Package edu.cmu.tetrad.bayes

Class RowSummingExactUpdater

java.lang.Object

edu.cmu.tetrad.bayes.RowSummingExactUpdater

All Implemented Interfaces:

BayesUpdater, ManipulatingBayesUpdater, TetradSerializable, Serializable

public final class RowSummingExactUpdater
extends Object
implements ManipulatingBayesUpdater

Performs updating operations on a BayesIm by summing over cells in the joint probability table for the BayesIm. Quite flexible and fast if almost all of the variables in the Bayes net are in evidence. Can be excruciatingly slow if numVars - numVarsInEvidence is more than 15.

Version:

$Id: $Id

Author:

josephramsey

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
RowSummingExactUpdater(BayesIm bayesIm)	Constructs a new updater for the given Bayes net.
RowSummingExactUpdater(BayesIm bayesIm, Evidence evidence)	Constructs a new updater for the given Bayes net.

Method Summary

Modifier and Type	Method	Description
double[]	calculatePriorMarginals(int nodeIndex)	Calculates the prior marginal probabilities of the given node.
double[]	calculateUpdatedMarginals(int nodeIndex)	Calculates the updated marginal probabilities of the given node, given the evidence.
BayesIm	getBayesIm()	The BayesIm that this updater bases its update on.
Evidence	getEvidence()	Getter for the field evidence.
double	getJointMarginal(int[] variables, int[] values)	getJointMarginal.
BayesIm	getManipulatedBayesIm()	Getter for the field manipulatedBayesIm.
Graph	getManipulatedGraph()	getManipulatedGraph.
double	getMarginal(int variable, int value)	Returns the marginal probability of the given variable taking the given value, given the evidence.
BayesIm	getUpdatedBayesIm()	The updated BayesIm.
boolean	isJointMarginalSupported()	isJointMarginalSupported.
static RowSummingExactUpdater	serializableInstance()	Generates a simple exemplar of this class to test serialization.
void	setEvidence(Evidence evidence)	Sets new evidence for the updater.
String	toString()	Prints out the most recent marginal.

Methods inherited from class java.lang.Object

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

Constructor Details

RowSummingExactUpdater

public RowSummingExactUpdater(BayesIm bayesIm)

Constructs a new updater for the given Bayes net.

Parameters:

bayesIm - a BayesIm object

RowSummingExactUpdater

public RowSummingExactUpdater(BayesIm bayesIm,
 Evidence evidence)

Constructs a new updater for the given Bayes net.

Parameters:

bayesIm - a BayesIm object

evidence - a Evidence object

Method Details

serializableInstance

public static RowSummingExactUpdater serializableInstance()

Generates a simple exemplar of this class to test serialization.

Returns:

a RowSummingExactUpdater object

getBayesIm

public BayesIm getBayesIm()

The BayesIm that this updater bases its update on. This BayesIm is not modified; rather, a new BayesIm is created and updated.

Specified by:

getBayesIm in interface BayesUpdater

Returns:

a BayesIm object

getManipulatedBayesIm

public BayesIm getManipulatedBayesIm()

Getter for the field manipulatedBayesIm.

Specified by:

getManipulatedBayesIm in interface ManipulatingBayesUpdater

Returns:

the updated BayesIm.

getManipulatedGraph

public Graph getManipulatedGraph()

getManipulatedGraph.

Specified by:

getManipulatedGraph in interface ManipulatingBayesUpdater

Returns:

a Graph object

getUpdatedBayesIm

public BayesIm getUpdatedBayesIm()

The updated BayesIm. This is a different object from the source BayesIm.

Specified by:

getUpdatedBayesIm in interface ManipulatingBayesUpdater

Returns:

a BayesIm object

See Also:

• getBayesIm()

getEvidence

public Evidence getEvidence()

Getter for the field evidence.

Specified by:

getEvidence in interface ManipulatingBayesUpdater

Returns:

a defensive copy of the evidence.

setEvidence

public void setEvidence(Evidence evidence)

Sets new evidence for the updater. Once this is called, old updating results should not longer be available.

Sets new evidence for the updater. Once this is called, old updating results should not longer be available.

Specified by:

setEvidence in interface BayesUpdater

Specified by:

setEvidence in interface ManipulatingBayesUpdater

Parameters:

evidence - evidence

isJointMarginalSupported

public boolean isJointMarginalSupported()

isJointMarginalSupported.

Specified by:

isJointMarginalSupported in interface BayesUpdater

Returns:

a boolean

getJointMarginal

public double getJointMarginal(int[] variables,
 int[] values)

getJointMarginal.

Specified by:

getJointMarginal in interface BayesUpdater

Parameters:

variables - an array of objects

values - an array of objects

Returns:

a double

getMarginal

public double getMarginal(int variable,
 int value)

Returns the marginal probability of the given variable taking the given value, given the evidence.

Returns the updated graph. This is the graph in which all probabilities of variables conditional on their parents have been updated.

Specified by:

getMarginal in interface BayesUpdater

Specified by:

getMarginal in interface ManipulatingBayesUpdater

Parameters:

variable - variable index

value - category index

Returns:

P(variable = value | evidence), where evidence is getEvidence().

calculatePriorMarginals

public double[] calculatePriorMarginals(int nodeIndex)

Calculates the prior marginal probabilities of the given node.

Specified by:

calculatePriorMarginals in interface BayesUpdater

Parameters:

nodeIndex - node index

Returns:

P(node = value), where value is the value of the node in the Bayes net.

calculateUpdatedMarginals

public double[] calculateUpdatedMarginals(int nodeIndex)

Calculates the updated marginal probabilities of the given node, given the evidence.

Specified by:

calculateUpdatedMarginals in interface BayesUpdater

Parameters:

nodeIndex - node index

Returns:

P(node = value | evidence), where value is the value of the node in the Bayes net.

toString

public String toString()

Prints out the most recent marginal.

Overrides:

toString in class Object

Returns:

a String object