public class ADF extends GPNode
In this system, the ADF facility consists of several classes: ADF, ADM, ADFStack, ADFContext, and ADFArgument. ADFs, and their cousins ADMs ("Automatically Defined Macros [Lee Spector]"), appear as typical function nodes in a GP tree. However, they have a special associated tree in the individual's tree forest which they evaluate as a kind of a "subfunction".
When an ADF is evaluated, it first evaluates all of its children and stores away their results. It then evaluates its associated tree. In the associated tree may exist one or more ADF Argument Terminals, defined by the ADFArgument class. These terminal nodes are associated with a single number which represents the "argument" in the original ADF which evaluated their tree. When an Argument Terminal is evaluated, it returns the stored result for that child number in the parent ADF. Ultimately, when the associated tree completes its evaluation, the ADF returns that value.
ADMs work slightly differently. When an ADM is evaluated, it immediately evaluates its associated tree without first evaluating any children. When an Argument Terminal is evaluated, it evaluates the subtree of the appropriate child number in the parent ADM and returns that result. These subtrees can be evaluated many times. When the associated tree completes its evaluation, the ADM returns that value.
Obviously, if you have Argument Terminals in a tree, that tree must be only callable by ADFs and ADMs, otherwise the Argument Terminals won't have anything to return. Furthermore, you must make sure that you don't have an Argument Terminal in a tree whose number is higher than the smallest arity (number of arguments) of a calling ADF or ADM.
The mechanism behind ADFs and ADMs is complex, requiring two specially- stored stacks (contained in the ADFStack object) of ADFContexts. For information on how this mechanism works, see ADFStack.
Parameters
base.tree int >= 0 |
(The "associated tree" of the ADF) |
base.name String, can be undefined |
(A simple "name" of the ADF to distinguish it from other ADF functions in your function set. Use only letters, numbers, hyphens, and underscores. Lowercase is best.) |
Default Base
gp.adf
ADFStack
,
Serialized FormModifier and Type | Field and Description |
---|---|
int |
associatedTree
The ADF's associated tree
|
String |
name
The "function name" of the ADF, to distinguish it from other GP
functions you might provide.
|
static String |
P_ADF |
static String |
P_ASSOCIATEDTREE |
static String |
P_FUNCTIONNAME |
argposition, children, CHILDREN_UNKNOWN, constraints, GPNODEPRINTTAB, MAXPRINTBYTES, NODESEARCH_ALL, NODESEARCH_CUSTOM, NODESEARCH_NONTERMINALS, NODESEARCH_TERMINALS, P_NODE, P_NODECONSTRAINTS, parent
Constructor and Description |
---|
ADF() |
Modifier and Type | Method and Description |
---|---|
void |
checkConstraints(EvolutionState state,
int tree,
GPIndividual typicalIndividual,
Parameter individualBase)
Checks type-compatibility constraints between the ADF, its argument terminals, and the tree type of its associated tree, and also checks to make sure the tree exists, there aren't invalid argument terminals in it, and there are sufficient argument terminals (a warning).
|
Parameter |
defaultBase()
The default base for GPNodes -- defined even though
GPNode is abstract so you don't have to in subclasses.
|
void |
eval(EvolutionState state,
int thread,
GPData input,
ADFStack stack,
GPIndividual individual,
Problem problem)
Evaluates the node with the given thread, state, individual, problem, and stack.
|
String |
name()
Returns a Lisp-like atom for the node and any nodes of the same class.
|
boolean |
nodeEquals(GPNode node)
Determines node equality by comparing the class, associated tree, and
function name of the nodes.
|
int |
nodeHashCode()
Returns name.hashCode() + class.hashCode() + associatedTree.
|
void |
readNode(EvolutionState state,
DataInput dataInput)
Override this to read any additional node-specific information from dataInput besides: the number of arguments,
the specific node class, the children, and the parent.
|
void |
setup(EvolutionState state,
Parameter base)
Sets up a prototypical GPNode with those features all nodes of that
prototype share, and nothing more.
|
String |
toString()
Returns a Lisp-like atom for the node which can be read in again by computer.
|
void |
writeNode(EvolutionState state,
DataOutput dataOutput)
Override this to write any additional node-specific information to dataOutput besides: the number of arguments,
the specific node class, the children, and the parent.
|
atDepth, clone, cloneReplacing, cloneReplacing, cloneReplacing, cloneReplacingAtomic, cloneReplacingAtomic, cloneReplacingNoSubclone, constraints, contains, depth, errorInfo, expectedChildren, iterator, iterator, iterator, lightClone, makeCTree, makeGraphvizSubtree, makeGraphvizTree, makeLatexTree, makeLispTree, makeLispTree, meanDepth, nodeEquivalentTo, nodeInPosition, nodeInPosition, nodeInPosition, numNodes, numNodes, parentType, pathLength, pathLength, printNode, printNode, printNode, printNodeForHumans, printNodeForHumans, printRootedTree, printRootedTree, printRootedTree, printRootedTreeForHumans, printRootedTreeForHumans, readNode, readRootedTree, readRootedTree, replaceWith, resetNode, rootedTreeEquals, rootedTreeHashCode, rootParent, swapCompatibleWith, toStringForError, toStringForHumans, verify, writeRootedTree
public static final String P_ADF
public static final String P_ASSOCIATEDTREE
public static final String P_FUNCTIONNAME
public int associatedTree
public String name
public String name()
GPNode
public Parameter defaultBase()
GPNode
defaultBase
in interface Prototype
defaultBase
in class GPNode
public void writeNode(EvolutionState state, DataOutput dataOutput) throws IOException
GPNode
writeNode
in class GPNode
IOException
public void readNode(EvolutionState state, DataInput dataInput) throws IOException
GPNode
readNode
in class GPNode
IOException
public int nodeHashCode()
nodeHashCode
in class GPNode
public boolean nodeEquals(GPNode node)
nodeEquals
in class GPNode
public void checkConstraints(EvolutionState state, int tree, GPIndividual typicalIndividual, Parameter individualBase)
checkConstraints
in class GPNode
public void setup(EvolutionState state, Parameter base)
GPNode
public String toString()
GPNode
public void eval(EvolutionState state, int thread, GPData input, ADFStack stack, GPIndividual individual, Problem problem)
GPNode
About input: input is special; it is how data is passed between parent and child nodes. If children "receive" data from their parent node when it evaluates them, they should receive this data stored in input. If (more likely) the parent "receives" results from its children, it should pass them an input object, which they'll fill out, then it should check this object for the returned value.
A tree is typically evaluated by dropping a GPData into the root. When the root returns, the resultant input should hold the return value.
In general, you should not be creating new GPDatas. If you think about it, in most conditions (excepting ADFs and ADMs) you can use and reuse input for most communications purposes between parents and children.
So, let's say that your GPNode function implements the boolean AND function,
and expects its children to return return boolean values (as it does itself).
You've implemented your GPData subclass to be, uh, BooleanData, which
looks like
public class BooleanData extends GPData
{
public boolean result;
public GPData copyTo(GPData gpd)
{
((BooleanData)gpd).result = result;
}
}
...so, you might implement your eval(...) function as follows:
public void eval(final EvolutionState state,
final int thread,
final GPData input,
final ADFStack stack,
final GPIndividual individual,
final Problem problem
{
BooleanData dat = (BooleanData)input;
boolean x;
// evaluate the first child
children[0].eval(state,thread,input,stack,individual,problem);
// store away its result
x = dat.result;
// evaluate the second child
children[1].eval(state,thread,input,stack,individual,problem);
// return (in input) the result of the two ANDed
dat.result = dat.result && x;
return;
}
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