Developer API

org.apache.spark.mllib.tree.model

Class Node

Object

org.apache.spark.mllib.tree.model.Node

All Implemented Interfaces:

java.io.Serializable, Logging

public class Node
extends Object
implements scala.Serializable, Logging

Node in a decision tree.

About node indexing: Nodes are indexed from 1. Node 1 is the root; nodes 2, 3 are the left, right children. Node index 0 is not used.

param: id integer node id, from 1 param: predict predicted value at the node param: impurity current node impurity param: isLeaf whether the node is a leaf param: split split to calculate left and right nodes param: leftNode left child param: rightNode right child param: stats information gain stats

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Node(int id, Predict predict, double impurity, boolean isLeaf, scala.Option<Split> split, scala.Option<Node> leftNode, scala.Option<Node> rightNode, scala.Option<InformationGainStats> stats)

Method Summary

Modifier and Type	Method and Description
static Node	apply(int nodeIndex, Predict predict, double impurity, boolean isLeaf) Construct a node with nodeIndex, predict, impurity and isLeaf parameters.
static Node	emptyNode(int nodeIndex) Return a node with the given node id (but nothing else set).
static Node	getNode(int nodeIndex, Node rootNode) Traces down from a root node to get the node with the given node index.
int	id()
double	impurity()
static int	indexToLevel(int nodeIndex) Return the level of a tree which the given node is in.
boolean	isLeaf()
static boolean	isLeftChild(int nodeIndex) Returns true if this is a left child.
static int	leftChildIndex(int nodeIndex) Return the index of the left child of this node.
scala.Option<Node>	leftNode()
static int	maxNodesInLevel(int level) Return the maximum number of nodes which can be in the given level of the tree.
static int	parentIndex(int nodeIndex) Get the parent index of the given node, or 0 if it is the root.
Predict	predict()
double	predict(Vector features) predict value if node is not leaf
static int	rightChildIndex(int nodeIndex) Return the index of the right child of this node.
scala.Option<Node>	rightNode()
scala.Option<Split>	split()
static int	startIndexInLevel(int level) Return the index of the first node in the given level.
scala.Option<InformationGainStats>	stats()
String	toString()

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.spark.internal.Logging

initializeLogging, initializeLogIfNecessary, initializeLogIfNecessary, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

Constructor Detail

Node

public Node(int id,
            Predict predict,
            double impurity,
            boolean isLeaf,
            scala.Option<Split> split,
            scala.Option<Node> leftNode,
            scala.Option<Node> rightNode,
            scala.Option<InformationGainStats> stats)

Method Detail

emptyNode

public static Node emptyNode(int nodeIndex)

Return a node with the given node id (but nothing else set).

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

apply

public static Node apply(int nodeIndex,
                         Predict predict,
                         double impurity,
                         boolean isLeaf)

Construct a node with nodeIndex, predict, impurity and isLeaf parameters. This is used in DecisionTree.findBestSplits to construct child nodes after finding the best splits for parent nodes. Other fields are set at next level.

Parameters:

nodeIndex - integer node id, from 1

predict - predicted value at the node

impurity - current node impurity

isLeaf - whether the node is a leaf

Returns:

new node instance

leftChildIndex

public static int leftChildIndex(int nodeIndex)

Return the index of the left child of this node.

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

rightChildIndex

public static int rightChildIndex(int nodeIndex)

Return the index of the right child of this node.

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

parentIndex

public static int parentIndex(int nodeIndex)

Get the parent index of the given node, or 0 if it is the root.

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

indexToLevel

public static int indexToLevel(int nodeIndex)

Return the level of a tree which the given node is in.

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

isLeftChild

public static boolean isLeftChild(int nodeIndex)

Returns true if this is a left child. Note: Returns false for the root.

Parameters:

nodeIndex - (undocumented)

Returns:

(undocumented)

maxNodesInLevel

public static int maxNodesInLevel(int level)

Return the maximum number of nodes which can be in the given level of the tree.

Parameters:

level - Level of tree (0 = root).

Returns:

(undocumented)

startIndexInLevel

public static int startIndexInLevel(int level)

Return the index of the first node in the given level.

Parameters:

level - Level of tree (0 = root).

Returns:

(undocumented)

getNode

public static Node getNode(int nodeIndex,
                           Node rootNode)

Traces down from a root node to get the node with the given node index. This assumes the node exists.

Parameters:

nodeIndex - (undocumented)

rootNode - (undocumented)

Returns:

(undocumented)

id

public int id()

predict

public Predict predict()

impurity

public double impurity()

isLeaf

public boolean isLeaf()

split

public scala.Option<Split> split()

leftNode

public scala.Option<Node> leftNode()

rightNode

public scala.Option<Node> rightNode()

stats

public scala.Option<InformationGainStats> stats()

toString

public String toString()

Overrides:

toString in class Object

predict

public double predict(Vector features)

predict value if node is not leaf

Parameters:

features - feature value

Returns:

predicted value