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java.lang.Object | +--ec.gp.koza.KozaNodeSelector
KozaNodeSelector is a GPNodeSelector which picks nodes in trees a-la Koza I, with the addition of having a probability of always picking the root. The method divides the range 0.0...1.0 into four probability areas:
The KozaNodeSelector chooses by probability between these four situations. Then, based on the situation it has picked, it selects either a random terminal, nonterminal, root, or arbitrary node from the tree and returns it.
As the selector picks a node, it builds up some statistics information which makes it able to pick a little faster in subsequent passes. Thus if you want to reuse this selector on another tree, you need to call reset() first.
Parameters
base.terminals 0.0 <= float <= 1.0, nonterminals + terminals + root <= 1.0 |
(the probability we must pick a terminal) |
base.nonterminals 0.0 <= float <= 1.0, nonterminals + terminals + root <= 1.0 |
(the probability we must pick a nonterminal if possible) |
base.root 0.0 <= float <= 1.0, nonterminals + terminals + root <= 1.0 |
(the probability we must pick the root) |
DefaultBase
gp.koza.ns
Field Summary | |
protected GPNodeGatherer |
gatherer
Used internally to look for a node. |
int |
nodes
The number of nodes in the tree, -1 if unknown. |
float |
nonterminalProbability
The probability a nonterminal must be chosen. |
int |
nonterminals
The number of nonterminals in the tree, -1 if unknown. |
static java.lang.String |
P_NODESELECTOR
|
static java.lang.String |
P_NONTERMINAL_PROBABILITY
|
static java.lang.String |
P_ROOT_PROBABILITY
|
static java.lang.String |
P_TERMINAL_PROBABILITY
|
float |
rootProbability
The probability the root must be chosen |
float |
terminalProbability
The probability a terminal must be chosen |
int |
terminals
The number of terminals in the tree, -1 if unknown. |
Constructor Summary | |
KozaNodeSelector()
|
Method Summary | |
Parameter |
defaultBase()
Returns the default base for this prototype. |
GPNode |
pickNode(EvolutionState s,
int subpopulation,
int thread,
GPIndividual ind,
GPTree tree)
Picks a node at random from tree and returns it. |
java.lang.Object |
protoClone()
Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context. |
java.lang.Object |
protoCloneSimple()
This should be implemented in a the top-level Prototype ONLY; in fact, it should probably be declared final. |
void |
reset()
Resets the Node Selector before a new series of pickNode() if need be. |
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 |
public static final java.lang.String P_NODESELECTOR
public static final java.lang.String P_TERMINAL_PROBABILITY
public static final java.lang.String P_NONTERMINAL_PROBABILITY
public static final java.lang.String P_ROOT_PROBABILITY
public float rootProbability
public float terminalProbability
public float nonterminalProbability
public int nonterminals
public int terminals
public int nodes
protected GPNodeGatherer gatherer
Constructor Detail |
public KozaNodeSelector()
Method Detail |
public Parameter defaultBase()
Prototype
defaultBase
in interface Prototype
public java.lang.Object protoClone() throws java.lang.CloneNotSupportedException
Prototype
The question here is whether or not this means to perform a "deep" or "light" ("shallow") clone, or something in-between. You may need to deep-clone parts of your object rather than simply copying their references, depending on the situation:
Implementations.
public Object protoClone() throws CloneNotSupportedException
{
return super.clone();
}
public Object protoClone() throws CloneNotSupportedException
{
myobj = (MyObject) (super.clone());
// put your deep-cloning code here...
// ...you should use protoClone and not
// protoCloneSimple to clone subordinate objects...
return myobj;
}
public Object protoClone() throws CloneNotSupportedException
{
MyObject myobj = (MyObject)(super.protoClone());
// put your deep-cloning code here...
// ...you should use protoClone and not
// protoCloneSimple to clone subordinate objects...
return myobj;
}
If you know that your superclasses will never change their protoClone() implementations, you might try inlining them in your overridden protoClone() method. But this is dangerous (though it yields a small net increase).
In general, you want to keep your deep cloning to an absolute minimum, so that you don't have to call protoClone() but one time.
The approach taken here is the fastest that I am aware of while still permitting objects to be specified at runtime from a parameter file. It would be faster to use the "new" operator; but that would require hard-coding that we can't do. Although using java.lang.Object.clone() entails an extra layer that deals with stripping away the "protected" keyword and also wrapping the exception handling (which is a BIG hit, about three times as slow as using "new"), it's still MUCH faster than using java.lang.Class.newInstance(), and also much faster than rolling our own Clone() method.
protoClone
in interface Prototype
public final java.lang.Object protoCloneSimple()
Prototype
public final Object protoCloneSimple()
{
try { return protoClone(); }
catch (CloneNotSupportedException e)
{ throw new InternalError(); } // never happens
}
protoCloneSimple
in interface Prototype
public void setup(EvolutionState state, Parameter base)
Prototype
For prototypes, setup(...) is typically called once for the prototype instance; cloned instances do not receive the setup(...) call. setup(...) may be called more than once; the only guarantee is that it will get called at least once on an instance or some "parent" object from which it was ultimately cloned.
setup
in interface Prototype
public void reset()
GPNodeSelector
reset
in interface GPNodeSelector
public GPNode pickNode(EvolutionState s, int subpopulation, int thread, GPIndividual ind, GPTree tree)
GPNodeSelector
pickNode
in interface GPNodeSelector
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