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/data/users/matthijs/github_faiss/faiss/IndexIVF.h
/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the CC-by-NC license found in the
* LICENSE file in the root directory of this source tree.
*/
// Copyright 2004-present Facebook. All Rights Reserved.
// -*- c++ -*-
#ifndef FAISS_INDEX_IVF_H
#define FAISS_INDEX_IVF_H
#include <vector>
#include "Index.h"
#include "Clustering.h"
#include "Heap.h"
namespace faiss {
/** Index based on a inverted file (IVF)
*
* In the inverted file, the quantizer (an Index instance) provides a
* quantization index for each vector to be added. The quantization
* index maps to a list (aka inverted list or posting list), where the
* id of the vector is then stored.
*
* At search time, the vector to be searched is also quantized, and
* only the list corresponding to the quantization index is
* searched. This speeds up the search by making it
* non-exhaustive. This can be relaxed using multi-probe search: a few
* (nprobe) quantization indices are selected and several inverted
* lists are visited.
*
* Sub-classes implement a post-filtering of the index that refines
* the distance estimation from the query to databse vectors.
*/
struct IndexIVF: Index {
size_t nlist; ///< number of possible key values
size_t nprobe; ///< number of probes at query time
Index * quantizer; ///< quantizer that maps vectors to inverted lists
bool quantizer_trains_alone; ///< just pass over the trainset to quantizer
bool own_fields; ///< whether object owns the quantizer
ClusteringParameters cp; ///< to override default clustering params
std::vector < std::vector<long> > ids; ///< Inverted lists for indexes
/// map for direct access to the elements. Enables reconstruct().
bool maintain_direct_map;
std::vector <long> direct_map;
/** The Inverted file takes a quantizer (an Index) on input,
* which implements the function mapping a vector to a list
* identifier. The pointer is borrowed: the quantizer should not
* be deleted while the IndexIVF is in use.
*/
IndexIVF (Index * quantizer, size_t d, size_t nlist,
MetricType metric = METRIC_INNER_PRODUCT);
void reset() override;
/// Trains the quantizer and calls train_residual to train sub-quantizers
void train(idx_t n, const float* x) override;
/// Quantizes x and calls add_with_key
void add(idx_t n, const float* x) override;
/// Sub-classes that encode the residuals can train their encoders here
/// does nothing by default
virtual void train_residual (idx_t n, const float *x);
/** moves the entries from another dataset to self. On output,
* other is empty. add_id is added to all moved ids (for
* sequential ids, this would be this->ntotal */
virtual void merge_from (IndexIVF &other, idx_t add_id);
/** implemented by sub-classes */
virtual void merge_from_residuals (IndexIVF &other) = 0;
~IndexIVF() override;
size_t get_list_size (size_t list_no) const
{ return ids[list_no].size(); }
/** intialize a direct map
*
* @param new_maintain_direct_map if true, create a direct map,
* else clear it
*/
void make_direct_map (bool new_maintain_direct_map=true);
/// 1= perfectly balanced, >1: imbalanced
double imbalance_factor () const;
/// display some stats about the inverted lists
void print_stats () const;
IndexIVF ();
};
struct IndexIVFFlatStats {
size_t nq; // nb of queries run
size_t nlist; // nb of inverted lists scanned
size_t ndis; // nb of distancs computed
size_t npartial; // nb of bound computations (IndexIVFFlatIPBounds)
IndexIVFFlatStats () {reset (); }
void reset ();
};
// global var that collects them all
extern IndexIVFFlatStats indexIVFFlat_stats;
/** Inverted file with stored vectors. Here the inverted file
* pre-selects the vectors to be searched, but they are not otherwise
* encoded.
*/
struct IndexIVFFlat: IndexIVF {
/** Inverted list of original vectors. Each list is a nl * d
* matrix, where nl is the nb of vectors stored in the list. */
std::vector < std::vector<float> > vecs;
IndexIVFFlat (
Index * quantizer, size_t d, size_t nlist_,
MetricType = METRIC_INNER_PRODUCT);
/// same as add_with_ids, with precomputed coarse quantizer
virtual void add_core (idx_t n, const float * x, const long *xids,
const long *precomputed_idx);
/// implemented for all IndexIVF* classes
void add_with_ids(idx_t n, const float* x, const long* xids) override;
void search(
idx_t n,
const float* x,
idx_t k,
float* distances,
idx_t* labels) const override;
/// perform search, without computing the assignment to the quantizer
void search_preassigned (idx_t n, const float *x, idx_t k,
const idx_t *assign,
float *distances, idx_t *labels) const;
void range_search(
idx_t n,
const float* x,
float radius,
RangeSearchResult* result) const override;
/** copy a subset of the entries index to the other index
*
* if subset_type == 0: copies ids in [a1, a2)
* if subset_type == 1: copies ids if id % a1 == a2
*/
void copy_subset_to (IndexIVFFlat & other, int subset_type,
long a1, long a2) const;
void reset() override;
long remove_ids(const IDSelector& sel) override;
/// Implementation of the search for the inner product metric
void search_knn_inner_product (
size_t nx, const float * x,
const long * keys,
float_minheap_array_t * res) const;
/// Implementation of the search for the L2 metric
void search_knn_L2sqr (
size_t nx, const float * x,
const long * keys,
float_maxheap_array_t * res) const;
/** Update a subset of vectors.
*
* The index must have a direct_map
*
* @param nv nb of vectors to update
* @param idx vector indices to update, size nv
* @param v vectors of new values, size nv*d
*/
void update_vectors (int nv, idx_t *idx, const float *v);
void reconstruct(idx_t key, float* recons) const override;
void merge_from_residuals(IndexIVF& other) override;
IndexIVFFlat () {}
};
struct IndexIVFFlatIPBounds: IndexIVFFlat {
/// nb of dimensions of pre-filter
size_t fsize;
/// norm of remainder (dimensions fsize:d)
std::vector<std::vector<float> > part_norms;
IndexIVFFlatIPBounds (
Index * quantizer, size_t d, size_t nlist,
size_t fsize);
void add_core(
idx_t n,
const float* x,
const long* xids,
const long* precomputed_idx) override;
void search(
idx_t n,
const float* x,
idx_t k,
float* distances,
idx_t* labels) const override;
};
} // namespace faiss
#endif
faiss::IndexIVF
Definition: IndexIVF.h:45
faiss::IndexIVFFlat::search_preassigned
void search_preassigned(idx_t n, const float *x, idx_t k, const idx_t *assign, float *distances, idx_t *labels) const
perform search, without computing the assignment to the quantizer
Definition: IndexIVF.cpp:383
faiss::IndexIVFFlat::search_knn_L2sqr
void search_knn_L2sqr(size_t nx, const float *x, const long *keys, float_maxheap_array_t *res) const
Implementation of the search for the L2 metric.
Definition: IndexIVF.cpp:323
faiss::IndexIVF::imbalance_factor
double imbalance_factor() const
1= perfectly balanced, &gt;1: imbalanced
Definition: IndexIVF.cpp:140
faiss::IndexIVF::nprobe
size_t nprobe
number of probes at query time
Definition: IndexIVF.h:47
faiss::IndexIVFFlat::reconstruct
void reconstruct(idx_t key, float *recons) const override
Definition: IndexIVF.cpp:573
faiss::Index::assign
void assign(idx_t n, const float *x, idx_t *labels, idx_t k=1)
Definition: Index.cpp:23
faiss::IDSelector
Definition: AuxIndexStructures.h:52
faiss::IndexIVF::quantizer_trains_alone
bool quantizer_trains_alone
just pass over the trainset to quantizer
Definition: IndexIVF.h:50
faiss::IndexIVFFlat::range_search
void range_search(idx_t n, const float *x, float radius, RangeSearchResult *result) const override
Definition: IndexIVF.cpp:401
faiss::IndexIVFFlat::copy_subset_to
void copy_subset_to(IndexIVFFlat &other, int subset_type, long a1, long a2) const
Definition: IndexIVF.cpp:463
faiss::IndexIVFFlat::merge_from_residuals
void merge_from_residuals(IndexIVF &other) override
Definition: IndexIVF.cpp:451
faiss::IndexIVF::train_residual
virtual void train_residual(idx_t n, const float *x)
Definition: IndexIVF.cpp:131
faiss::IndexIVFFlat::remove_ids
long remove_ids(const IDSelector &sel) override
Definition: IndexIVF.cpp:541
faiss::IndexIVFFlat
Definition: IndexIVF.h:132
faiss::IndexIVF::ids
std::vector< std::vector< long > > ids
Inverted lists for indexes.
Definition: IndexIVF.h:55
faiss::IndexIVFFlatStats
Definition: IndexIVF.h:111
faiss::Index::d
int d
vector dimension
Definition: Index.h:64
faiss::IndexIVF::quantizer
Index * quantizer
quantizer that maps vectors to inverted lists
Definition: IndexIVF.h:49
faiss::IndexIVF::train
void train(idx_t n, const float *x) override
Trains the quantizer and calls train_residual to train sub-quantizers.
Definition: IndexIVF.cpp:102
faiss::IndexIVF::cp
ClusteringParameters cp
to override default clustering params
Definition: IndexIVF.h:53
faiss::IndexIVFFlat::add_with_ids
void add_with_ids(idx_t n, const float *x, const long *xids) override
implemented for all IndexIVF* classes
Definition: IndexIVF.cpp:216
faiss::IndexIVF::own_fields
bool own_fields
whether object owns the quantizer
Definition: IndexIVF.h:51
faiss::HeapArray
Definition: Heap.h:350
faiss::Index::idx_t
long idx_t
all indices are this type
Definition: Index.h:62
faiss::IndexIVFFlat::reset
void reset() override
removes all elements from the database.
Definition: IndexIVF.cpp:533
faiss::IndexIVF::reset
void reset() override
removes all elements from the database.
Definition: IndexIVF.cpp:93
faiss::IndexIVFFlat::update_vectors
void update_vectors(int nv, idx_t *idx, const float *v)
Definition: IndexIVF.cpp:488
faiss::IndexIVFFlatIPBounds::search
void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
Definition: IndexIVF.cpp:694
faiss::IndexIVFFlatIPBounds::part_norms
std::vector< std::vector< float > > part_norms
norm of remainder (dimensions fsize:d)
Definition: IndexIVF.h:213
faiss::IndexIVFFlatIPBounds
Definition: IndexIVF.h:207
faiss::IndexIVFFlatIPBounds::fsize
size_t fsize
nb of dimensions of pre-filter
Definition: IndexIVF.h:210
faiss::RangeSearchResult
Definition: AuxIndexStructures.h:29
faiss::IndexIVF::merge_from_residuals
virtual void merge_from_residuals(IndexIVF &other)=0
faiss::IndexIVF::make_direct_map
void make_direct_map(bool new_maintain_direct_map=true)
Definition: IndexIVF.cpp:68
faiss::ClusteringParameters
Definition: Clustering.h:24
faiss::IndexIVF::print_stats
void print_stats() const
display some stats about the inverted lists
Definition: IndexIVF.cpp:149
faiss::IndexIVFFlatIPBounds::add_core
void add_core(idx_t n, const float *x, const long *xids, const long *precomputed_idx) override
same as add_with_ids, with precomputed coarse quantizer
Definition: IndexIVF.cpp:599
faiss::IndexIVF::nlist
size_t nlist
number of possible key values
Definition: IndexIVF.h:46
faiss::Index
Definition: Index.h:60
faiss::IndexIVF::add
void add(idx_t n, const float *x) override
Quantizes x and calls add_with_key.
Definition: IndexIVF.cpp:63
faiss::IndexIVFFlat::search_knn_inner_product
void search_knn_inner_product(size_t nx, const float *x, const long *keys, float_minheap_array_t *res) const
Implementation of the search for the inner product metric.
Definition: IndexIVF.cpp:272
faiss::IndexIVF::maintain_direct_map
bool maintain_direct_map
map for direct access to the elements. Enables reconstruct().
Definition: IndexIVF.h:58
faiss::IndexIVF::merge_from
virtual void merge_from(IndexIVF &other, idx_t add_id)
Definition: IndexIVF.cpp:169
faiss::MetricType
MetricType
Some algorithms support both an inner product vetsion and a L2 search version.
Definition: Index.h:43
faiss::IndexIVFFlat::vecs
std::vector< std::vector< float > > vecs
Definition: IndexIVF.h:135
faiss::IndexIVFFlat::add_core
virtual void add_core(idx_t n, const float *x, const long *xids, const long *precomputed_idx)
same as add_with_ids, with precomputed coarse quantizer
Definition: IndexIVF.cpp:221
faiss::IndexIVFFlat::search
void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
Definition: IndexIVF.cpp:373