Class NodeIdManager

java.lang.Object

net.bmahe.genetics4j.neat.NodeIdManager

public class NodeIdManager
extends Object

Allocates collision-safe hidden-node IDs for one semantic node layout.

A manager is intended to be shared by every chromosome in an evolving population. It tracks IDs already present in chromosomes and assigns one stable hidden-node ID to each ancestral connection innovation that is split by an add-node mutation. Consequently, homologous mutations receive the same node ID even when they occur in different genomes.

Allocation and registration methods are synchronized so a manager can safely be used by concurrent mutation workers. IDs are drawn exclusively from the layout's hidden-node range and exhaustion is reported with an IllegalStateException.

See Also:

• NodeIdManagerRegistry
• InnovationManager

Field Summary

Fields

Modifier and Type	Field	Description
private final Set<Integer>	allocatedNodeIds
private final AtomicLong	nextNodeId
private final NeatNodeLayout	nodeLayout
private final ConcurrentHashMap<Integer,Integer>	splitInnovationsByNodeId
private final ConcurrentHashMap<Integer,Integer>	splitNodeIds

Constructor Summary

Constructors

Constructor	Description
NodeIdManager(NeatNodeLayout _nodeLayout)	Creates a manager for one node layout.

Method Summary

Modifier and Type	Method	Description
private int	allocateNodeId()
int	nodeIdForSplit(int connectionInnovation)	Returns the hidden-node ID associated with splitting an ancestral connection.
void	registerExistingNodeIds(Collection<Integer> nodeIds)	Registers node IDs already present in a chromosome before new IDs are allocated.
void	registerSplit(int connectionInnovation, int nodeId)	Registers a known relationship between an ancestral connection and an existing hidden node.

Methods inherited from class Object

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

Field Details

nodeLayout

private final NeatNodeLayout nodeLayout

nextNodeId

private final AtomicLong nextNodeId

allocatedNodeIds

private final Set<Integer> allocatedNodeIds

splitNodeIds

private final ConcurrentHashMap<Integer,Integer> splitNodeIds

splitInnovationsByNodeId

private final ConcurrentHashMap<Integer,Integer> splitInnovationsByNodeId

Constructor Details

NodeIdManager

public NodeIdManager(NeatNodeLayout _nodeLayout)

Creates a manager for one node layout.

Parameters:

_nodeLayout - layout defining the external IDs and hidden-node range

Throws:

NullPointerException - if _nodeLayout is null

Method Details

nodeIdForSplit

public int nodeIdForSplit(int connectionInnovation)

Returns the hidden-node ID associated with splitting an ancestral connection.

The first call allocates an ID; subsequent calls with the same innovation return that ID.

Parameters:

connectionInnovation - non-negative connection innovation number

Returns:

the stable hidden-node ID for the split

Throws:

IllegalArgumentException - if the innovation number is negative

IllegalStateException - if the hidden-node range is exhausted

registerExistingNodeIds

public void registerExistingNodeIds(Collection<Integer> nodeIds)

Registers node IDs already present in a chromosome before new IDs are allocated.

External IDs are accepted but do not consume hidden-node allocation slots. Every other ID must belong to the layout's hidden-node range.

Parameters:

nodeIds - IDs referenced by an existing chromosome

Throws:

NullPointerException - if the collection or one of its elements is null

IllegalArgumentException - if an ID is outside the layout namespaces

registerSplit

public void registerSplit(int connectionInnovation,
 int nodeId)

Registers a known relationship between an ancestral connection and an existing hidden node.

Parameters:

connectionInnovation - non-negative connection innovation number

nodeId - hidden-node ID assigned to the split

Throws:

IllegalArgumentException - if the ID is outside the hidden range or either value conflicts with a previous registration

allocateNodeId

private int allocateNodeId()