ec.es
Class MuCommaLambdaBreeder

java.lang.Object
  extended by ec.Breeder
      extended by ec.es.MuCommaLambdaBreeder
All Implemented Interfaces:
Setup, Singleton, java.io.Serializable
Direct Known Subclasses:
MuPlusLambdaBreeder

public class MuCommaLambdaBreeder
extends Breeder

MuCommaLambdaBreeder is a Breeder which, together with ESSelection, implements the (mu,lambda) breeding strategy and gathers the comparison data you can use to implement a 1/5-rule mutation mechanism.

Evolution strategies breeders require a "mu" parameter and a "lambda" parameter for each subpopulation. "mu" refers to the number of parents from which the new population will be built. "lambda" refers to the number of children generated by the mu parents. Subpopulation sizes will change as necessary to accommodate this fact in later generations. The only rule for initial subpopulation sizes is that they must be greater than or equal to the mu parameter for that subpopulation.

You can now set your initial subpopulation size to whatever you like, totally independent of lambda and mu, as long as it is >= mu.

MuCommaLambdaBreeder stores mu and lambda values for each subpopulation in the population, as well as comparisons. A comparison tells you if >1/5, <1/5 or =1/5 of the new population was better than its parents (the so-called evolution strategies "one-fifth rule". Although the comparisons are gathered, no mutation objects are provided which actually use them -- you're free to use them in any mutation objects you care to devise which requires them.

To do evolution strategies evolution, the breeding pipelines should contain at least one ESSelection selection method. While a child is being generated by the pipeline, the ESSelection object will return a parent from the pool of mu parents. The particular parent is chosen round-robin, so all the parents will have an equal number of children. It's perfectly fine to have more than one ESSelection object in the tree, or to call the same one repeatedly during the course of generating a child; all such objects will consistently return the same parent. They only increment to the nex parent in the pool of mu parents after the child has been created from the pipeline. You can also mix ESSelection operators with other operators (like Tournament Selection). But you ought to have at least one ESSelection operator in the pipeline -- else it wouldn't be Evolution Strategies, would it?

Parameters

es.lambda.subpop-num
int >= 0
Specifies the 'lambda' parameter for the subpopulation.
es.mu.subpop-num
int: a multiple of "lambda"
Specifies the 'mu' parameter for the subpopulation.

Version:
1.0
Author:
Sean Luke
See Also:
Serialized Form

Field Summary
static byte C_EXACTLY_ONE_FIFTH_BETTER
           
static byte C_OVER_ONE_FIFTH_BETTER
           
static byte C_UNDER_ONE_FIFTH_BETTER
           
 byte[] comparison
           
 int[] count
          Modified by multiple threads, don't fool with this
 int[] lambda
           
 int[] mu
           
static java.lang.String P_LAMBDA
           
static java.lang.String P_MU
           
 Population parentPopulation
           
 
Constructor Summary
MuCommaLambdaBreeder()
           
 
Method Summary
 void breedPopChunk(Population newpop, EvolutionState state, int[] numinds, int[] from, int threadnum)
          A private helper function for breedPopulation which breeds a chunk of individuals in a subpopulation for a given thread.
 Population breedPopulation(EvolutionState state)
          Breeds state.population, returning a new population.
 Population postProcess(Population newpop, Population oldpop, EvolutionState state)
          A hook for Mu+Lambda, not used in Mu,Lambda
 Population setToLambda(Population pop, EvolutionState state)
          Sets all subpopulations in pop to the expected lambda size.
 void setup(EvolutionState state, Parameter base)
          Sets up the object by reading it from the parameters stored in state, built off of the parameter base base.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

P_MU

public static final java.lang.String P_MU
See Also:
Constant Field Values

P_LAMBDA

public static final java.lang.String P_LAMBDA
See Also:
Constant Field Values

mu

public int[] mu

lambda

public int[] lambda

parentPopulation

public Population parentPopulation

comparison

public byte[] comparison

C_OVER_ONE_FIFTH_BETTER

public static final byte C_OVER_ONE_FIFTH_BETTER
See Also:
Constant Field Values

C_UNDER_ONE_FIFTH_BETTER

public static final byte C_UNDER_ONE_FIFTH_BETTER
See Also:
Constant Field Values

C_EXACTLY_ONE_FIFTH_BETTER

public static final byte C_EXACTLY_ONE_FIFTH_BETTER
See Also:
Constant Field Values

count

public int[] count
Modified by multiple threads, don't fool with this

Constructor Detail

MuCommaLambdaBreeder

public MuCommaLambdaBreeder()
Method Detail

setup

public void setup(EvolutionState state,
                  Parameter base)
Description copied from interface: Setup
Sets up the object by reading it from the parameters stored in state, built off of the parameter base base. If an ancestor implements this method, be sure to call super.setup(state,base); before you do anything else.


setToLambda

public Population setToLambda(Population pop,
                              EvolutionState state)
Sets all subpopulations in pop to the expected lambda size. Does not fill new slots with individuals.


breedPopulation

public Population breedPopulation(EvolutionState state)
Description copied from class: Breeder
Breeds state.population, returning a new population. In general, state.population should not be modified.

Specified by:
breedPopulation in class Breeder

postProcess

public Population postProcess(Population newpop,
                              Population oldpop,
                              EvolutionState state)
A hook for Mu+Lambda, not used in Mu,Lambda


breedPopChunk

public void breedPopChunk(Population newpop,
                          EvolutionState state,
                          int[] numinds,
                          int[] from,
                          int threadnum)
A private helper function for breedPopulation which breeds a chunk of individuals in a subpopulation for a given thread. Although this method is declared public (for the benefit of a private helper class in this file), you should not call it.