ec.gp.build

Class PTCFunctionSet

java.lang.Object

ec.gp.GPFunctionSet

ec.gp.build.PTCFunctionSet

All Implemented Interfaces:

Clique, PTCFunctionSetForm, Setup, Serializable

public class PTCFunctionSet
extends GPFunctionSet
implements PTCFunctionSetForm

PTCFunctionSet is a GPFunctionSet which adheres to PTCFunctionSetForm, and thus can be used with the PTC1 and PTC2 methods. Terminal and nonterminal probabilities for nodes used in this function set are determined by the prob parameter for the nodes' GPNodeConstraints object. That's not the greatest solution, because it could require making a lot of different GPNodeConstraints, customized for each node, but it's the best I can do for now. The nonterminalSelectionProbabilities() method computes nonterminal selection probability using the probabilities above, per type, for the size requested. If the size is small enough (smaller than CACHE_SIZE), then the result is memoized so it doesn't need to be computed again next time.

Version:

1.0

Author:

Sean Luke

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	CACHE_SIZE
double[][]	p_y cache of nonterminal selection probabilities -- dense array [size-1][type].
double[][]	q_ny nonterminal probabilities[type][thenodes], in organized form
double[][]	q_ty terminal probabilities[type][thenodes], in organized form

Fields inherited from class ec.gp.GPFunctionSet

name, nodes, nodes_h, nodesByArity, nodesByName, nonterminals, nonterminals_h, nonterminalsOverArity, nonterminalsUnderArity, P_FUNC, P_NAME, P_SIZE, terminals, terminals_h

Constructor Summary

Constructors

Constructor and Description
PTCFunctionSet()

Method Summary

Methods

Modifier and Type	Method and Description
double[]	computeNonterminalSelectionProbabilities(int expectedTreeSize)
double[]	nonterminalProbabilities(int type) Returns an organized distribution (see ec.util.RandomChoice) of likelihoods that various nonterminals in the function set will be chosen over other nonterminals with the same return type.
double[]	nonterminalSelectionProbabilities(int expectedTreeSize) Returns an array (by return type) of the probability that PTC1 must pick a nonterminal over a terminal in order to guarantee the expectedTreeSize.
void	setup(EvolutionState state, Parameter base) Must be done after GPType and GPNodeConstraints have been set up
double[]	terminalProbabilities(int type) Returns an organized distribution (see ec.util.RandomChoice) of likelihoods that various terminals in the function set will be chosen over other terminals with the same return type.

Methods inherited from class ec.gp.GPFunctionSet

functionSetFor, postProcessFunctionSet, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

q_ty

public double[][] q_ty

terminal probabilities[type][thenodes], in organized form

q_ny

public double[][] q_ny

nonterminal probabilities[type][thenodes], in organized form

CACHE_SIZE

public static final int CACHE_SIZE

See Also:

Constant Field Values

p_y

public double[][] p_y

cache of nonterminal selection probabilities -- dense array [size-1][type]. If any items are null, they're not in the dense cache.

Constructor Detail

PTCFunctionSet

public PTCFunctionSet()

Method Detail

terminalProbabilities

public double[] terminalProbabilities(int type)

Description copied from interface: PTCFunctionSetForm

Returns an organized distribution (see ec.util.RandomChoice) of likelihoods that various terminals in the function set will be chosen over other terminals with the same return type. The ordering of the array is the same as the terminals[type][...] array in GPFunctionSet.

Specified by:

terminalProbabilities in interface PTCFunctionSetForm

nonterminalProbabilities

public double[] nonterminalProbabilities(int type)

Description copied from interface: PTCFunctionSetForm

Returns an organized distribution (see ec.util.RandomChoice) of likelihoods that various nonterminals in the function set will be chosen over other nonterminals with the same return type. The ordering of the array is the same as the nonterminals[type][...] array in GPFunctionSet.

Specified by:

nonterminalProbabilities in interface PTCFunctionSetForm

setup

public void setup(EvolutionState state,
         Parameter base)

Description copied from class: GPFunctionSet

Must be done after GPType and GPNodeConstraints have been set up

Specified by:

setup in interface Setup

Overrides:

setup in class GPFunctionSet

nonterminalSelectionProbabilities

public double[] nonterminalSelectionProbabilities(int expectedTreeSize)

Description copied from interface: PTCFunctionSetForm

Returns an array (by return type) of the probability that PTC1 must pick a nonterminal over a terminal in order to guarantee the expectedTreeSize. Only used by PTC1, not by PTC2.

Specified by:

nonterminalSelectionProbabilities in interface PTCFunctionSetForm

computeNonterminalSelectionProbabilities

public double[] computeNonterminalSelectionProbabilities(int expectedTreeSize)