Module io.jenetics.base

Package io.jenetics

Class ExponentialRankSelector<G extends Gene<?,G>,C extends Comparable<? super C>>

java.lang.Object

io.jenetics.ProbabilitySelector<G,C>

io.jenetics.ExponentialRankSelector<G,C>

All Implemented Interfaces:

Selector<G,C>

public final class ExponentialRankSelector<G extends Gene<?,G>,C extends Comparable<? super C>>
extends ProbabilitySelector<G,C>

An alternative to the "weak" LinearRankSelector is to assign survival probabilities to the sorted individuals using an exponential function.

,

where c must within the range [0..1).

A small value of c increases the probability of the best phenotypes to be selected. If c is set to zero, the selection probability of the best phenotype is set to one. The selection probability of all other phenotypes is zero. A value near one equalizes the selection probabilities.

This selector sorts the population in descending order while calculating the selection probabilities.

Since:

1.0

Version:

5.0

Field Summary

Fields inherited from class io.jenetics.ProbabilitySelector

_reverter, _sorted, POPULATION_COMPARATOR

Constructor Summary

Constructors

Constructor	Description
ExponentialRankSelector()	Create a new selector with the default value of 0.975.
ExponentialRankSelector(double c)	Create a new exponential rank selector.

Method Summary

Modifier and Type	Method	Description
protected double[]	probabilities(Seq<Phenotype<G,C>> population, int count)	This method sorts the population in descending order while calculating the selection probabilities.
String	toString()

Methods inherited from class io.jenetics.ProbabilitySelector

probabilities, select

Methods inherited from class java.lang.Object

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

Constructor Details

ExponentialRankSelector

public ExponentialRankSelector(double c)

Create a new exponential rank selector.

Parameters:

c - the c value

Throws:

IllegalArgumentException - if c is not within the range [0..1).

ExponentialRankSelector

public ExponentialRankSelector()

Create a new selector with the default value of 0.975.

Method Details

probabilities

protected double[] probabilities(Seq<Phenotype<G,C>> population,
 int count)

This method sorts the population in descending order while calculating the selection probabilities.

Specified by:

probabilities in class ProbabilitySelector<G extends Gene<?,G>,C extends Comparable<? super C>>

Parameters:

population - The unsorted population.

count - The number of phenotypes to select. This parameter is not needed for most implementations.

Returns:

Probability array. The returned probability array must have the length population.size() and must sum to one. The returned value is checked with assert(Math.abs(math.sum(probabilities) - 1.0) < 0.0001) in the base class.

toString

public String toString()

Overrides:

toString in class Object