Package edu.cmu.tetrad.bayes

Class ApproximateUpdater

java.lang.Object

edu.cmu.tetrad.bayes.ApproximateUpdater

All Implemented Interfaces:

BayesUpdater, ManipulatingBayesUpdater, TetradSerializable, Serializable

public final class ApproximateUpdater
extends Object
implements ManipulatingBayesUpdater

Calculates updated marginals for a Bayes net by simulating data and calculating likelihood ratios. The method is as follows. For P(A | B), enough sample points are simulated from the underlying BayesIm so that 1000 satisfy the condition B. Then the maximum likelihood estimate of condition A is calculated.

Author:

Joseph Ramsey

See Also:

• Serialized Form

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
double[]	calculatePriorMarginals(int nodeIndex)
double[]	calculateUpdatedMarginals(int nodeIndex)
BayesIm	getBayesIm()
Evidence	getEvidence()
double	getJointMarginal(int[] variables, int[] values)
BayesIm	getManipulatedBayesIm()
Graph	getManipulatedGraph()
double	getMarginal(int variable, int value)
BayesIm	getUpdatedBayesIm()
boolean	isJointMarginalSupported()
static ApproximateUpdater	serializableInstance()
void	setEvidence(Evidence evidence)	Sets new evidence for the next update operation.
String	toString()	Prints out the most recent marginal.

Methods inherited from class java.lang.Object

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

Constructor Details

ApproximateUpdater

public ApproximateUpdater(BayesIm bayesIm)

ApproximateUpdater

public ApproximateUpdater(BayesIm bayesIm,
 Evidence evidence)

Constructs a new updater for the given Bayes net.

Method Details

serializableInstance

public static ApproximateUpdater serializableInstance()

Returns:

a simple exemplar of this class to test serialization.

getBayesIm

public BayesIm getBayesIm()

Specified by:

getBayesIm in interface BayesUpdater

Returns:

the Bayes instantiated model that is being updated.

getManipulatedBayesIm

public BayesIm getManipulatedBayesIm()

Specified by:

getManipulatedBayesIm in interface ManipulatingBayesUpdater

Returns:

the Bayes instantiated model after manipulations have been applied.

getManipulatedGraph

public Graph getManipulatedGraph()

Specified by:

getManipulatedGraph in interface ManipulatingBayesUpdater

Returns:

the graph for getManipulatedBayesIm().

getUpdatedBayesIm

public BayesIm getUpdatedBayesIm()

Specified by:

getUpdatedBayesIm in interface ManipulatingBayesUpdater

Returns:

the updated Bayes IM, or null if there is no updated Bayes IM.

getEvidence

public Evidence getEvidence()

Specified by:

getEvidence in interface ManipulatingBayesUpdater

Returns:

a copy of the getModel evidence.

setEvidence

public void setEvidence(Evidence evidence)

Sets new evidence for the next update operation.

Specified by:

setEvidence in interface BayesUpdater

Specified by:

setEvidence in interface ManipulatingBayesUpdater

getMarginal

public double getMarginal(int variable,
 int value)

Specified by:

getMarginal in interface BayesUpdater

Specified by:

getMarginal in interface ManipulatingBayesUpdater

Returns:

P(variable = category | evidence) where evidence is getEvidence().

isJointMarginalSupported

public boolean isJointMarginalSupported()

Specified by:

isJointMarginalSupported in interface BayesUpdater

Returns:

true if the getJointMarginal() method is supported.

getJointMarginal

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

Specified by:

getJointMarginal in interface BayesUpdater

Returns:

the joint marginal.

calculatePriorMarginals

public double[] calculatePriorMarginals(int nodeIndex)

Specified by:

calculatePriorMarginals in interface BayesUpdater

calculateUpdatedMarginals

public double[] calculateUpdatedMarginals(int nodeIndex)

Specified by:

calculateUpdatedMarginals in interface BayesUpdater

toString

public String toString()

Prints out the most recent marginal.

Overrides:

toString in class Object