org.uncommons.watchmaker.framework.operators
Class BitStringCrossover

java.lang.Object
  org.uncommons.watchmaker.framework.operators.AbstractCrossover<BitString>
      org.uncommons.watchmaker.framework.operators.BitStringCrossover

All Implemented Interfaces:

EvolutionaryOperator<BitString>

public class BitStringCrossover
extends AbstractCrossover<BitString>

Cross-over with a configurable number of points (fixed or random) for bit strings.

Author:

Daniel Dyer

See Also:

BitString

Constructor Summary

BitStringCrossover()
Default is single-point cross-over, applied to all parents.

BitStringCrossover(int crossoverPoints)
Cross-over with a fixed number of cross-over points.

BitStringCrossover(int crossoverPoints, Probability crossoverProbability)
Cross-over with a fixed number of cross-over points.

BitStringCrossover(NumberGenerator<Integer> crossoverPointsVariable)
Cross-over with a variable number of cross-over points.

BitStringCrossover(NumberGenerator<Integer> crossoverPointsVariable, NumberGenerator<Probability> crossoverProbabilityVariable)
Sets up a cross-over implementation that uses a variable number of cross-over points.

Method Summary

protected List<BitString>

mate(BitString parent1, BitString parent2, int numberOfCrossoverPoints, Random rng) Perform cross-over on a pair of parents to generate a pair of offspring.

Methods inherited from class org.uncommons.watchmaker.framework.operators.AbstractCrossover

apply

Methods inherited from class java.lang.Object

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

Constructor Detail

BitStringCrossover

public BitStringCrossover()

Default is single-point cross-over, applied to all parents.

BitStringCrossover

public BitStringCrossover(int crossoverPoints)

Cross-over with a fixed number of cross-over points.

Parameters:

crossoverPoints - The constant number of cross-over points to use for all cross-over operations.

BitStringCrossover

public BitStringCrossover(int crossoverPoints,
                          Probability crossoverProbability)

Cross-over with a fixed number of cross-over points. Cross-over may or may not be applied to a given pair of parents depending on the crossoverProbability.

Parameters:

crossoverPoints - The constant number of cross-over points to use for all cross-over operations.

crossoverProbability - The probability that, once selected, a pair of parents will be subjected to cross-over rather than being copied, unchanged, into the output population.

BitStringCrossover

public BitStringCrossover(NumberGenerator<Integer> crossoverPointsVariable)

Cross-over with a variable number of cross-over points.

Parameters:

crossoverPointsVariable - A random variable that provides a number of cross-over points for each cross-over operation.

BitStringCrossover

public BitStringCrossover(NumberGenerator<Integer> crossoverPointsVariable,
                          NumberGenerator<Probability> crossoverProbabilityVariable)

Sets up a cross-over implementation that uses a variable number of cross-over points. Cross-over is applied to a proportion of selected parent pairs, with the remainder copied unchanged into the output population. The size of this evolved proportion is controlled by the crossoverProbabilityVariable parameter.

Parameters:

crossoverPointsVariable - A variable that provides a (possibly constant, possibly random) number of cross-over points for each cross-over operation.

crossoverProbabilityVariable - A variable that controls the probability that, once selected, a pair of parents will be subjected to cross-over rather than being copied, unchanged, into the output population.

Method Detail

mate

protected List<BitString> mate(BitString parent1,
                               BitString parent2,
                               int numberOfCrossoverPoints,
                               Random rng)

Perform cross-over on a pair of parents to generate a pair of offspring.

Specified by:

mate in class AbstractCrossover<BitString>

Parameters:

parent1 - One of two individuals that provides the source material for generating offspring.

parent2 - One of two individuals that provides the source material for generating offspring.

numberOfCrossoverPoints - The number of cross-overs performed on the two parents.

rng - A source of randomness used to determine the location of cross-over points.

Returns:

A list containing two evolved offspring.