/*
* File: AbstractDecisionTreeNode.java
* Authors: Justin Basilico
* Company: Sandia National Laboratories
* Project: Cognitive Foundry
*
* Copyright November 29, 2007, Sandia Corporation. Under the terms of Contract
* DE-AC04-94AL85000, there is a non-exclusive license for use of this work by
* or on behalf of the U.S. Government. Export of this program may require a
* license from the United States Government. See CopyrightHistory.txt for
* complete details.
*
*
*/
package gov.sandia.cognition.learning.algorithm.tree;
import gov.sandia.cognition.collection.CollectionUtil;
import gov.sandia.cognition.learning.function.categorization.Categorizer;
import gov.sandia.cognition.util.AbstractCloneableSerializable;
import gov.sandia.cognition.util.ObjectUtil;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* The {@code AbstractDecisionTreeNode} class implements common functionality
* for a decision tree node. It keeps the internal decider plus the collection
* of child nodes and the incoming label value for the node.
*
* @param <InputType> The input type of the tree.
* @param <OutputType> The output type of the tree.
* @param <InteriorType> The output of the decision at this node.
* @author Justin Basilico
* @since 2.0
*/
public abstract class AbstractDecisionTreeNode<InputType, OutputType, InteriorType>
extends AbstractCloneableSerializable
implements DecisionTreeNode<InputType, OutputType>
{
/** The parent node of this node. */
protected DecisionTreeNode<InputType, OutputType> parent;
/** The mapping of decider decision values to child nodes. For a leaf node,
* this can be null or empty. */
protected Map
<InteriorType, DecisionTreeNode<InputType, OutputType>>
childMap;
/** The decider used to make a decision as to which child use. For a
* leaf node, the decider should be null. */
protected Categorizer<? super InputType, ? extends InteriorType> decider;
/** The incoming value for the node. Usually if this is null it means that
* the node is a root node. */
protected Object incomingValue;
/**
* Creates a new instance of AbstractDecisionTreeNode
*/
public AbstractDecisionTreeNode()
{
this(null, null, null);
}
/**
* Creates a new instance of CategorizationTreeNode.
*
* @param parent The parent node of this node.
* @param decider The decision function.
* @param incomingValue The incoming value.
*/
public AbstractDecisionTreeNode(
final DecisionTreeNode<InputType, OutputType> parent,
final Categorizer<? super InputType, ? extends InteriorType> decider,
final Object incomingValue)
{
super();
this.setParent(parent);
this.setDecider(decider);
this.setChildMap(null);
this.setIncomingValue(incomingValue);
}
@Override
@SuppressWarnings("unchecked")
public AbstractDecisionTreeNode<InputType, OutputType, InteriorType>
clone()
{
final AbstractDecisionTreeNode<InputType, OutputType, InteriorType> result = (AbstractDecisionTreeNode<InputType, OutputType, InteriorType>)
super.clone();
if (this.childMap != null)
{
result.childMap = CollectionUtil.createLinkedHashMapWithSize(this.childMap.size());
for (Map.Entry<InteriorType, DecisionTreeNode<InputType, OutputType>> entry
: this.childMap.entrySet())
{
final DecisionTreeNode<InputType, OutputType> node = (DecisionTreeNode<InputType, OutputType>)
entry.getValue().clone();
if (node instanceof AbstractDecisionTreeNode)
{
// Fix the parent pointer.
((AbstractDecisionTreeNode<InputType, OutputType, ?>) node).parent = result;
}
result.childMap.put(entry.getKey(), node);
}
}
result.decider = ObjectUtil.cloneSmart(this.decider);
result.incomingValue = ObjectUtil.cloneSmart(this.incomingValue);
return result;
}
/**
* Adds a child for a given interior type.
*
* @param value The interior type value for the child.
* @param child The child node to add.
*/
public void addChild(
final InteriorType value,
final DecisionTreeNode<InputType, OutputType> child)
{
if ( this.childMap == null )
{
this.childMap = new LinkedHashMap
<InteriorType, DecisionTreeNode<InputType, OutputType>>();
}
this.childMap.put(value, child);
}
public Collection<? extends DecisionTreeNode<InputType, OutputType>> getChildren()
{
if ( this.isLeaf() )
{
return Collections.emptyList();
}
else
{
return this.childMap.values();
}
}
public boolean isLeaf()
{
return this.childMap == null || this.childMap.size() <= 0;
}
public DecisionTreeNode<InputType, OutputType> chooseChild(
final InputType input)
{
if ( this.isLeaf() || this.decider == null )
{
// Leaf nodes have no children.
return null;
}
// Apply the decider.
InteriorType decision = this.decider.evaluate(input);
if ( decision == null )
{
// No decision was made so we can't get a child node.
return null;
}
else
{
// Return the child associated with the decision, if one exists.
return this.childMap.get(decision);
}
}
public int getDepth()
{
// A node's depth is the length of the path from the node to
// the root. The root node has depth 0.
return this.parent == null ? 0 : 1 + parent.getDepth();
}
public int getTreeSize()
{
int size = 1;
for (DecisionTreeNode<?, ?> child : this.getChildren())
{
size += child.getTreeSize();
}
return size;
}
/**
* Gets the parent node for this node. Null if it is the root node.
*
* @return
* The parent node for this node.
*/
public DecisionTreeNode<InputType, OutputType> getParent()
{
return this.parent;
}
/**
* Sets the parent node for this node. Null if it is the root node.
*
* @param parent
* The parent node for this node.
*/
public void setParent(
final DecisionTreeNode<InputType, OutputType> parent)
{
this.parent = parent;
}
/**
* Gets the decider used at this node.
*
* @return The decider used.
*/
public Categorizer<? super InputType, ? extends InteriorType> getDecider()
{
return this.decider;
}
/**
* Sets the decider used at this node.
*
* @param decider The decider used.
*/
public void setDecider(
final Categorizer<? super InputType, ? extends InteriorType> decider)
{
this.decider = decider;
}
/**
* Gets the mapping of decision values to child nodes.
*
* @return The child map.
*/
public Map
<InteriorType, DecisionTreeNode<InputType, OutputType>>
getChildMap()
{
return childMap;
}
/**
* Sets the mapping of decision values to child nodes.
*
* @param childMap The child map.
*/
protected void setChildMap(
final Map
<InteriorType, DecisionTreeNode<InputType, OutputType>>
childMap)
{
this.childMap = childMap;
}
/**
* {@inheritDoc}
*
* @return {@inheritDoc}
*/
public Object getIncomingValue()
{
return this.incomingValue;
}
/**
* Sets the incoming value for the node.
*
* @param incomingValue The incoming value for the node.
*/
public void setIncomingValue(
final Object incomingValue)
{
this.incomingValue = incomingValue;
}
}