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

Class FileBasedSparseFloatDistanceFunction

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.FileBasedSparseFloatDistanceFunction

All Implemented Interfaces:

DBIDDistanceFunction, DBIDRangeDistanceFunction, DistanceFunction<DBID>

@Alias(value="de.lmu.ifi.dbs.elki.distance.distancefunction.external.FileBasedFloatDistanceFunction")
public class FileBasedSparseFloatDistanceFunction
extends AbstractDBIDRangeDistanceFunction

Distance function that is based on float 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 float[] instead of the hash map?

Since:

0.1

Author:

Elke Achtert, Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileBasedSparseFloatDistanceFunction.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 it.unimi.dsi.fastutil.longs.Long2FloatOpenHashMap	cache The distance cache
protected float	defaultDistance Distance to return when not defined otherwise.
private static Logging	LOG Class logger.
private java.io.File	matrixfile Input file of distance matrix
private int	max Minimum and maximum IDs seen.
private int	min Minimum and maximum IDs seen.
private DistanceParser	parser Distance parser

Constructor Summary

Constructors

Constructor and Description
FileBasedSparseFloatDistanceFunction(DistanceParser parser, java.io.File matrixfile, float defaultDistance) Constructor.

Method Summary

Modifier and Type	Method and Description
void	checkRange(DBIDRange range) Validate the range of DBIDs to use.
double	distance(int i1, int i2) Compute the distance for two integer offsets.
boolean	equals(java.lang.Object obj)
<O extends DBID> DistanceQuery<O>	instantiate(Relation<O> relation) Instantiate with a database to get the actual distance query.
protected void	loadCache(int size, java.io.InputStream in) Fill cache from an input stream.
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, isSquared, isSymmetric

Field Detail

LOG

private static final Logging LOG

Class logger.

cache

private it.unimi.dsi.fastutil.longs.Long2FloatOpenHashMap cache

The distance cache

parser

private DistanceParser parser

Distance parser

matrixfile

private java.io.File matrixfile

Input file of distance matrix

min

private int min

Minimum and maximum IDs seen.

max

private int max

Minimum and maximum IDs seen.

defaultDistance

protected float defaultDistance

Distance to return when not defined otherwise.

Constructor Detail

FileBasedSparseFloatDistanceFunction

public FileBasedSparseFloatDistanceFunction(DistanceParser parser,
                                            java.io.File matrixfile,
                                            float defaultDistance)

Constructor.

Parameters:

parser - Parser

matrixfile - input file

defaultDistance - Default distance (when undefined)

Method Detail

instantiate

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

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:

relation - 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

protected void loadCache(int size,
                         java.io.InputStream in)
                  throws java.io.IOException

Fill cache from an input stream.

Parameters:

size - Expected size

in - Input stream

Throws:

java.io.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

checkRange

public void checkRange(DBIDRange range)

Description copied from interface: DBIDRangeDistanceFunction

Validate the range of DBIDs to use. This will log a warning if an obvious mismatch was found.

Parameters:

range - DBID range

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object