org.openimaj.lsh.functions

Class DoubleHyperplaneL1Factory

java.lang.Object

org.openimaj.lsh.functions.RandomisedHashFunctionFactory<double[]>

org.openimaj.lsh.functions.DoubleHashFunctionFactory

org.openimaj.lsh.functions.DoubleHyperplaneL1Factory

All Implemented Interfaces:

HashFunctionFactory<double[]>

@Reference(type=Inproceedings,
           author={"Lv, Qin","Charikar, Moses","Li, Kai"},
           title="Image similarity search with compact data structures",
           year="2004",
           booktitle="Proceedings of the thirteenth ACM international conference on Information and knowledge management",
           pages={"208","","217"},
           url="http://doi.acm.org/10.1145/1031171.1031213",
           publisher="ACM",
           series="CIKM \'04")
public class DoubleHyperplaneL1Factory
extends DoubleHashFunctionFactory

A hash function factory that produces hash functions that approximate L1 (city-block) distance in closed spaces using random axis-aligned hyperplanes.

The hash function hashes the input vector into a binary value (i.e. 0 or 1). It works by choosing a random dimension and a random threshold along that dimension (between a given minimum and maximum which define the closed space). Input vectors whose element at the chosen dimension is greater than or equal to the threshold generate a 1; values less than the threshold generate a 0.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Field Summary

Fields inherited from class org.openimaj.lsh.functions.RandomisedHashFunctionFactory

ndims, rng

Constructor Summary

Constructors

Constructor and Description
DoubleHyperplaneL1Factory(int ndims, cern.jet.random.engine.MersenneTwister rng, double min, double max) Construct with the given arguments.

Method Summary

Modifier and Type	Method and Description
org.openimaj.lsh.functions.DoubleHyperplaneL1Factory.Function	create() Construct a new HashFunction.
protected DoubleFVComparison	fvDistanceFunction()

Methods inherited from class org.openimaj.lsh.functions.DoubleHashFunctionFactory

distanceFunction

Methods inherited from class java.lang.Object

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

Constructor Detail

DoubleHyperplaneL1Factory

public DoubleHyperplaneL1Factory(int ndims,
                                 cern.jet.random.engine.MersenneTwister rng,
                                 double min,
                                 double max)

Construct with the given arguments.

Parameters:

ndims - The number of dimensions

rng - A random number generator

min - The minimum bound of the space

max - The maximum bound of the space

Method Detail

create

public org.openimaj.lsh.functions.DoubleHyperplaneL1Factory.Function create()

Description copied from interface: HashFunctionFactory

Construct a new HashFunction.

Returns:

the new HashFunction

fvDistanceFunction

protected DoubleFVComparison fvDistanceFunction()

Specified by:

fvDistanceFunction in class DoubleHashFunctionFactory