Class BayesNet

java.lang.Object
  BayesNet

public class BayesNet
extends java.lang.Object

This class loads a Bayes net from a data file. A description of the topology of the Bayes net is stored in public fields, while the conditional probability tables are accessed using a public method. Internally, variables are identified with the integers 0, 1, 2, ..., up to (but not including) the number of variables. The values that each variable can take are also given as integers in a similar manner.

Field Summary

int[]	numParents The number of parents of each variable.
int[]	numValues The number of values that each variable can take.
int	numVariables The number of variables.
int[][]	parents The parents of each of the variables.
java.lang.String[][]	valueNames The names of the values of each variable.
java.lang.String[]	varName The names of each of the variables.

Constructor Summary

BayesNet(java.lang.String filename)
A constructor for constructing a Bayes net by reading in a description from the given data file.

Method Summary

double

getCondProb(int x, int[] vals) This method can be used to access the conditional probability table of each of the variables.

Methods inherited from class java.lang.Object

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

Field Detail

numVariables

public int numVariables

The number of variables.

varName

public java.lang.String[] varName

The names of each of the variables. varName[i] is the name of variable i.

numValues

public int[] numValues

The number of values that each variable can take. numValues[i] is the number of values that variable i can take.

valueNames

public java.lang.String[][] valueNames

The names of the values of each variable. valueNames[i][j] is the name of variable i's j-th value.

numParents

public int[] numParents

The number of parents of each variable. numParents[i] is the number of parents of variable i.

parents

public int[][] parents

The parents of each of the variables. parents[i][] is a list of the parents of variable i.

Constructor Detail

BayesNet

public BayesNet(java.lang.String filename)
         throws java.io.FileNotFoundException,
                java.io.IOException

A constructor for constructing a Bayes net by reading in a description from the given data file.

Throws:

java.io.FileNotFoundException

java.io.IOException

Method Detail

getCondProb

public double getCondProb(int x,
                          int[] vals)

This method can be used to access the conditional probability table of each of the variables. The method returns the conditional probability of a specified variable x taking a particular value, given the settings of variable x's parents. The first argument to this method is simply the variable x whose (conditional) probability is to be looked up. The second argument vals[] is an integer array of length equal to the total number of variables, where vals[i] is a provided value for variable i. Values must be provided in this array for x and for all of x's parents; all other values in this array will be ignored. The value returned by the method is the conditional probability of variable x taking the value vals[x], given that all of x's parents are set to the values specified in the vals[] array.