de.lmu.ifi.dbs.elki.distance.distancefunction.external
Class DiskCacheBasedDoubleDistanceFunction

java.lang.Object
  de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDBIDDistanceFunction<DoubleDistance>
      de.lmu.ifi.dbs.elki.distance.distancefunction.external.DiskCacheBasedDoubleDistanceFunction

All Implemented Interfaces:

DBIDDistanceFunction<DoubleDistance>, DistanceFunction<DBID,DoubleDistance>, InspectionUtilFrequentlyScanned, Parameterizable

@Title(value="File based double distance for database objects.")
@Description(value="Loads double distance values from an external matrix.")
public class DiskCacheBasedDoubleDistanceFunction
extends AbstractDBIDDistanceFunction<DoubleDistance>

Provides a DistanceFunction that is based on double distances given by a distance matrix of an external file.

Nested Class Summary

static class

DiskCacheBasedDoubleDistanceFunction.Parameterizer Parameterization class.

Field Summary

private OnDiskUpperTriangleMatrix	cache The distance matrix
static int	DOUBLE_CACHE_MAGIC Magic to identify double cache matrices
private static int	DOUBLE_SIZE Storage required for a double value.
static OptionID	MATRIX_ID Parameter that specifies the name of the distance matrix file.

Constructor Summary

DiskCacheBasedDoubleDistanceFunction(OnDiskUpperTriangleMatrix cache)
Constructor.

Method Summary

DoubleDistance	distance(DBID id1, DBID id2) Returns the distance between the two objects specified by their objects ids.
boolean	equals(Object obj)
DoubleDistance	getDistanceFactory() Method to get the distance functions factory.

Methods inherited from class de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDBIDDistanceFunction

getInputTypeRestriction, instantiate, isMetric, isSymmetric

Methods inherited from class java.lang.Object

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

Field Detail

MATRIX_ID

public static final OptionID MATRIX_ID

Parameter that specifies the name of the distance matrix file.

Key: -distance.matrix

DOUBLE_CACHE_MAGIC

public static final int DOUBLE_CACHE_MAGIC

Magic to identify double cache matrices

See Also:

Constant Field Values

DOUBLE_SIZE

private static final int DOUBLE_SIZE

Storage required for a double value.

See Also:

Constant Field Values

cache

private OnDiskUpperTriangleMatrix cache

The distance matrix

Constructor Detail

DiskCacheBasedDoubleDistanceFunction

public DiskCacheBasedDoubleDistanceFunction(OnDiskUpperTriangleMatrix cache)

Constructor.

Parameters:

cache - Distance matrix

Method Detail

distance

public DoubleDistance distance(DBID id1,
                               DBID id2)

Returns the distance between the two objects specified by their objects ids. If a cache is used, the distance value is looked up in the cache. If the distance does not yet exists in cache, it will be computed an put to cache. If no cache is used, the distance is computed.

Specified by:

distance in interface DBIDDistanceFunction<DoubleDistance>

Specified by:

distance in class AbstractDBIDDistanceFunction<DoubleDistance>

Parameters:

id1 - first object id

id2 - second object id

Returns:

the distance between the two objects specified by their objects ids

getDistanceFactory

public DoubleDistance getDistanceFactory()

Description copied from interface: DistanceFunction

Method to get the distance functions factory.

Specified by:

getDistanceFactory in interface DistanceFunction<DBID,DoubleDistance>

Specified by:

getDistanceFactory in class AbstractDBIDDistanceFunction<DoubleDistance>

Returns:

Factory for distance objects

equals

public boolean equals(Object obj)

Overrides:

equals in class Object