com.epochx.core
Class GPCrossover<TYPE>

java.lang.Object
  com.epochx.core.GPCrossover<TYPE>

All Implemented Interfaces:

GenerationListener

public class GPCrossover<TYPE>
extends java.lang.Object
implements GenerationListener

This class performs the very simple task of linking together parent selection and crossover. The actual tasks of crossover and selection are performed by Crossover and ProgramSelector implementations respectively.

See Also:

Crossover, UniformPointCrossover, KozaCrossover, ProgramSelector

Constructor Summary

GPCrossover(GPModel<TYPE> model)
Constructs an instance of GPCrossover which will setup the crossover operation.

Method Summary

CandidateProgram<TYPE>[]	crossover() Selects two parents by calling getProgramSelector() on the instance of GPModel given at construction and submits them to the Crossover operator which is obtained by calling getCrossover() on the model.
int	getRevertedCount() After a crossover is made, the controlling model is requested to confirm the crossover by a call to acceptCrossover().
void	onGenerationStart() Called after each generation.

Methods inherited from class java.lang.Object

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

Constructor Detail

GPCrossover

public GPCrossover(GPModel<TYPE> model)

Constructs an instance of GPCrossover which will setup the crossover operation. Note that the actual crossover operation will be performed by the subclass of Crossover returned by the models getCrossover() method.

Parameters:

model - the GPModel which defines the Crossover operator and ProgramSelector to use to perform one act of crossover on a population.

See Also:

Crossover

Method Detail

crossover

public CandidateProgram<TYPE>[] crossover()

Selects two parents by calling getProgramSelector() on the instance of GPModel given at construction and submits them to the Crossover operator which is obtained by calling getCrossover() on the model.

After a crossover is made, the controlling model is requested to confirm the crossover by a call to acceptCrossover(). This gives the model total control over whether a crossover is allowed to proceed. If acceptCrossover() returns false then the children are discarded and two new parents are selected and attempted for crossover. The number of times the crossover was reverted before being accepted is available through a call to getRevertedCount().

Even after a crossover has been accepted by the model, it may still be prevented from proceeding if the program depth of either of the children exceeds the max depth that the model defines. In the case that the children do exceed the limit then the parents are returned as the result. This does not count towards the number of reversions.

Returns:

an array of CandidatePrograms generated through crossover. This is typically 2 child programs, but could in theory be any number as returned by the Crossover operator in use.

getRevertedCount

public int getRevertedCount()

After a crossover is made, the controlling model is requested to confirm the crossover by a call to acceptCrossover(). This gives the model total control over whether a crossover is allowed to proceed. If acceptCrossover() returns false then the children are discarded and two new parents are selected and attempted for crossover. The number of times the crossover was reverted before being accepted is available through a call to this method.

Returns:

the number of times the crossover was rejected by the model.

onGenerationStart

public void onGenerationStart()

Called after each generation. For each generation we should reset all parameters taken from the model incase they've changed. The generation event is then CONFIRMed.

Specified by:

onGenerationStart in interface GenerationListener