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java.lang.Object | +--ec.BreedingSource | +--ec.SelectionMethod | +--ec.parsimony.BucketTournament
Does a tournament selection, limited to the subpopulation it's working in at the time.
Bucket Lexicographic Tournament selection works like as follows. There is a number of buckets (num-buckets) specified beforehand, and each is assigned a rank from 1 to num-buckets. The population, of size pop-size, is sorted by fitness. The bottom pop-size/num-buckets individuals are placed in the worst ranked bucket, plus any individuals remaining in the population with the same fitness as the best individual in the bucket. Then the second worst pop-size/num-buckets individuals are placed in the second worst ranked bucket, plus any individuals in the population equal in fitness to the best individual in that bucket. This continues until there are no individuals in the population. Note that the topmost bucket with individuals can hold fewer than pop-size/num-buckets individuals, if pop-size is not a multiple of num-buckets. Depending on the number of equal-fitness individuals in the population, there can be some top buckets that are never filled. The fitness of each individual in a bucket is set to the rank of the bucket holding it. Direct bucketing has the effect of trading off fitness differences for size. Thus the larger the bucket, the stronger the emphasis on size as a secondary objective. After ranking the individuals, size individuals are chosen at random from the population. Of those individuals, the one with the highest rank is selected. If the two individuals are in the same rank, meaning that they have similar fitness, the one with the smallest size is selected.
Bucket Lexicographic Tournament selection is so simple that it doesn't need to maintain a cache of any form, so many of the SelectionMethod methods just don't do anything at all.
Typical Number of Individuals Produced Per produce(...) call
Always 1.
Parameters
base.size int >= 1 (default 7) |
(the tournament size) |
base.pick-worst bool = true or false (default) |
(should we pick the worst individual in the tournament instead of the best?) |
base.num-buckets int >= 1 (default 10) |
(the number of buckets) |
Default Base
select.bucket-tournament
Field Summary | |
static int |
DEFAULT_SIZE
Default size |
static int |
N_BUCKETS_DEFAULT
Default number of buckets |
static java.lang.String |
P_BUCKETS
The number of buckets |
static java.lang.String |
P_PICKWORST
If the worst individual should be picked in the tournament |
static java.lang.String |
P_SIZE
Tournament size parameter |
static java.lang.String |
P_TOURNAMENT
Default base |
boolean |
pickWorst
Do we pick the worst instead of the best? |
int |
size
Size of the tournament |
Fields inherited from class ec.SelectionMethod |
INDS_PRODUCED |
Fields inherited from class ec.BreedingSource |
CHECKBOUNDARY, DEFAULT_PRODUCED, NO_PROBABILITY, P_PROB, probability, UNUSED |
Constructor Summary | |
BucketTournament()
|
Method Summary | |
Parameter |
defaultBase()
Returns the default base for this prototype. |
void |
individualReplaced(SteadyStateEvolutionState state,
int subpopulation,
int thread,
int individual)
Called whenever an individual has been replaced by another in the population. |
void |
prepareToProduce(EvolutionState state,
int subpopulation,
int thread)
Prepare to produce: create the buckets!!!! |
int |
produce(int subpopulation,
EvolutionState state,
int thread)
An alternative form of "produce" special to Selection Methods; selects an individual from the given subpopulation and returns its position in that subpopulation. |
void |
setup(EvolutionState state,
Parameter base)
Sets up the BreedingPipeline. |
void |
sourcesAreProperForm(SteadyStateEvolutionState state)
Issue an error (not a fatal -- we guarantee that callers of this method will also call exitIfErrors) if any of your sources, or their sources, etc., are not of SteadyStateBSourceForm. |
Methods inherited from class ec.SelectionMethod |
finishProducing, preparePipeline, produce, produces, typicalIndsProduced |
Methods inherited from class ec.BreedingSource |
getProbability, pickRandom, protoClone, protoCloneSimple, setProbability, setupProbabilities |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final java.lang.String P_TOURNAMENT
public static final java.lang.String P_PICKWORST
public static final java.lang.String P_SIZE
public static final int DEFAULT_SIZE
public static final java.lang.String P_BUCKETS
public static final int N_BUCKETS_DEFAULT
public int size
public boolean pickWorst
Constructor Detail |
public BucketTournament()
Method Detail |
public Parameter defaultBase()
Prototype
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 class BreedingSource
ec.BreedingSource
Prototype.setup(EvolutionState,Parameter)
public void prepareToProduce(EvolutionState state, int subpopulation, int thread)
prepareToProduce
in class SelectionMethod
public int produce(int subpopulation, EvolutionState state, int thread)
SelectionMethod
produce
in class SelectionMethod
public void individualReplaced(SteadyStateEvolutionState state, int subpopulation, int thread, int individual)
SteadyStateBSourceForm
individualReplaced
in interface SteadyStateBSourceForm
public void sourcesAreProperForm(SteadyStateEvolutionState state)
SteadyStateBSourceForm
sourcesAreProperForm
in interface SteadyStateBSourceForm
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