Context

Field Summary

Fields

Modifier and Type	Field and Description
static int	sDistDifferentDay Different day constraint type
static int	sDistDifferentPeriod Different period constraint type
static int	sDistDifferentRoom Different room constraint type
static int	sDistPrecedence Precedence constraint type
static int	sDistPrecedenceRev Precedence constraint type (reverse order)
static int	sDistSameDay Same day constraint type
static int	sDistSamePeriod Same period constraint type
static int	sDistSameRoom Same room constraint type
static String[]	sDistType Distribution type name

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, int type, boolean hard, int weight) Constructor
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
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
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
int	getType() Constraint type
String	getTypeString() Constraint type name
int	getWeight() If not hard, penalty for violation
boolean	check(ExamPlacement first, ExamPlacement second) Check assignments of the given exams
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

public static final int sDistSameRoom

Same room constraint type

See Also:

Constant Field Values

sDistDifferentRoom

public static final int sDistDifferentRoom

Different room constraint type

See Also:

Constant Field Values

sDistSamePeriod

public static final int sDistSamePeriod

Same period constraint type

See Also:

Constant Field Values

sDistDifferentPeriod

public static final int sDistDifferentPeriod

Different period constraint type

See Also:

Constant Field Values

sDistPrecedence

public static final int sDistPrecedence

Precedence constraint type

See Also:

Constant Field Values

sDistPrecedenceRev

public static final int sDistPrecedenceRev

Precedence constraint type (reverse order)

See Also:

Constant Field Values

sDistSameDay

public static final int sDistSameDay

Same day constraint type

See Also:

Constant Field Values

sDistDifferentDay

public static final int sDistDifferentDay

Different day constraint type

See Also:

Constant Field Values

sDistType

public static final String[] sDistType

Distribution type name

Constructor Detail

ExamDistributionConstraint

public ExamDistributionConstraint(long id,
                                  int 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

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

getTypeString

public String getTypeString()

Constraint type name

Returns:

constraint type name (one of sDistType)

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

public boolean check(ExamPlacement first,
                     ExamPlacement second)

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

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