org.uncommons.watchmaker.framework
Class EvolutionUtils

java.lang.Object
  org.uncommons.watchmaker.framework.EvolutionUtils

public final class EvolutionUtils
extends Object

Utility methods used by different evolution implementations. This class exists to avoid duplication of this logic among multiple evolution implementations.

Author:

Daniel Dyer

Method Summary

static <T> PopulationData<T>	getPopulationData(List<EvaluatedCandidate<T>> evaluatedPopulation, boolean naturalFitness, int eliteCount, int iterationNumber, long startTime) Gets data about the current population, including the fittest candidate and statistics about the population as a whole.
static <T> List<TerminationCondition>	shouldContinue(PopulationData<T> data, TerminationCondition... conditions) Given data about the current population and a set of termination conditions, determines whether or not the evolution should continue.
static <T> void	sortEvaluatedPopulation(List<EvaluatedCandidate<T>> evaluatedPopulation, boolean naturalFitness) Sorts an evaluated population in descending order of fitness (descending order of fitness score for natural scores, ascending order of scores for non-natural scores).

Methods inherited from class java.lang.Object

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

Method Detail

shouldContinue

public static <T> List<TerminationCondition> shouldContinue(PopulationData<T> data,
                                                            TerminationCondition... conditions)

Given data about the current population and a set of termination conditions, determines whether or not the evolution should continue.

Type Parameters:

T - The type of entity that is being evolved.

Parameters:

data - The current state of the population.

conditions - One or more termination conditions. The evolution should not continue if any of these is satisfied.

Returns:

A list of satisfied termination conditions if the evolution has reached some pre-specified state, an empty list if the evolution should stop because of a thread interruption, or null if the evolution should continue.

sortEvaluatedPopulation

public static <T> void sortEvaluatedPopulation(List<EvaluatedCandidate<T>> evaluatedPopulation,
                                               boolean naturalFitness)

Sorts an evaluated population in descending order of fitness (descending order of fitness score for natural scores, ascending order of scores for non-natural scores).

Type Parameters:

T - The type of entity that is being evolved.

Parameters:

evaluatedPopulation - The population to be sorted (in-place).

naturalFitness - True if higher fitness scores mean fitter individuals, false otherwise.

getPopulationData

public static <T> PopulationData<T> getPopulationData(List<EvaluatedCandidate<T>> evaluatedPopulation,
                                                      boolean naturalFitness,
                                                      int eliteCount,
                                                      int iterationNumber,
                                                      long startTime)

Gets data about the current population, including the fittest candidate and statistics about the population as a whole.

Type Parameters:

T - The type of entity that is being evolved.

Parameters:

evaluatedPopulation - Population of candidate solutions with their associated fitness scores.

naturalFitness - True if higher fitness scores mean fitter individuals, false otherwise.

eliteCount - The number of candidates preserved via elitism.

iterationNumber - The zero-based index of the current generation/epoch.

startTime - The time at which the evolution began, expressed as a number of milliseconds since 00:00 on 1st January 1970.

Returns:

Statistics about the current generation of evolved individuals.