Package elki.clustering.kmedoids

Class CLARANS.Assignment

java.lang.Object

elki.clustering.kmedoids.CLARANS.Assignment

Direct Known Subclasses:

FastCLARANS.Assignment

Enclosing class:

CLARANS<O>

protected static class CLARANS.Assignment
extends java.lang.Object

Assignment state.

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field	Description
(package private) WritableIntegerDataStore	assignment	Cluster mapping.
(package private) DistanceQuery<?>	distQ	Distance function to use.
(package private) DBIDs	ids	Ids to process.
(package private) ArrayModifiableDBIDs	medoids	Medoids
(package private) DBIDArrayMIter	miter	Medoid iterator
(package private) WritableDoubleDataStore	nearest	Distance to the nearest medoid of each point.
(package private) WritableDoubleDataStore	second	Distance to the second nearest medoid.
(package private) WritableIntegerDataStore	secondid	Medoid id of the second closest.

Constructor Summary

Constructors

Constructor	Description
Assignment(DistanceQuery<?> distQ, DBIDs ids, int k)	Constructor.

Method Summary

Modifier and Type	Method	Description
protected double	assignToNearestCluster()	Assign each point to the nearest medoid.
protected double	computeCostDifferential(DBIDRef h, int mnum, CLARANS.Assignment scratch)	Compute the reassignment cost, for one swap.
protected double	recompute(DBIDRef id, int mnum, double known, int snum, double sknown)	Recompute the assignment of one point.

Methods inherited from class java.lang.Object

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

Field Detail

ids

DBIDs ids

Ids to process.

distQ

DistanceQuery<?> distQ

Distance function to use.

nearest

WritableDoubleDataStore nearest

Distance to the nearest medoid of each point.

second

WritableDoubleDataStore second

Distance to the second nearest medoid.

assignment

WritableIntegerDataStore assignment

Cluster mapping.

secondid

WritableIntegerDataStore secondid

Medoid id of the second closest. Needs some more memory, but saves recomputations in the common case where not much changed.

medoids

ArrayModifiableDBIDs medoids

Medoids

miter

DBIDArrayMIter miter

Medoid iterator

Constructor Detail

Assignment

public Assignment(DistanceQuery<?> distQ,
                  DBIDs ids,
                  int k)

Constructor.

Parameters:

distQ - Distance query

ids - IDs to process

k - Number of medoids

Method Detail

computeCostDifferential

protected double computeCostDifferential(DBIDRef h,
                                         int mnum,
                                         CLARANS.Assignment scratch)

Compute the reassignment cost, for one swap.

Parameters:

h - Current object to swap with any medoid.

mnum - Medoid number to swap with h.

scratch - Scratch assignment to fill.

Returns:

Cost change

recompute

protected double recompute(DBIDRef id,
                           int mnum,
                           double known,
                           int snum,
                           double sknown)

Recompute the assignment of one point.

Parameters:

id - Point id

mnum - Medoid number for known distance

known - Known distance

Returns:

cost

assignToNearestCluster

protected double assignToNearestCluster()

Assign each point to the nearest medoid.

Returns:

Assignment cost