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

java.lang.Object
  de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDBIDDistanceFunction<FloatDistance>
      de.lmu.ifi.dbs.elki.distance.distancefunction.external.DiskCacheBasedFloatDistanceFunction

All Implemented Interfaces:

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

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

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

Nested Class Summary

static class

DiskCacheBasedFloatDistanceFunction.Parameterizer Parameterization class.

Field Summary

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

Constructor Summary

DiskCacheBasedFloatDistanceFunction(OnDiskUpperTriangleMatrix cache)
Constructor.

Method Summary

FloatDistance	distance(DBID id1, DBID id2) Returns the distance between the two objects specified by their objects ids.
boolean	equals(Object obj)
FloatDistance	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

FLOAT_CACHE_MAGIC

public static final int FLOAT_CACHE_MAGIC

Magic to identify double cache matrices

See Also:

Constant Field Values

FLOAT_SIZE

private static final int FLOAT_SIZE

Storage required for a float value.

See Also:

Constant Field Values

cache

private OnDiskUpperTriangleMatrix cache

The distance cache

Constructor Detail

DiskCacheBasedFloatDistanceFunction

public DiskCacheBasedFloatDistanceFunction(OnDiskUpperTriangleMatrix cache)

Constructor.

Parameters:

cache - Distance matrix

Method Detail

distance

public FloatDistance 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<FloatDistance>

Specified by:

distance in class AbstractDBIDDistanceFunction<FloatDistance>

Parameters:

id1 - first object id

id2 - second object id

Returns:

the distance between the two objects specified by their objects ids

getDistanceFactory

public FloatDistance getDistanceFactory()

Description copied from interface: DistanceFunction

Method to get the distance functions factory.

Specified by:

getDistanceFactory in interface DistanceFunction<DBID,FloatDistance>

Specified by:

getDistanceFactory in class AbstractDBIDDistanceFunction<FloatDistance>

Returns:

Factory for distance objects

equals

public boolean equals(Object obj)

Overrides:

equals in class Object