Package ec.select

Class BestSelection

java.lang.Object
ec.BreedingSource
ec.SelectionMethod
ec.select.BestSelection
All Implemented Interfaces:
Prototype, Setup, RandomChoiceChooserD, Serializable, Cloneable
public class BestSelection extends SelectionMethod
Performs a tournament selection restricted to only the best, or worst, n indivdiuals in the population. If the best individuals, then tournament selection will prefer the better among them; if the worst individuals, then tournament selection will prefer the worse among them. The procedure for performing restriction is expensive to set up and bring down, so it's not appropriate for steady-state evolution. Like TournamentSelection, the size of the tournament can be any 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.

The tournament size can be any floating point value >= 1.0. If it is a non- integer value x then either a tournament of size ceil(x) is used (with probability x - floor(x)), else a tournament of size floor(x) is used.

Typical Number of Individuals Produced Per produce(...) call
Always 1.

Parameters

base.pick-worst
bool = true or false (default)		 (should we pick from among the worst n individuals in the tournament instead of the best n?)
base.size
double >= 1		 (the tournament size)
base.n
int > 0 		(the number of best-individuals to select from)
base.n-fraction
0.0 invalid input: '<'= double invalid input: '<' 1.0 (default is 1)		 (the number of best-individuals to select from, as a fraction of the total population)

Default Base
select.best

See Also:

  • Field Details

    • P_BEST

      public static final String P_BEST
      Default base
      See Also:

    • P_N

      public static final String P_N
      See Also:

    • P_N_FRACTION

      public static final String P_N_FRACTION
      See Also:

    • P_PICKWORST

      public static final String P_PICKWORST
      See Also:

    • P_SIZE

      public static final String P_SIZE
      See Also:

    • size

      public int size
      Base size of the tournament; this may change.

    • probabilityOfPickingSizePlusOne

      public double probabilityOfPickingSizePlusOne
      Probablity of picking the size plus one.

    • pickWorst

      public boolean pickWorst
      Do we pick the worst instead of the best?

    • sortedPop

      public int[] sortedPop
      Sorted, normalized, totalized fitnesses for the population

    • NOT_SET

      public static final int NOT_SET
      See Also:

    • bestn

      public int bestn

    • bestnFrac

      public double bestnFrac

  • Constructor Details

    • BestSelection

      public BestSelection()

  • Method Details

    • defaultBase

      public Parameter defaultBase()
      Description copied from interface: Prototype
      Returns the default base for this prototype. This should generally be implemented by building off of the static base() method on the DefaultsForm object for the prototype's package. This should be callable during setup(...).

    • setup

      public void setup(EvolutionState state, Parameter base)
      Description copied from class: BreedingSource
      Sets up the BreedingPipeline. You can use state.output.error here because the top-level caller promises to call exitIfErrors() after calling setup. Note that probability might get modified again by an external source if it doesn't normalize right.

      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}.

      Specified by:
      setup in interface Prototype
      Specified by:
      setup in interface Setup
      Overrides:
      setup in class BreedingSource
      See Also:

    • prepareToProduce

      public void prepareToProduce(EvolutionState s, int subpopulation, int thread)
      Description copied from class: SelectionMethod
      A default version of prepareToProduce which does nothing.
      Overrides:
      prepareToProduce in class SelectionMethod

    • produce

      public int produce(int subpopulation, EvolutionState state, int thread)
      Description copied from class: SelectionMethod
      An alternative form of "produce" special to Selection Methods; selects an individual from the given subpopulation and returns its position in that subpopulation.
      Specified by:
      produce in class SelectionMethod

    • finishProducing

      public void finishProducing(EvolutionState s, int subpopulation, int thread)
      Description copied from class: SelectionMethod
      A default version of finishProducing, which does nothing.
      Overrides:
      finishProducing in class SelectionMethod