Package org.opt4j.operator.crossover

Class CrossoverDoubleUnfairAverage

java.lang.Object

org.opt4j.operator.crossover.CrossoverDouble

org.opt4j.operator.crossover.CrossoverDoubleUnfairAverage

All Implemented Interfaces:

Operator<DoubleGenotype>, Crossover<DoubleGenotype>

public class CrossoverDoubleUnfairAverage
extends CrossoverDouble

The CrossoverDoubleUnfairAverage implements the unfair average crossover proposed by Nomura and Miyhoshi, 1996.

The unfair average crossover is applied to the whole genotype, i.e., the used vector of double values. In the original work, two offspring created using

z_1 = (1 + alpha)x - alpha * y for i = 1, ..., j and
z_1 = -alpha * x + (1 + alpha)y for i = j + 1, ..., n
z_2 = (1 - alpha)x + alpha * y for i = 1, ..., j and
z_2 = alpha * x + (1 - alpha)y for i = j + 1, ..., n

for each double value in the double vector. In this implementation, one offspring is created following z_1 with a probability of 0.5 and following z_2 with a probability of 0.5, respectively. At this juncture, n is the number of variables in the vector and j a randomly chosen integer between 1 and n. The value alpha is within the range (0, 0.5).

Unlike the BLX and SBX operator, the unfair average will create offspring towards one of the parent solutions.

Field Summary

Fields

Modifier and Type	Field	Description
protected final double	alpha

Fields inherited from class org.opt4j.operator.crossover.CrossoverDouble

normalize, random

Constructor Summary

Constructors

Constructor	Description
CrossoverDoubleUnfairAverage(double alpha, NormalizeDouble normalize, Rand random)	Constructs an CrossoverDoubleUnfairAverage with an alpha value and a random number generator.

Method Summary

Modifier and Type	Method	Description
protected void	crossover(List<Double> p1, List<Double> p2, List<Double> o1, List<Double> o2)	Performs a crossover of two parent Genotypes that consist of double vectors.

Methods inherited from class org.opt4j.operator.crossover.CrossoverDouble

crossover

Methods inherited from class java.lang.Object

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

Field Details

alpha

protected final double alpha

Constructor Details

CrossoverDoubleUnfairAverage

@Inject
public CrossoverDoubleUnfairAverage(double alpha,
 NormalizeDouble normalize,
 Rand random)

Constructs an CrossoverDoubleUnfairAverage with an alpha value and a random number generator.

Parameters:

alpha - the alpha value

normalize - a normalize operator

random - the random number generator

Method Details

crossover

protected void crossover(List<Double> p1,
 List<Double> p2,
 List<Double> o1,
 List<Double> o2)

Description copied from class: CrossoverDouble

Performs a crossover of two parent Genotypes that consist of double vectors.

Specified by:

crossover in class CrossoverDouble

Parameters:

p1 - the first parent

p2 - the second parent

o1 - the first offspring

o2 - the second offspring