de.lmu.ifi.dbs.elki.index.lsh.hashfunctions

Class CosineLocalitySensitiveHashFunction

java.lang.Object

de.lmu.ifi.dbs.elki.index.lsh.hashfunctions.CosineLocalitySensitiveHashFunction

All Implemented Interfaces:

LocalitySensitiveHashFunction<NumberVector>

@Reference(authors="M.S. Charikar",
           title="Similarity estimation techniques from rounding algorithms",
           booktitle="Proc. 34th ACM Symposium on Theory of computing, STOC\'02",
           url="https://dx.doi.org/10.1145/509907.509965")
public class CosineLocalitySensitiveHashFunction
extends Object
implements LocalitySensitiveHashFunction<NumberVector>

Random projection family to use with sparse vectors. Reference:

M.S. Charikar
Similarity estimation techniques from rounding algorithms
Proc. 34th ACM Symposium on Theory of computing, STOC'02

Author:

Evgeniy Faerman

Field Summary

Fields

Modifier and Type	Field and Description
private RandomProjectionFamily.Projection	projection Projection function.

Constructor Summary

Constructors

Constructor and Description
CosineLocalitySensitiveHashFunction(RandomProjectionFamily.Projection projection) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	getNumberOfProjections() Get the number of projections performed.
int	hashObject(NumberVector obj) Compute the hash value of an object.
int	hashObject(NumberVector obj, double[] buf) Compute the hash value of an object (faster version).

Methods inherited from class java.lang.Object

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

Field Detail

projection

private RandomProjectionFamily.Projection projection

Projection function.

Constructor Detail

CosineLocalitySensitiveHashFunction

public CosineLocalitySensitiveHashFunction(RandomProjectionFamily.Projection projection)

Constructor.

Parameters:

projection - Projection

Method Detail

hashObject

public int hashObject(NumberVector obj)

Description copied from interface: LocalitySensitiveHashFunction

Compute the hash value of an object.

Specified by:

hashObject in interface LocalitySensitiveHashFunction<NumberVector>

Parameters:

obj - Object to hash

Returns:

Hash value

hashObject

public int hashObject(NumberVector obj,
             double[] buf)

Description copied from interface: LocalitySensitiveHashFunction

Compute the hash value of an object (faster version).

Specified by:

hashObject in interface LocalitySensitiveHashFunction<NumberVector>

Parameters:

obj - Object to hash

buf - Buffer, sized according to the number of projections.

Returns:

Hash value

getNumberOfProjections

public int getNumberOfProjections()

Description copied from interface: LocalitySensitiveHashFunction

Get the number of projections performed.

Specified by:

getNumberOfProjections in interface LocalitySensitiveHashFunction<NumberVector>

Returns:

Number of projections.