org.moeaframework.core.indicator
Class Hypervolume

java.lang.Object
  org.moeaframework.core.indicator.NormalizedIndicator
      org.moeaframework.core.indicator.Hypervolume

All Implemented Interfaces:

Indicator

public class Hypervolume
extends NormalizedIndicator

Hypervolume indicator. Represents the volume of objective space dominated by solutions in the approximation set.

Due to the computational burden of computing the hypervolume indicator and the various estimation algorithms available, the ability to redirect the hypervolume calculation to an external third-party executable is provided. See invokeNativeHypervolume(org.moeaframework.core.Problem, java.util.List, boolean) for details.

Field Summary

Fields inherited from class org.moeaframework.core.indicator.NormalizedIndicator

problem

Constructor Summary

Hypervolume(Problem problem, NondominatedPopulation referenceSet)
Constructs a hypervolume evaluator for the specified problem and reference set.

Method Summary

static double	calculateHypervolume(List<Solution> population, int numberOfSolutions, int numberOfObjectives) The internal, unnormalized hypervolume calculation.
double	evaluate(NondominatedPopulation approximationSet) Returns the value of this unary quality indicator given the specified non-dominated population.
protected static void	invert(Problem problem, Solution solution) Inverts the objective values since this hypervolume algorithm operates on maximization problems.
protected static double	invokeNativeHypervolume(Problem problem, List<Solution> solutions, boolean isInverted) Since hypervolume calculation is expensive, this method provides the ability to execute a native process to calculate hypervolume.

Methods inherited from class org.moeaframework.core.indicator.NormalizedIndicator

getNormalizedReferenceSet, normalize

Methods inherited from class java.lang.Object

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

Constructor Detail

Hypervolume

public Hypervolume(Problem problem,
                   NondominatedPopulation referenceSet)

Constructs a hypervolume evaluator for the specified problem and reference set.

Parameters:

problem - the problem

referenceSet - the reference set

Method Detail

invert

protected static void invert(Problem problem,
                             Solution solution)

Inverts the objective values since this hypervolume algorithm operates on maximization problems.

Parameters:

problem - the problem

solution - the solution to be inverted

calculateHypervolume

public static double calculateHypervolume(List<Solution> population,
                                          int numberOfSolutions,
                                          int numberOfObjectives)

The internal, unnormalized hypervolume calculation. While this method is public, we do not encourage its use since incorrect arguments can cause unexpected behavior. Instead, use the Hypervolume(Problem, NondominatedPopulation) constructor to create a normalizing version of the hypervolume calculation.

Parameters:

population - the population

numberOfSolutions - the number of solutions

numberOfObjectives - the number of objectives

Returns:

the hypervolume metric

evaluate

public double evaluate(NondominatedPopulation approximationSet)

Description copied from interface: Indicator

Returns the value of this unary quality indicator given the specified non-dominated population.

Parameters:

approximationSet - the non-dominated population to be evaluated

Returns:

the value of this quality indicator given the specified non-dominated population

invokeNativeHypervolume

protected static double invokeNativeHypervolume(Problem problem,
                                                List<Solution> solutions,
                                                boolean isInverted)

Since hypervolume calculation is expensive, this method provides the ability to execute a native process to calculate hypervolume. If provided, the org.moeaframework.core.indicator.native.hypervolume system property defines the command for invoking the native hypervolume executable. The command is a MessageFormat pattern with the following arguments available for use:

• {0} number of objectives
• {1} approximation set size
• {2} file containing the approximation set
• {3} file containing the reference point
• {4} the reference point, separated by spaces

Note: To avoid unnecessarily writing files, the command is first checked if the above arguments are specified. Use the exact argument string as shown above (e.g., {3}) in the command.

Parameters:

problem - the problem

solutions - the normalized and possibly inverted solutions

isInverted - true if the solutions are inverted; false otherwise

Returns:

the hypervolume value