opendial.bn.distribs.densityfunctions

Class KernelDensityFunction

java.lang.Object

opendial.bn.distribs.densityfunctions.KernelDensityFunction

All Implemented Interfaces:

DensityFunction

public class KernelDensityFunction
extends java.lang.Object
implements DensityFunction

Density function represented as a Gaussian kernel of data points. The distribution is more exactly a Product KDE (a multivariate extension of classical KDE).

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.logging.Logger	log

Constructor Summary

Constructors

Constructor and Description
KernelDensityFunction(java.util.Collection<double[]> points) Creates a new kernel density function with the given points
KernelDensityFunction(double[][] points) Creates a new kernel density function with the given points

Method Summary

Modifier and Type	Method and Description
KernelDensityFunction	copy() Returns a copy of the density function
java.util.Map<double[],java.lang.Double>	discretise(int nbBuckets) Returns a set of discrete values for the density function.
java.util.List<org.w3c.dom.Element>	generateXML(org.w3c.dom.Document doc) Converts the distribution to a Gaussian distribution and returns its XML representation.
double[]	getBandwidth() Returns the bandwidth defined for the KDE
double	getCDF(double... x) Returns the cumulative probability distribution for the KDE.
double	getDensity(double... x) Returns the density for the given point
int	getDimensions() Returns the dimensionality of the KDE.
double[]	getMean() Returns the mean of the KDE.
double[]	getVariance() Returns the variance of the KDE.
int	hashCode() Returns the hashcode for the function
double[]	sample() Samples from the kernel density function, first picking one of the point, and then deviating from it according to a Gaussian centered around it
java.lang.String	toString() Return a pretty print for the kernel density

Methods inherited from class java.lang.Object

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

Field Detail

log

public static final java.util.logging.Logger log

Constructor Detail

KernelDensityFunction

public KernelDensityFunction(double[][] points)

Creates a new kernel density function with the given points

Parameters:

points - the points

KernelDensityFunction

public KernelDensityFunction(java.util.Collection<double[]> points)

Creates a new kernel density function with the given points

Parameters:

points - the points

Method Detail

getBandwidth

public double[] getBandwidth()

Returns the bandwidth defined for the KDE

Returns:

the bandwidth

getDensity

public double getDensity(double... x)

Returns the density for the given point

Specified by:

getDensity in interface DensityFunction

Parameters:

x - the point

Returns:

its density

sample

public double[] sample()

Samples from the kernel density function, first picking one of the point, and then deviating from it according to a Gaussian centered around it

Specified by:

sample in interface DensityFunction

Returns:

the sampled point

discretise

public java.util.Map<double[],java.lang.Double> discretise(int nbBuckets)

Returns a set of discrete values for the density function.

Specified by:

discretise in interface DensityFunction

Parameters:

nbBuckets - the number of values to extract

Returns:

the discretised values

copy

public KernelDensityFunction copy()

Returns a copy of the density function

Specified by:

copy in interface DensityFunction

Returns:

the copy

toString

public java.lang.String toString()

Return a pretty print for the kernel density

Overrides:

toString in class java.lang.Object

Returns:

the KDE string representation

hashCode

public int hashCode()

Returns the hashcode for the function

Overrides:

hashCode in class java.lang.Object

Returns:

the hashcode

getDimensions

public int getDimensions()

Returns the dimensionality of the KDE.

Specified by:

getDimensions in interface DensityFunction

Returns:

the dimensionality

getMean

public double[] getMean()

Returns the mean of the KDE.

Specified by:

getMean in interface DensityFunction

Returns:

the mean

getVariance

public double[] getVariance()

Returns the variance of the KDE.

Specified by:

getVariance in interface DensityFunction

Returns:

the density variance

getCDF

public double getCDF(double... x)

Returns the cumulative probability distribution for the KDE.

Specified by:

getCDF in interface DensityFunction

Parameters:

x - the (possibly multivariate) point x

Returns:

the cumulative probability from 0 to x.

generateXML

public java.util.List<org.w3c.dom.Element> generateXML(org.w3c.dom.Document doc)

Converts the distribution to a Gaussian distribution and returns its XML representation.

Specified by:

generateXML in interface DensityFunction

Parameters:

doc - the XML document

Returns:

the corresponding XML elements