Package edu.cmu.tetrad.search.score

Class BdeuScore

java.lang.Object

edu.cmu.tetrad.search.score.BdeuScore

All Implemented Interfaces:

DiscreteScore, Score

public class BdeuScore
extends Object
implements DiscreteScore

Calculates the BDeu score, which the BDe (Bayes Dirichlet Equivalent) score with uniform priors. A good discussion of BD* scores can be found here:

Heckerman, D., Geiger, D. & Chickering, D.M. Learning Bayesian networks: The combination of knowledge and statistical data. Mach Learn 20, 197–243 (1995).

As for all scores in Tetrad, higher scores mean more dependence, and negative scores indicate independence.

Version:

$Id: $Id

Author:

josephramsey

See Also:

• BdeScore

Constructor Summary

Constructors

Constructor	Description
BdeuScore(DataSet dataSet)	Constructs a BDe score for the given dataset.

Method Summary

Modifier and Type	Method	Description
boolean	determines(List<Node> z, Node y)	Determines whether a set of nodes z determines a specific node y.
DataSet	getDataSet()	Retrieves the dataset associated with this BdeuScore object.
int	getMaxDegree()	Returns the maximum degree of the BDeuScore object.
double	getSamplePrior()	Returns the sample prior.
int	getSampleSize()	Returns the sample size of the data.
double	getStructurePrior()	Retrieves the structure prior associated with this BdeuScore object.
List<Node>	getVariables()	Retrieves the list of variables used in the object.
boolean	isEffectEdge(double bump)	Determines whether the bump exceeds zero.
double	localScore(int node, int[] parents)	Calculates the local score of a node given its parents.
double	localScoreDiff(int x, int y, int[] z)	Calculates the difference in local scores between two nodes y and x, when x is added to a set of nodes z.
void	setSamplePrior(double samplePrior)	Sets the sample prior for the BdeuScore object.
void	setStructurePrior(double structurePrior)	Sets the structure prior for the BdeuScore object.
String	toString()	Returns a string representation of this BDeu Score object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.cmu.tetrad.search.score.Score

append, getVariable, localScore, localScore, localScoreDiff

Constructor Details

BdeuScore

public BdeuScore(DataSet dataSet)

Constructs a BDe score for the given dataset.

Parameters:

dataSet - A discrete dataset.

Method Details

localScore

public double localScore(int node,
 int[] parents)

Calculates the local score of a node given its parents.

Specified by:

localScore in interface Score

Parameters:

node - The node.

parents - The parents of the node.

Returns:

The local score of the node.

localScoreDiff

public double localScoreDiff(int x,
 int y,
 int[] z)

Calculates the difference in local scores between two nodes y and x, when x is added to a set of nodes z.

Specified by:

localScoreDiff in interface Score

Parameters:

x - A node.

y - The node.

z - A set of nodes.

Returns:

The difference in local scores between y and x added to z.

getVariables

public List<Node> getVariables()

Retrieves the list of variables used in the object.

Specified by:

getVariables in interface Score

Returns:

A list of Node objects representing the variables used.

getSampleSize

public int getSampleSize()

Returns the sample size of the data.

Specified by:

getSampleSize in interface Score

Returns:

This size.

isEffectEdge

public boolean isEffectEdge(double bump)

Determines whether the bump exceeds zero.

Specified by:

isEffectEdge in interface Score

Parameters:

bump - The bump value.

Returns:

true if the bump is greater than zero, otherwise false.

getDataSet

public DataSet getDataSet()

Retrieves the dataset associated with this BdeuScore object.

Specified by:

getDataSet in interface DiscreteScore

Returns:

The dataset.

getStructurePrior

public double getStructurePrior()

Retrieves the structure prior associated with this BdeuScore object.

Returns:

The structure prior.

setStructurePrior

public void setStructurePrior(double structurePrior)

Sets the structure prior for the BdeuScore object.

Specified by:

setStructurePrior in interface DiscreteScore

Parameters:

structurePrior - The structure prior to be set.

getSamplePrior

public double getSamplePrior()

Returns the sample prior.

Returns:

This prior.

setSamplePrior

public void setSamplePrior(double samplePrior)

Sets the sample prior for the BdeuScore object.

Specified by:

setSamplePrior in interface DiscreteScore

Parameters:

samplePrior - The sample prior to be set.

toString

public String toString()

Returns a string representation of this BDeu Score object.

Specified by:

toString in interface Score

Overrides:

toString in class Object

Returns:

A string representation of this BDeu Score object.

getMaxDegree

public int getMaxDegree()

Returns the maximum degree of the BDeuScore object.

The maximum degree is calculated as the ceiling value of the logarithm of the sample size.

Specified by:

getMaxDegree in interface Score

Returns:

The maximum degree.

determines

public boolean determines(List<Node> z,
 Node y)

Determines whether a set of nodes z determines a specific node y.

Specified by:

determines in interface Score

Parameters:

z - The set of nodes.

y - The node to be determined.

Returns:

true if the set of nodes z determines the node y, false otherwise.

Throws:

UnsupportedOperationException - The BDeu score does not implement a 'determines' method.