rtflann::lsh::LshTable< ElementType > Class Template Reference

#include <lsh_table.h>

Public Types
typedef std::map< BucketKey, Bucket >	BucketsSpace
typedef std::vector< Bucket >	BucketsSpeed

Public Member Functions
void	add (unsigned int value, const ElementType *feature)
void	add (const std::vector< std::pair< size_t, ElementType *> > &features)
const Bucket *	getBucketFromKey (BucketKey key) const
size_t	getKey (const ElementType *) const
template<>
size_t	getKey (const unsigned char *feature) const
LshStats	getStats () const
template<>
LshStats	getStats () const
	LshTable ()
	LshTable (unsigned int, unsigned int)
template<>
	LshTable (unsigned int feature_size, unsigned int subsignature_size)

Private Types
enum	SpeedLevel { kArray, kBitsetHash, kHash }

Private Member Functions
void	initialize (size_t key_size)
void	optimize ()
template<typename Archive >
void	serialize (Archive &ar)

Private Attributes
BucketsSpace	buckets_space_
BucketsSpeed	buckets_speed_
DynamicBitset	key_bitset_
unsigned int	key_size_
std::vector< size_t >	mask_
SpeedLevel	speed_level_

Friends
struct	serialization::access

Detailed Description

template<typename ElementType>
class rtflann::lsh::LshTable< ElementType >

Lsh hash table. As its key is a sub-feature, and as usually the size of it is pretty small, we keep it as a continuous memory array. The value is an index in the corpus of features (we keep it as an unsigned int for pure memory reasons, it could be a size_t)

Definition at line 125 of file lsh_table.h.

Member Typedef Documentation

BucketsSpace

template<typename ElementType>

typedef std::map<BucketKey, Bucket> rtflann::lsh::LshTable< ElementType >::BucketsSpace

A container of all the feature indices. Optimized for space

Definition at line 133 of file lsh_table.h.

BucketsSpeed

template<typename ElementType>

typedef std::vector<Bucket> rtflann::lsh::LshTable< ElementType >::BucketsSpeed

A container of all the feature indices. Optimized for speed

Definition at line 138 of file lsh_table.h.

Member Enumeration Documentation

SpeedLevel

template<typename ElementType>

enum rtflann::lsh::LshTable::SpeedLevel

private

defines the speed fo the implementation kArray uses a vector for storing data kBitsetHash uses a hash map but checks for the validity of a key with a bitset kHash uses a hash map only

Enumerator
kArray
kBitsetHash
kHash

Definition at line 252 of file lsh_table.h.

Constructor & Destructor Documentation

LshTable() [1/3]

template<typename ElementType>

rtflann::lsh::LshTable< ElementType >::LshTable ( )

inline

Default constructor

Definition at line 142 of file lsh_table.h.

LshTable() [2/3]

template<typename ElementType>

rtflann::lsh::LshTable< ElementType >::LshTable ( unsigned  int, unsigned  int  )

inline

Default constructor Create the mask and allocate the memory

Parameters

feature_size	is the size of the feature (considered as a ElementType[])
key_size	is the number of bits that are turned on in the feature

Definition at line 151 of file lsh_table.h.

LshTable() [3/3]

template<>

rtflann::lsh::LshTable< unsigned char >::LshTable ( unsigned int  feature_size, unsigned int  subsignature_size  )

inline

Definition at line 358 of file lsh_table.h.

Member Function Documentation

add() [1/2]

template<typename ElementType>

void rtflann::lsh::LshTable< ElementType >::add ( unsigned int  value, const ElementType *  feature  )

inline

Add a feature to the table

Parameters

value	the value to store for that feature
feature	the feature itself

Definition at line 161 of file lsh_table.h.

add() [2/2]

template<typename ElementType>

void rtflann::lsh::LshTable< ElementType >::add ( const std::vector< std::pair< size_t, ElementType *> > &  features )

inline

Add a set of features to the table

Parameters

dataset

the values to store

Definition at line 188 of file lsh_table.h.

getBucketFromKey()

template<typename ElementType>

const Bucket* rtflann::lsh::LshTable< ElementType >::getBucketFromKey ( BucketKey  key ) const

inline

Get a bucket given the key

Parameters

key

Returns

Definition at line 205 of file lsh_table.h.

getKey() [1/2]

template<typename ElementType>

size_t rtflann::lsh::LshTable< ElementType >::getKey ( const ElementType *  ) const

inline

Compute the sub-signature of a feature

Definition at line 234 of file lsh_table.h.

getKey() [2/2]

template<>

size_t rtflann::lsh::LshTable< unsigned char >::getKey ( const unsigned char *  feature ) const

inline

Return the Subsignature of a feature

Parameters

feature

the feature to analyze

Definition at line 399 of file lsh_table.h.

getStats() [1/2]

template<typename ElementType>

LshStats rtflann::lsh::LshTable< ElementType >::getStats

(

)

const

Get statistics about the table

Returns

getStats() [2/2]

template<>

LshStats rtflann::lsh::LshTable< unsigned char >::getStats ( ) const

inline

Definition at line 432 of file lsh_table.h.

initialize()

template<typename ElementType>

void rtflann::lsh::LshTable< ElementType >::initialize ( size_t  key_size )

inlineprivate

Initialize some variables

Definition at line 259 of file lsh_table.h.

optimize()

template<typename ElementType>

void rtflann::lsh::LshTable< ElementType >::optimize ( )

inlineprivate

Optimize the table for speed/space

Definition at line 267 of file lsh_table.h.

serialize()

template<typename ElementType>

template<typename Archive >

void rtflann::lsh::LshTable< ElementType >::serialize ( Archive &  ar )

inlineprivate

Definition at line 301 of file lsh_table.h.

Friends And Related Function Documentation

serialization::access

template<typename ElementType>

friend struct serialization::access

friend

Definition at line 325 of file lsh_table.h.

Member Data Documentation

buckets_space_

template<typename ElementType>

BucketsSpace rtflann::lsh::LshTable< ElementType >::buckets_space_

private

The hash table of all the buckets in case we cannot use the speed version

Definition at line 333 of file lsh_table.h.

buckets_speed_

template<typename ElementType>

BucketsSpeed rtflann::lsh::LshTable< ElementType >::buckets_speed_

private

The vector of all the buckets if they are held for speed

Definition at line 329 of file lsh_table.h.

key_bitset_

template<typename ElementType>

DynamicBitset rtflann::lsh::LshTable< ElementType >::key_bitset_

private

If the subkey is small enough, it will keep track of which subkeys are set through that bitset That is just a speedup so that we don't look in the hash table (which can be mush slower that checking a bitset)

Definition at line 341 of file lsh_table.h.

key_size_

template<typename ElementType>

unsigned int rtflann::lsh::LshTable< ElementType >::key_size_

private

The size of the sub-signature in bits

Definition at line 345 of file lsh_table.h.

mask_

template<typename ElementType>

std::vector<size_t> rtflann::lsh::LshTable< ElementType >::mask_

private

The mask to apply to a feature to get the hash key Only used in the unsigned char case

Definition at line 351 of file lsh_table.h.

speed_level_

template<typename ElementType>

SpeedLevel rtflann::lsh::LshTable< ElementType >::speed_level_

private

What is used to store the data

Definition at line 336 of file lsh_table.h.

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The documentation for this class was generated from the following file:

• lsh_table.h