public class MuCommaLambdaBreeder extends Breeder
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 next 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. |
Modifier and Type | Field and Description |
---|---|
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 |
java.util.ArrayList[][] |
newIndividuals |
static java.lang.String |
P_LAMBDA |
static java.lang.String |
P_MU |
static java.lang.String |
P_MU_FRACTION |
Population |
parentPopulation |
Constructor and Description |
---|
MuCommaLambdaBreeder() |
Modifier and Type | Method and Description |
---|---|
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)
Sets all subpopulations in pop to the expected lambda size.
|
int |
maximumMuLambdaDivisor()
lambda should be no SMALLER than mu times this value.
|
Population |
postProcess(Population newpop,
Population oldpop,
EvolutionState state)
A hook for Mu+Lambda, not used in Mu,Lambda
|
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.
|
public static final java.lang.String P_MU
public static final java.lang.String P_MU_FRACTION
public static final java.lang.String P_LAMBDA
public int[] mu
public int[] lambda
public Population parentPopulation
public byte[] comparison
public static final byte C_OVER_ONE_FIFTH_BETTER
public static final byte C_UNDER_ONE_FIFTH_BETTER
public static final byte C_EXACTLY_ONE_FIFTH_BETTER
public java.util.ArrayList[][] newIndividuals
public int[] count
public int maximumMuLambdaDivisor()
public void setup(EvolutionState state, Parameter base)
Setup
public Population breedPopulation(EvolutionState state)
breedPopulation
in class Breeder
public Population postProcess(Population newpop, Population oldpop, EvolutionState state)
public void breedPopChunk(Population newpop, EvolutionState state, int[] numinds, int[] from, int threadnum)