Package moa.clusterers.dstream

Class DensityGrid

java.lang.Object

moa.AbstractMOAObject

moa.cluster.Cluster

moa.cluster.SphereCluster

moa.cluster.CFCluster

moa.clusterers.dstream.DensityGrid

All Implemented Interfaces:

java.io.Serializable, MOAObject

public class DensityGrid
extends CFCluster

Density Grids are defined in equation 3 (section 3.1) of Chen and Tu 2007 as: In D-Stream, we partition the d−dimensional space S into density grids. Suppose for each dimension, its space Si, i =1, ··· ,d is divided into pi partitions as Si = Si,1 U Si,2 U ··· U Si,pi (2) then the data space S is partitioned into N = PRODUCT (i=1..d) pi density grids. For a density grid g that is composed of S1,j1 ×S2,j2 ···×Sd,jd , ji =1, ...,pi, we denote it as g =(j1,j2, ··· ,jd). (3) Citation: Y. Chen and L. Tu, “Density-Based Clustering for Real-Time Stream Data,” in Proceedings of the 13th ACM SIGKDD international conference on Knowledge discovery and data mining, 2007, pp. 133–142.

See Also:

Serialized Form

Field Summary

Fields inherited from class moa.cluster.CFCluster

LS, N, radiusFactor, SS

Constructor Summary

Constructors

Constructor	Description
DensityGrid(int[] c)	A constructor method for a density grid
DensityGrid(DensityGrid dg)	A constructor method for a density grid

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.Object o)	Overrides Object's method equals to declare that two DensityGrids are equal iff their dimensions are the same and each of their corresponding coordinates are the same.
CFCluster	getCF()	Returns a reference to the DensityGrid.
int[]	getCoordinates()
int	getDimensions()
double	getInclusionProbability(Instance instance)	Provides the probability of the argument instance belonging to the density grid in question.
java.util.ArrayList<DensityGrid>	getNeighbours()	Generates an Array List of neighbours for this density grid by varying each coordinate by one in either direction.
double	getRadius()	Provides the radius of a density grid.
int	hashCode()	Overrides Object's method hashCode to generate a hashCode for DensityGrids based on their coordinates.
boolean	isVisited()
void	setVisited(boolean isVisited)
java.lang.String	toString()	Returns a description of the object.

Methods inherited from class moa.AbstractMOAObject

copy, copy, measureByteSize, measureByteSize

Methods inherited from class moa.cluster.CFCluster

add, addVectors, getCenter, getN, getWeight, setN

Methods inherited from class moa.cluster.Cluster

getDescription, getGroundTruth, getId, getInfo, getMeasureValue, isGroundTruth, setGroundTruth, setId, setMeasureValue, setMeasureValue

Methods inherited from class java.lang.Object

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

Methods inherited from class moa.cluster.SphereCluster

combine, getCenterDistance, getCenterDistance, getClusterSpecificInfo, getDistanceVector, getDistanceVector, getHullDistance, merge, overlapRadiusDegree, overlapSave, sample, setCenter, setRadius, setWeight

Constructor Detail

DensityGrid

public DensityGrid(int[] c)

A constructor method for a density grid

Parameters:

c - the coordinates of the density grid

DensityGrid

public DensityGrid(DensityGrid dg)

A constructor method for a density grid

Parameters:

dg - the density grid to copy

Method Detail

equals

public boolean equals(java.lang.Object o)

Overrides Object's method equals to declare that two DensityGrids are equal iff their dimensions are the same and each of their corresponding coordinates are the same.

Overrides:

equals in class java.lang.Object

Parameters:

o - the object being compared for equality

Returns:

TRUE if the objects being compared are equal; FALSE otherwise

hashCode

public int hashCode()

Overrides Object's method hashCode to generate a hashCode for DensityGrids based on their coordinates.

Overrides:

hashCode in class java.lang.Object

Returns:

hc the Object's hash code

getNeighbours

public java.util.ArrayList<DensityGrid> getNeighbours()

Generates an Array List of neighbours for this density grid by varying each coordinate by one in either direction. Does not test whether the generated neighbours are valid as DensityGrid is not aware of the number of partitions in each dimension.

Returns:

an Array List of neighbours for this density grid

getCoordinates

public int[] getCoordinates()

Returns:

coordinates the coordinates of the density grid

getDimensions

public int getDimensions()

Returns:

dimensions the number of dimensions for the density grid

toString

public java.lang.String toString()

Description copied from class: AbstractMOAObject

Returns a description of the object.

Overrides:

toString in class AbstractMOAObject

Returns:

a String listing each coordinate of the density grid

getCF

public CFCluster getCF()

Returns a reference to the DensityGrid.

Specified by:

getCF in class CFCluster

Returns:

this density grid.

getInclusionProbability

public double getInclusionProbability(Instance instance)

Provides the probability of the argument instance belonging to the density grid in question.

Specified by:

getInclusionProbability in class CFCluster

Returns:

1.0 if the instance equals the density grid's coordinates; 0.0 otherwise.

getRadius

public double getRadius()

Provides the radius of a density grid.

Specified by:

getRadius in class CFCluster

Returns:

1.0, approximating a unit hypercube of dimension d.

isVisited

public boolean isVisited()

Returns:

the isVisited

setVisited

public void setVisited(boolean isVisited)

Parameters:

isVisited - the isVisited to set