org.cpsolver.coursett.constraint

Class MaxHolesFlexibleConstraint

java.lang.Object

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

org.cpsolver.ifs.assignment.context.ConstraintWithContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

org.cpsolver.coursett.constraint.FlexibleConstraint

org.cpsolver.coursett.constraint.MaxHolesFlexibleConstraint

All Implemented Interfaces:

Comparable<Constraint<Lecture,Placement>>, CanHoldContext, HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>, WeakeningConstraint<Lecture,Placement>

public class MaxHolesFlexibleConstraint
extends FlexibleConstraint
implements WeakeningConstraint<Lecture,Placement>

The MaxHoles constraint limits the number of free time (holes) for an instructor on a day.
It has one parameter: a maximal amount of free time (holes) that an instructor have on a day in minutes.
Reference _MaxHoles:120_ translates to a maximum number of two hours on a day (between the first and the last class on a day).

Version:

CourseTT 1.3 (University Course Timetabling)
Copyright (C) 2013 - 2017 Tomáš Müller

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	MaxHolesFlexibleConstraint.MaxHolesFlexibleConstraintContext

Nested classes/interfaces inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

FlexibleConstraint.Block, FlexibleConstraint.FlexibleConstraintContext, FlexibleConstraint.FlexibleConstraintType, FlexibleConstraint.PlacementTimeComparator

Field Summary

Fields inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

iConstraintType, iDayOfWeekOffset, iPreciseDateComputation, iPreference, iReference, iWeeks

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
MaxHolesFlexibleConstraint(Long id, String owner, String preference, String reference)

Method Summary

Modifier and Type	Method and Description
void	computeConflicts(Assignment<Lecture,Placement> assignment, Placement value, Set<Placement> conflicts) The only method which has to be implemented by any constraint.
int	countHoles(Assignment<Lecture,Placement> assignment, int dayCode, Set<Placement> conflicts, Placement value, HashMap<Lecture,Placement> assignments, BitSet week) Count number of holes (free slots) between the given classes on given day and week.
FlexibleConstraint.FlexibleConstraintContext	createAssignmentContext(Assignment<Lecture,Placement> assignment) Create a new assignment context for the given assignment.
double	getNrViolations(Assignment<Lecture,Placement> assignment, Set<Placement> conflicts, HashMap<Lecture,Placement> assignments) Count violations, that is weekly average free time that is over the limit in hours.
boolean	isConsistent(Placement value1, Placement value2) Returns true if the given assignments are consistent respecting this constraint.
void	weaken(Assignment<Lecture,Placement> assignment) Weaken the constraint.
void	weaken(Assignment<Lecture,Placement> assignment, Placement value) Weaken the constraint enough so that it can assign the given value.

Methods inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

getCurrentPreference, getDayOfWeekOffset, getName, getOwner, getPrologPreference, getReference, getRelevantPlacements, getType, getWeeks, isHard, isPreciseDateComputation, mergeToBlocks, shareWeeksAndDay, toString

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, equals, getDescription, getId, getModel, hashCode, inConflict, removeConstraintListener, removeVariable, variables

Methods inherited from class java.lang.Object

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

Constructor Detail

MaxHolesFlexibleConstraint

public MaxHolesFlexibleConstraint(Long id,
                                  String owner,
                                  String preference,
                                  String reference)

Method Detail

countHoles

public int countHoles(Assignment<Lecture,Placement> assignment,
                      int dayCode,
                      Set<Placement> conflicts,
                      Placement value,
                      HashMap<Lecture,Placement> assignments,
                      BitSet week)

Count number of holes (free slots) between the given classes on given day and week.

Parameters:

assignment - current assignment

dayCode - representation of days in week combination

conflicts - placements to be unassigned

value - placement to be assigned

assignments - placements of variables

week - bitset representing a date pattern

Returns:

number of holes (free slots) that are over the limit

getNrViolations

public double getNrViolations(Assignment<Lecture,Placement> assignment,
                              Set<Placement> conflicts,
                              HashMap<Lecture,Placement> assignments)

Count violations, that is weekly average free time that is over the limit in hours.

Specified by:

getNrViolations in class FlexibleConstraint

Parameters:

assignment - current assignment

conflicts - placements to be unassigned

assignments - placements of variables

Returns:

weekly average free time that is over the limit in hours

computeConflicts

public void computeConflicts(Assignment<Lecture,Placement> assignment,
                             Placement value,
                             Set<Placement> conflicts)

Description copied from class: Constraint

The only method which has to be implemented by any constraint. It returns the values which needs to be unassigned in order to make this constraint consistent with the given value if it is assigned to its variable. The computed list of conflicting values is added to the given set of conflicts.

Specified by:

computeConflicts in class Constraint<Lecture,Placement>

Parameters:

assignment - current assignment

value - value to be assigned to its variable

conflicts - resultant set of conflicting values

weaken

public void weaken(Assignment<Lecture,Placement> assignment)

Description copied from interface: WeakeningConstraint

Weaken the constraint. This method is called if the constraint participates in an unassigned of a variable.

Specified by:

weaken in interface WeakeningConstraint<Lecture,Placement>

Parameters:

assignment - current assignment

isConsistent

public boolean isConsistent(Placement value1,
                            Placement value2)

Description copied from class: Constraint

Returns true if the given assignments are consistent respecting this constraint. This method is used by MAC (see MacPropagation).

Overrides:

isConsistent in class FlexibleConstraint

Parameters:

value1 - a value

value2 - a value

Returns:

true if the constraint is ok with the assignment

weaken

public void weaken(Assignment<Lecture,Placement> assignment,
                   Placement value)

Description copied from interface: WeakeningConstraint

Weaken the constraint enough so that it can assign the given value.

Specified by:

weaken in interface WeakeningConstraint<Lecture,Placement>

Parameters:

assignment - current assignment

value - a conflicting value to be assigned

createAssignmentContext

public FlexibleConstraint.FlexibleConstraintContext createAssignmentContext(Assignment<Lecture,Placement> 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.

Specified by:

createAssignmentContext in interface HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

Overrides:

createAssignmentContext in class FlexibleConstraint

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