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java.lang.Objectec.BreedingSource
ec.SelectionMethod
ec.select.FitProportionateSelection
ec.select.BoltzmannSelection
public class BoltzmannSelection
Similar to FitProportionateSelection, but with a Simulated Annealing style twist. BoltzmannSelection picks individuals of a population in proportion to an adjusted version of their fitnesses instead of their actual fitnesses as returned by fitness(). The adjusted fitness is calculated by e^(fitness/current_temperature) where current_temperature is a temperature value that decreases by a constant cooling rate as generations of evolution pass. The current_temperature is calculated by starting-temperature - (cooling-rate * the_current_generation_number). When the temperature dips below 1.0, annealing ceases and BoltzmannSelection reverts to normal FitProportionateSelection behavior.
Like FitProportionateSelection this is not appropriate for steady-state evolution. If you're not familiar with the relative advantages of selection methods and just want a good one, use TournamentSelection instead. Not appropriate for multiobjective fitnesses.
Note: Fitnesses must be non-negative. 0 is assumed to be the worst fitness.
Typical Number of Individuals Produced Per produce(...) call
Always 1.
Parameters
base.starting-temperature double = some large number (defaults to 1.0) |
(the starting temperature for our simulated annealing style adjusted fitness proportions) |
base.cooling-rate double = some smaller number (defaults to 0.0 which causes BoltzmannSelection to behave just as FitProportionateSelection would) |
(how slow, or fast, do you want to cool the annealing fitness proportions?) |
Default Base
select.boltzmann
Field Summary | |
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static java.lang.String |
P_BOLTZMANN
Default base |
static java.lang.String |
P_COOLING_RATE
Cooling rate parameter |
static java.lang.String |
P_STARTING_TEMPERATURE
Starting temperature parameter |
Fields inherited from class ec.select.FitProportionateSelection |
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fitnesses, P_FITNESSPROPORTIONATE |
Fields inherited from class ec.SelectionMethod |
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INDS_PRODUCED |
Fields inherited from class ec.BreedingSource |
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NO_PROBABILITY, P_PROB, probability |
Constructor Summary | |
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BoltzmannSelection()
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Method Summary | |
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Parameter |
defaultBase()
Returns the default base for this prototype. |
void |
prepareToProduce(EvolutionState s,
int subpopulation,
int thread)
A default version of prepareToProduce which does nothing. |
void |
setup(EvolutionState state,
Parameter base)
Sets up the BreedingPipeline. |
Methods inherited from class ec.select.FitProportionateSelection |
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finishProducing, produce |
Methods inherited from class ec.SelectionMethod |
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produce, produces, typicalIndsProduced |
Methods inherited from class ec.BreedingSource |
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clone, getProbability, pickRandom, preparePipeline, setProbability, setupProbabilities |
Methods inherited from class java.lang.Object |
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equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final java.lang.String P_BOLTZMANN
public static final java.lang.String P_STARTING_TEMPERATURE
public static final java.lang.String P_COOLING_RATE
Constructor Detail |
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public BoltzmannSelection()
Method Detail |
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public Parameter defaultBase()
Prototype
defaultBase
in interface Prototype
defaultBase
in class FitProportionateSelection
public void setup(EvolutionState state, Parameter base)
BreedingSource
The most common modification is to normalize it with some other set of probabilities, then set all of them up in increasing summation; this allows the use of the fast static BreedingSource-picking utility method, BreedingSource.pickRandom(...). In order to use this method, for example, if four breeding source probabilities are {0.3, 0.2, 0.1, 0.4}, then they should get normalized and summed by the outside owners as: {0.3, 0.5, 0.6, 1.0}.
setup
in interface Prototype
setup
in interface Setup
setup
in class BreedingSource
Prototype.setup(EvolutionState,Parameter)
public void prepareToProduce(EvolutionState s, int subpopulation, int thread)
SelectionMethod
prepareToProduce
in class FitProportionateSelection
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