Package elki.clustering.kmedoids

Class FastPAM.Instance

java.lang.Object

elki.clustering.kmedoids.PAM.Instance

elki.clustering.kmedoids.FastPAM1.Instance

elki.clustering.kmedoids.FastPAM.Instance

Direct Known Subclasses:

FasterPAM.Instance

Enclosing class:

FastPAM<O>

protected static class FastPAM.Instance
extends FastPAM1.Instance

Instance for a single dataset.

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field	Description
protected double	fastswap	Tolerance for fast swapping behavior (may perform worse swaps).

Fields inherited from class elki.clustering.kmedoids.PAM.Instance

assignment, distQ, ids, nearest, second

Constructor Summary

Constructors

Constructor	Description
Instance(DistanceQuery<?> distQ, DBIDs ids, WritableIntegerDataStore assignment, double fasttol)	Constructor.

Method Summary

Modifier and Type	Method	Description
protected double	computeReassignmentCost(DBIDRef h, int mnum)	Compute the reassignment cost of one swap.
protected void	findBestSwaps(DBIDArrayIter m, ArrayModifiableDBIDs bestids, double[] best, double[] cost, double[] pcost)	Find the best swaps.
protected double	run(ArrayModifiableDBIDs medoids, int maxiter)	Run the PAM optimization phase.

Methods inherited from class elki.clustering.kmedoids.FastPAM1.Instance

assignToNearestCluster, computeReassignmentCost, updateAssignment, updatePriorCost, updateSecondNearest

Methods inherited from class java.lang.Object

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

Field Detail

fastswap

protected double fastswap

Tolerance for fast swapping behavior (may perform worse swaps).

Constructor Detail

Instance

public Instance(DistanceQuery<?> distQ,
                DBIDs ids,
                WritableIntegerDataStore assignment,
                double fasttol)

Constructor.

Parameters:

distQ - Distance query

ids - IDs to process

assignment - Cluster assignment

fasttol - Tolerance for fast swapping

Method Detail

run

protected double run(ArrayModifiableDBIDs medoids,
                     int maxiter)

Run the PAM optimization phase.

Overrides:

run in class FastPAM1.Instance

Parameters:

medoids - Medoids list

maxiter -

Returns:

final cost

findBestSwaps

protected void findBestSwaps(DBIDArrayIter m,
                             ArrayModifiableDBIDs bestids,
                             double[] best,
                             double[] cost,
                             double[] pcost)

Find the best swaps.

Parameters:

m - Medoids

bestids - Storage for best non-medois

best - Storage for best cost

cost - Scratch space for cost

computeReassignmentCost

protected double computeReassignmentCost(DBIDRef h,
                                         int mnum)

Compute the reassignment cost of one swap.

This differs from the version in regular PAM by the bit mask operation only.

Overrides:

computeReassignmentCost in class PAM.Instance

Parameters:

h - Current object to swap with the medoid

mnum - Medoid number to be replaced

Returns:

cost