Class BNNode

java.lang.Object

BNNode

public class BNNode
extends java.lang.Object

A representation of a Bayesian network node. You should use but not modify this class.

Field Summary

Fields

Modifier and Type	Field and Description
BNNode[]	children array of node children (possibly empty)
double[]	cpt conditional probability table indexed by the binary number formed by concatenating Boolean bits from parent values (ordered by parents array), that is: parents[0].value?1:0 * 2^(p-1) + parents[1].value?1:0 * 2^(p-2) + ...
boolean	isEvidence whether or not node is an evidence node
java.lang.String	name node variable name
static java.util.ArrayList<BNNode>	nodes list of all BNNodes
BNNode[]	parents array of node parents (possibly empty)
boolean	value node variable value

Constructor Summary

Constructors

Constructor and Description
BNNode()

Method Summary

Modifier and Type	Method and Description
static void	computeChildren() Compute the children from the parents.
double	cptLookup() Returns Conditional Probability Table (CPT) entry (probability of current variable being true) corresponding to current parent node values.
static void	printBN() Print all information about the BN.
java.lang.String	toString() Return String representation of node.

Methods inherited from class java.lang.Object

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

Field Detail

nodes

public static java.util.ArrayList<BNNode> nodes

list of all BNNodes

name

public java.lang.String name

node variable name

value

public boolean value

node variable value

parents

public BNNode[] parents

array of node parents (possibly empty)

children

public BNNode[] children

array of node children (possibly empty)

cpt

public double[] cpt

conditional probability table indexed by the binary number formed by concatenating Boolean bits from parent values (ordered by parents array), that is: parents[0].value?1:0 * 2^(p-1) + parents[1].value?1:0 * 2^(p-2) + ... + parents[p-1].value?1:0 * 1

isEvidence

public boolean isEvidence

whether or not node is an evidence node

Constructor Detail

BNNode

public BNNode()

Method Detail

computeChildren

public static void computeChildren()

Compute the children from the parents. A node with no children will have an empty array.

cptLookup

public double cptLookup()

Returns Conditional Probability Table (CPT) entry (probability of current variable being true) corresponding to current parent node values. To figure the mapping from parent values to table entry, imagine parent values as digits of a binary number. (The first/last parent is the most/least significant digit.) Convert this binary number to an integer, and you have the index to the CPT.

Example: P(a|b,c) = {0.1, 0.2, 0.3, 0.4} means
         P(+a|-b -c) = 0.1   P(+a|-b +c) = 0.2   P(+a|+b -c) = 0.3   P(+a|+b +c) = 0.4
               0  0                0  1                1  0                1  1
                0                   1                   2                   3
cpt == {0.1, 0.2, 0.3, 0.4}

Returns:

double CPT entry (probability of current variable being true) corresponding to current parent node values.

printBN

public static void printBN()

Print all information about the BN.

toString

public java.lang.String toString()

Return String representation of node.

Overrides:

toString in class java.lang.Object

Returns:

java.lang.String String representation of node