ivory.lsh.data

Class NBitSignature

java.lang.Object

ivory.lsh.data.Signature

ivory.lsh.data.NBitSignature

All Implemented Interfaces:

Comparable, Writable, WritableComparable

public class NBitSignature
extends Signature

A space and time-efficient implementation of Signature. This class is basically a WritableComparable wrapper around the Bits class with many functionalities such as computing hamming distance very efficiently (using bitwise operations).

Author:

ferhanture

Constructor Summary

Constructors

Constructor and Description
NBitSignature()
NBitSignature(Bits b)
NBitSignature(byte[] bits, int len)
NBitSignature(int size) Create a BitsSignature object with the specified number of bits, all initially set to 0.
NBitSignature(NBitSignature other)

Method Summary

Methods

Modifier and Type	Method and Description
void	and(NBitSignature other)
NBitSignature	append(Signature signature)
int	compareTo(NBitSignature other)
int	compareTo(Object obj)
float	cosine(NBitSignature s2)
int	countSetBits()
static int	countSetBits2(int n)
boolean	equals(Object o)
boolean	get(int i)
int	getLongestPrefix(Signature s)
NBitSignature	getSubSignature(int start, int end)
NBitSignature	getSubSignature(int start, int end, Signature subSign)
int	hammingDistance(Signature s)
int	hammingDistance(Signature signature, int threshold)
int	hashCode()
void	or(NBitSignature other)
Signature	perm(ArrayListOfIntsWritable permutation)
void	perm(ArrayListOfIntsWritable permutation, Signature newSign)
void	readFields(DataInput in)
void	set(int i, boolean sign)
int	size()
String	toString()
void	write(DataOutput out)

Methods inherited from class ivory.lsh.data.Signature

createSignature

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

NBitSignature

public NBitSignature()

NBitSignature

public NBitSignature(Bits b)

NBitSignature

public NBitSignature(byte[] bits,
             int len)

NBitSignature

public NBitSignature(int size)

Create a BitsSignature object with the specified number of bits, all initially set to 0.

Parameters:

size - number of bits

NBitSignature

public NBitSignature(NBitSignature other)

Method Detail

and

public void and(NBitSignature other)

append

public NBitSignature append(Signature signature)

compareTo

public int compareTo(NBitSignature other)

compareTo

public int compareTo(Object obj)

cosine

public float cosine(NBitSignature s2)

countSetBits

public int countSetBits()

countSetBits2

public static int countSetBits2(int n)

equals

public boolean equals(Object o)

Overrides:

equals in class Object

get

public boolean get(int i)

getLongestPrefix

public int getLongestPrefix(Signature s)

Overrides:

getLongestPrefix in class Signature

getSubSignature

public NBitSignature getSubSignature(int start,
                            int end)

Specified by:

getSubSignature in class Signature

Parameters:

start - first index to be included in sub-signature

end - last index to be included in sub-signature

Returns:

return a new BitsSignature object, containing the bits of this object from start to end

getSubSignature

public NBitSignature getSubSignature(int start,
                            int end,
                            Signature subSign)

Specified by:

getSubSignature in class Signature

hammingDistance

public int hammingDistance(Signature s)

Specified by:

hammingDistance in class Signature

Returns:

compute hamming distance between this object and signature.

hammingDistance

public int hammingDistance(Signature signature,
                  int threshold)

Specified by:

hammingDistance in class Signature

Returns:

compute hamming distance between this object and signature. early terminate if distance exceeds threshold.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

or

public void or(NBitSignature other)

perm

public Signature perm(ArrayListOfIntsWritable permutation)

Specified by:

perm in class Signature

Returns:

permute this object w.r.t permutation object and return permuted signature

perm

public void perm(ArrayListOfIntsWritable permutation,
        Signature newSign)

Specified by:

perm in class Signature

Parameters:

permutation - permute this object w.r.t permutation object and save permuted signature in permSign

readFields

public void readFields(DataInput in)
                throws IOException

Throws:

IOException

set

public void set(int i,
       boolean sign)

size

public int size()

Specified by:

size in class Signature

toString

public String toString()

Specified by:

toString in class Signature

write

public void write(DataOutput out)
           throws IOException

Throws:

IOException