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

Class FileBasedDoubleDistanceFunction

java.lang.Object

de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDatabaseDistanceFunction<DBID>

de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDBIDRangeDistanceFunction

de.lmu.ifi.dbs.elki.distance.distancefunction.external.FileBasedDoubleDistanceFunction

All Implemented Interfaces:

DBIDDistanceFunction, DBIDRangeDistanceFunction, DistanceFunction<DBID>

@Title(value="File based double distance for database objects.")
@Description(value="Loads double distance values from an external text file.")
public class FileBasedDoubleDistanceFunction
extends AbstractDBIDRangeDistanceFunction

Distance function that is based on double distances given by a distance matrix of an external ASCII file. Note: parsing an ASCII file is rather expensive. See AsciiDistanceParser for the default input format. TODO: use a double[] instead of the hash map.

Author:

Elke Achtert, Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileBasedDoubleDistanceFunction.Parameterizer Parameterization class.

Nested classes/interfaces inherited from class de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractDatabaseDistanceFunction

AbstractDatabaseDistanceFunction.Instance<O>

Field Summary

Fields

Modifier and Type	Field and Description
private TLongDoubleMap	cache The distance cache
private File	matrixfile Input file of distance matrix
private DistanceParser	parser Distance parser

Constructor Summary

Constructors

Constructor and Description
FileBasedDoubleDistanceFunction(DistanceParser parser, File matrixfile) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
double	distance(int i1, int i2) Compute the distance for two integer offsets.
boolean	equals(Object obj)
<O extends DBID> DistanceQuery<O>	instantiate(Relation<O> database) Instantiate with a database to get the actual distance query.
private void	loadCache(DistanceParser parser, File matrixfile)
protected static long	makeKey(int i1, int i2) Combine two integer ids into a long value.

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

distance, getInputTypeRestriction

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

isMetric, isSymmetric

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction

isMetric, isSymmetric

Field Detail

cache

private TLongDoubleMap cache

The distance cache

parser

private DistanceParser parser

Distance parser

matrixfile

private File matrixfile

Input file of distance matrix

Constructor Detail

FileBasedDoubleDistanceFunction

public FileBasedDoubleDistanceFunction(DistanceParser parser,
                               File matrixfile)

Constructor.

Parameters:

parser - Parser

matrixfile - input file

Method Detail

instantiate

public <O extends DBID> DistanceQuery<O> instantiate(Relation<O> database)

Description copied from interface: DistanceFunction

Instantiate with a database to get the actual distance query.

Specified by:

instantiate in interface DistanceFunction<DBID>

Overrides:

instantiate in class AbstractDBIDRangeDistanceFunction

Parameters:

database - The representation to use

Returns:

Actual distance query.

distance

public double distance(int i1,
              int i2)

Description copied from interface: DBIDRangeDistanceFunction

Compute the distance for two integer offsets.

Parameters:

i1 - First offset

i2 - Second offset

Returns:

Distance

loadCache

private void loadCache(DistanceParser parser,
             File matrixfile)
                throws IOException

Throws:

IOException

makeKey

protected static final long makeKey(int i1,
           int i2)

Combine two integer ids into a long value.

Parameters:

i1 - First id

i2 - Second id

Returns:

Combined value

equals

public boolean equals(Object obj)

Overrides:

equals in class Object