jbnc.util
Class CondMutualInfo

java.lang.Object
  jbnc.util.CondMutualInfo

public class CondMutualInfo

extends java.lang.Object

Estimate a joint probability distribution of three discreate variables

Since:

June 1, 1999

Author:

Jarek Sacha

Constructor Summary

CondMutualInfo(FrequencyCalc fc)
Constructor for the CondMutualInfo object

Method Summary

double[][]	get(boolean[] cond, boolean usePriors, double alphaK) Return conditional mutual information matrix I.
double[][]	getProbX() Return copy of mariginal probability of class variable, p(X).

Methods inherited from class java.lang.Object

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

Constructor Detail

CondMutualInfo

public CondMutualInfo(FrequencyCalc fc)

Constructor for the CondMutualInfo object

Parameters:

fc - Description of Parameter

Method Detail

get

public double[][] get(boolean[] cond,
                      boolean usePriors,
                      double alphaK)
               throws java.lang.Exception

Return conditional mutual information matrix I. The condition may be on the last variable, Z, in the sample data set. When both variables are conditioned on Z the following formula is used:

              ___
             \                    p(x,y|z)
  I(X;Y|Z) = /__  p(x,y,z) log ---------------
             x,y                p(x|z) p(y|z)
 

When only one variable, say X, is conditioned on Z:

              ___
             \                   p(x,y|z)
  I(X;Y|Z) = /__  p(x,y,z) log -------------
             x,y                p(x|z) p(y)
 

When neither variable is conditioned on Z:

            ___
           \                 p(x,y)
  I(X;Y) = /__  p(x,y) log -----------
           x,y              p(x) p(y)
 

Parameters:

cond - weather a variable with corresponding index is conditioned on the class variable (Z).

usePriors - Description of Parameter

alphaK - Description of Parameter

Returns:

Description of the Returned Value

Throws:

java.lang.Exception - Description of Exception

getProbX

public double[][] getProbX()
                    throws java.lang.Exception

Return copy of mariginal probability of class variable, p(X).

Returns:

The ProbX value

Throws:

java.lang.Exception - Not initialized.