org.apache.mahout.math.neighborhood

Class HashedVector

java.lang.Object

org.apache.mahout.math.DelegatingVector

org.apache.mahout.math.WeightedVector

org.apache.mahout.math.neighborhood.HashedVector

All Implemented Interfaces:

Cloneable, Vector

public class HashedVector
extends WeightedVector

Decorates a weighted vector with a locality sensitive hash. The LSH function implemented is the random hyperplane based hash function. See "Similarity Estimation Techniques from Rounding Algorithms" by Moses S. Charikar, section 3. http://www.cs.princeton.edu/courses/archive/spring04/cos598B/bib/CharikarEstim.pdf

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.mahout.math.Vector

Vector.Element

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	INVALID_INDEX

Fields inherited from class org.apache.mahout.math.DelegatingVector

delegate

Constructor Summary

Constructors

Constructor and Description
HashedVector(Vector vector, long hash, int index)
HashedVector(Vector vector, Matrix projection, int index, long mask)
HashedVector(WeightedVector weightedVector, Matrix projection, long mask)

Method Summary

Modifier and Type	Method and Description
static long	computeHash64(Vector vector, Matrix projection)
boolean	equals(Object o)
long	getHash()
int	hammingDistance(long otherHash)
static HashedVector	hash(WeightedVector v, Matrix projection)
static HashedVector	hash(WeightedVector v, Matrix projection, long mask)
int	hashCode()
String	toString()

Methods inherited from class org.apache.mahout.math.WeightedVector

clone, getIndex, getWeight, like, project, project, setIndex, setWeight

Methods inherited from class org.apache.mahout.math.DelegatingVector

aggregate, aggregate, all, asFormatString, assign, assign, assign, assign, assign, assign, cross, divide, dot, get, getDistanceSquared, getElement, getIteratorAdvanceCost, getLengthSquared, getLookupCost, getNumNondefaultElements, getNumNonZeroElements, getQuick, getVector, incrementQuick, invalidateCachedLength, isAddConstantTime, isDense, isSequentialAccess, like, logNormalize, logNormalize, maxValue, maxValueIndex, mergeUpdates, minus, minValue, minValueIndex, nonZeroes, norm, normalize, normalize, plus, plus, set, setQuick, size, times, times, viewPart, zSum

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

INVALID_INDEX

protected static final int INVALID_INDEX

See Also:

Constant Field Values

Constructor Detail

HashedVector

public HashedVector(Vector vector,
                    long hash,
                    int index)

HashedVector

public HashedVector(Vector vector,
                    Matrix projection,
                    int index,
                    long mask)

HashedVector

public HashedVector(WeightedVector weightedVector,
                    Matrix projection,
                    long mask)

Method Detail

computeHash64

public static long computeHash64(Vector vector,
                                 Matrix projection)

hash

public static HashedVector hash(WeightedVector v,
                                Matrix projection)

hash

public static HashedVector hash(WeightedVector v,
                                Matrix projection,
                                long mask)

hammingDistance

public int hammingDistance(long otherHash)

getHash

public long getHash()

toString

public String toString()

Overrides:

toString in class WeightedVector

equals

public boolean equals(Object o)

Overrides:

equals in class DelegatingVector

hashCode

public int hashCode()

Overrides:

hashCode in class DelegatingVector