org.uncommons.watchmaker.framework.operators
Class StringCrossover

java.lang.Object
  org.uncommons.watchmaker.framework.operators.AbstractCrossover<String>
      org.uncommons.watchmaker.framework.operators.StringCrossover

All Implemented Interfaces:

EvolutionaryOperator<String>

public class StringCrossover
extends AbstractCrossover<String>

Variable-point (fixed or random) cross-over for String candidates. This implementation assumes that all candidate Strings are the same length. If they are not, an exception will be thrown at runtime.

Author:

Daniel Dyer

Constructor Summary

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

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

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

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

StringCrossover(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<String>

mate(String parent1, String 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

StringCrossover

public StringCrossover()

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

StringCrossover

public StringCrossover(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.

StringCrossover

public StringCrossover(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.

StringCrossover

public StringCrossover(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.

StringCrossover

public StringCrossover(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<String> mate(String parent1,
                            String 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<String>

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.