org.jamesframework.ext.problems.objectives

Class WeightedIndex<SolutionType extends org.jamesframework.core.problems.Solution,DataType>

java.lang.Object

org.jamesframework.ext.problems.objectives.WeightedIndex<SolutionType,DataType>

Type Parameters:

SolutionType - solution type to be evaluated, required to extend Solution

DataType - underlying data type

All Implemented Interfaces:

org.jamesframework.core.problems.objectives.Objective<SolutionType,DataType>

public class WeightedIndex<SolutionType extends org.jamesframework.core.problems.Solution,DataType>
extends Object
implements org.jamesframework.core.problems.objectives.Objective<SolutionType,DataType>

An index that is composed as a weighted sum of several objectives. A weighted index is always maximizing, scores for contained minimizing objectives are negated so that maximization of the weighted sum still corresponds to minimization of these objectives.

Author:

Herman De Beukelaer

Constructor Summary

Constructors

Constructor and Description
WeightedIndex() Create an empty weighted index.

Method Summary

Modifier and Type	Method and Description
void	addObjective(org.jamesframework.core.problems.objectives.Objective<? super SolutionType,? super DataType> objective, double weight) Add an objective with corresponding weight.
<ActualSolutionType extends SolutionType> WeightedIndexEvaluation	evaluate(org.jamesframework.core.search.neigh.Move<? super ActualSolutionType> move, ActualSolutionType curSolution, org.jamesframework.core.problems.objectives.evaluations.Evaluation curEvaluation, DataType data) Delta evaluation.
WeightedIndexEvaluation	evaluate(SolutionType solution, DataType data) Produces an evaluation object that reflects the weighted sum of evaluations of all underlying objectives.
boolean	isMinimizing() Weighted index is always maximizing, so this method always returns false.
boolean	removeObjective(org.jamesframework.core.problems.objectives.Objective<? super SolutionType,? super DataType> objective) Remove an objective, if present.

Methods inherited from class java.lang.Object

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

Constructor Detail

WeightedIndex

public WeightedIndex()

Create an empty weighted index.

Method Detail

addObjective

public void addObjective(org.jamesframework.core.problems.objectives.Objective<? super SolutionType,? super DataType> objective,
                         double weight)

Add an objective with corresponding weight. Any objective designed for the solution type and data type of this multi-objective (or for more general solution or data types) can be added. The specified weight should be strictly positive, if not, an exception will be thrown.

Parameters:

objective - objective to be added

weight - corresponding weight (strictly positive)

Throws:

IllegalArgumentException - if the specified weight is not strictly positive

removeObjective

public boolean removeObjective(org.jamesframework.core.problems.objectives.Objective<? super SolutionType,? super DataType> objective)

Remove an objective, if present. Returns true if the objective has been successfully removed, false if it was not contained in the index.

Parameters:

objective - objective to remove

Returns:

true if the objective has been successfully removed

isMinimizing

public boolean isMinimizing()

Weighted index is always maximizing, so this method always returns false. Scores for contained minimizing objectives are negated, i.e. their sign is flipped.

Specified by:

isMinimizing in interface org.jamesframework.core.problems.objectives.Objective<SolutionType extends org.jamesframework.core.problems.Solution,DataType>

Returns:

false

evaluate

public WeightedIndexEvaluation evaluate(SolutionType solution,
                                        DataType data)

Produces an evaluation object that reflects the weighted sum of evaluations of all underlying objectives.

Specified by:

evaluate in interface org.jamesframework.core.problems.objectives.Objective<SolutionType extends org.jamesframework.core.problems.Solution,DataType>

Parameters:

solution - solution to evaluate

data - data to be used for evaluation

Returns:

weighted index evaluation

evaluate

public <ActualSolutionType extends SolutionType> WeightedIndexEvaluation evaluate(org.jamesframework.core.search.neigh.Move<? super ActualSolutionType> move,
                                                                                  ActualSolutionType curSolution,
                                                                                  org.jamesframework.core.problems.objectives.evaluations.Evaluation curEvaluation,
                                                                                  DataType data)

Delta evaluation. Computes a delta evaluation for each contained objective and wraps the obtained modified evaluations in a new weighted index evaluation.

Specified by:

evaluate in interface org.jamesframework.core.problems.objectives.Objective<SolutionType extends org.jamesframework.core.problems.Solution,DataType>

Type Parameters:

ActualSolutionType - the actual solution type of the problem that is being solved; a subtype of the solution types of both the objective and the applied move

Parameters:

move - move to be evaluated

curSolution - current solution of a local search

curEvaluation - evaluation of current solution

data - data to be used for evaluation

Returns:

weighted index evaluation of obtained neighbour when applying the move