net.openai.ai.ga.selection.common
Class SelectLeastFitness

java.lang.Object
  |
  +--net.openai.ai.ga.selection.common.SelectLeastFitness

All Implemented Interfaces:

SelectionAlgorithm

public class SelectLeastFitness

extends java.lang.Object

implements SelectionAlgorithm

SelectGreatestFitness is a SelectionAlgorithm that will return a portion of the passed Population that have the least fitness. It will choose either a fixed number or a percentage.

Since:

JDK1.3

Constructor Summary

SelectLeastFitness(double goalPercentage)
Creates a new SelectGreatestFitness object for choosing the specified percentage of Cells out of the specified Population who have the least fitness.

SelectLeastFitness(int goalNumber)
Creates a new SelectLeastFitness object for choosing the specified number of Cells out of the specified Population who have the least fitness.

Method Summary

Population

selectFromPopulation(Population pop) Chooses the Cells in the specified Population with the least fitness.

Methods inherited from class java.lang.Object

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

Constructor Detail

SelectLeastFitness

public SelectLeastFitness(int goalNumber)

Creates a new SelectLeastFitness object for choosing the specified number of Cells out of the specified Population who have the least fitness.

Parameters:

goalNumber - the maximum number of Cells to allow

Throws:

ArithmeticException - on a negative goalNumber

SelectLeastFitness

public SelectLeastFitness(double goalPercentage)

Creates a new SelectGreatestFitness object for choosing the specified percentage of Cells out of the specified Population who have the least fitness. The percentage must be between 0.0 and 1.0, inclusive.

Parameters:

goalNumber - the maximum number of Cells to allow

Throws:

ArithmeticException - on a negative percentage or on a percentage greater than 1.0

Method Detail

selectFromPopulation

public Population selectFromPopulation(Population pop)

Chooses the Cells in the specified Population with the least fitness. For a fixed number, returns a maximum number depending on the size of the population, but may return fewer if the population if the population is not that large. For a percentage, returns a percentage of the population, rounded down (i.e., percentage of 10% (0.10) on a size of 25 {0.10 * 25 = 2.5} returns a maximum of 2, not three; a percentage of 10% on a size of 9 {0.10 * 9 = 0.9} will not return any objects.)

The returned population is guaranteed to return the members of the specified population such that there are no other members in that population who are less than those returned. This means that cells who tie those already in the return population are ignored when their addition would cause the size to exceed that specified. For example, if the fitness of a population was {1,1,2,3,3,3,4,5,5} and the least 4 should be returned, then the returned population will be {1,1,2,3}. The cells who have fitness 1 are kept since their addition will knock more fit members out of the list. However, the other cells of fitness 3 are ignored since their addition could not knock any other cell out.

Specified by:

selectFromPopulation in interface SelectionAlgorithm

Parameters:

pop - the Population to choose from

Returns:

a selected Population in arbitrary order