Faiss

- Main Page
- Namespaces
- Classes
- Files

- File List

All Classes Namespaces Functions Variables Typedefs Enumerations Enumerator Friends
/data/users/matthijs/github_faiss/faiss/IndexIVF.h
1 /**
2 * Copyright (c) 2015-present, Facebook, Inc.
3 * All rights reserved.
4 *
5 * This source code is licensed under the BSD+Patents license found in the
6 * LICENSE file in the root directory of this source tree.
7 */
8
9 // Copyright 2004-present Facebook. All Rights Reserved.
10 // -*- c++ -*-
11
12 #ifndef FAISS_INDEX_IVF_H
13 #define FAISS_INDEX_IVF_H
14
15
16 #include <vector>
17
18
19 #include "Index.h"
20 #include "Clustering.h"
21 #include "Heap.h"
22
23
24 namespace faiss {
25
26
27
28 /** Index based on a inverted file (IVF)
29 *
30 * In the inverted file, the quantizer (an Index instance) provides a
31 * quantization index for each vector to be added. The quantization
32 * index maps to a list (aka inverted list or posting list), where the
33 * id of the vector is then stored.
34 *
35 * At search time, the vector to be searched is also quantized, and
36 * only the list corresponding to the quantization index is
37 * searched. This speeds up the search by making it
38 * non-exhaustive. This can be relaxed using multi-probe search: a few
39 * (nprobe) quantization indices are selected and several inverted
40 * lists are visited.
41 *
42 * Sub-classes implement a post-filtering of the index that refines
43 * the distance estimation from the query to databse vectors.
44 */
45 struct IndexIVF: Index {
46 size_t nlist; ///< number of possible key values
47 size_t nprobe; ///< number of probes at query time
48
49 Index * quantizer; ///< quantizer that maps vectors to inverted lists
50
51 /**
52 * = 0: use the quantizer as index in a kmeans training
53 * = 1: just pass on the training set to the train() of the quantizer
54 * = 2: kmeans training on a flat index + add the centroids to the quantizer
55 */
56 char quantizer_trains_alone;
57 bool own_fields; ///< whether object owns the quantizer
58
59 ClusteringParameters cp; ///< to override default clustering params
60 Index *clustering_index; ///< to override index used during clustering
61
62 std::vector < std::vector<long> > ids; ///< Inverted lists for indexes
63
64 size_t code_size; ///< code size per vector in bytes
65 std::vector < std::vector<uint8_t> > codes; // binary codes, size nlist
66
67 /// map for direct access to the elements. Enables reconstruct().
68 bool maintain_direct_map;
69 std::vector <long> direct_map;
70
71 /** The Inverted file takes a quantizer (an Index) on input,
72 * which implements the function mapping a vector to a list
73 * identifier. The pointer is borrowed: the quantizer should not
74 * be deleted while the IndexIVF is in use.
75 */
76 IndexIVF (Index * quantizer, size_t d, size_t nlist,
77 MetricType metric = METRIC_INNER_PRODUCT);
78
79 void reset() override;
80
81 /// Trains the quantizer and calls train_residual to train sub-quantizers
82 void train(idx_t n, const float* x) override;
83
84 /// Quantizes x and calls add_with_key
85 void add(idx_t n, const float* x) override;
86
87 /// Sub-classes that encode the residuals can train their encoders here
88 /// does nothing by default
89 virtual void train_residual (idx_t n, const float *x);
90
91
92 /** search a set of vectors, that are pre-quantized by the IVF
93 * quantizer. Fill in the corresponding heaps with the query
94 * results. search() calls this.
95 *
96 * @param n nb of vectors to query
97 * @param x query vectors, size nx * d
98 * @param assign coarse quantization indices, size nx * nprobe
99 * @param centroid_dis
100 * distances to coarse centroids, size nx * nprobe
101 * @param distance
102 * output distances, size n * k
103 * @param labels output labels, size n * k
104 * @param store_pairs store inv list index + inv list offset
105 * instead in upper/lower 32 bit of result,
106 * instead of ids (used for reranking).
107 */
108 virtual void search_preassigned (idx_t n, const float *x, idx_t k,
109 const idx_t *assign,
110 const float *centroid_dis,
111 float *distances, idx_t *labels,
112 bool store_pairs) const = 0;
113
114 /** assign the vectors, then call search_preassign */
115 virtual void search (idx_t n, const float *x, idx_t k,
116 float *distances, idx_t *labels) const override;
117
118
119 /// Dataset manipulation functions
120
121 long remove_ids(const IDSelector& sel) override;
122
123 /** moves the entries from another dataset to self. On output,
124 * other is empty. add_id is added to all moved ids (for
125 * sequential ids, this would be this->ntotal */
126 virtual void merge_from (IndexIVF &other, idx_t add_id);
127
128 /** copy a subset of the entries index to the other index
129 *
130 * if subset_type == 0: copies ids in [a1, a2)
131 * if subset_type == 1: copies ids if id % a1 == a2
132 * if subset_type == 2: copies inverted lists such that a1
133 * elements are left before and a2 elements are after
134 */
135 virtual void copy_subset_to (IndexIVF & other, int subset_type,
136 long a1, long a2) const;
137
138 ~IndexIVF() override;
139
140 size_t get_list_size (size_t list_no) const
141 { return ids[list_no].size(); }
142
143 /** intialize a direct map
144 *
145 * @param new_maintain_direct_map if true, create a direct map,
146 * else clear it
147 */
148 void make_direct_map (bool new_maintain_direct_map=true);
149
150 /// 1= perfectly balanced, >1: imbalanced
151 double imbalance_factor () const;
152
153 /// display some stats about the inverted lists
154 void print_stats () const;
155
156 IndexIVF ();
157 };
158
159
160 struct IndexIVFFlatStats {
161 size_t nq; // nb of queries run
162 size_t nlist; // nb of inverted lists scanned
163 size_t ndis; // nb of distancs computed
164 size_t npartial; // nb of bound computations (IndexIVFFlatIPBounds)
165
166 IndexIVFFlatStats () {reset (); }
167 void reset ();
168 };
169
170 // global var that collects them all
171 extern IndexIVFFlatStats indexIVFFlat_stats;
172
173
174
175
176
177 /** Inverted file with stored vectors. Here the inverted file
178 * pre-selects the vectors to be searched, but they are not otherwise
179 * encoded, the code array just contains the raw float entries.
180 */
181 struct IndexIVFFlat: IndexIVF {
182
183 IndexIVFFlat (
184 Index * quantizer, size_t d, size_t nlist_,
185 MetricType = METRIC_INNER_PRODUCT);
186
187 /// same as add_with_ids, with precomputed coarse quantizer
188 virtual void add_core (idx_t n, const float * x, const long *xids,
189 const long *precomputed_idx);
190
191 /// implemented for all IndexIVF* classes
192 void add_with_ids(idx_t n, const float* x, const long* xids) override;
193
194 void search_preassigned (idx_t n, const float *x, idx_t k,
195 const idx_t *assign,
196 const float *centroid_dis,
197 float *distances, idx_t *labels,
198 bool store_pairs) const override;
199
200 void range_search(
201 idx_t n,
202 const float* x,
203 float radius,
204 RangeSearchResult* result) const override;
205
206 /** Update a subset of vectors.
207 *
208 * The index must have a direct_map
209 *
210 * @param nv nb of vectors to update
211 * @param idx vector indices to update, size nv
212 * @param v vectors of new values, size nv*d
213 */
214 void update_vectors (int nv, idx_t *idx, const float *v);
215
216 void reconstruct(idx_t key, float* recons) const override;
217
218 IndexIVFFlat () {}
219 };
220
221
222
223 } // namespace faiss
224
225
226
227
228
229 #endif
faiss::IndexIVF::search_preassigned
virtual void search_preassigned(idx_t n, const float *x, idx_t k, const idx_t *assign, const float *centroid_dis, float *distances, idx_t *labels, bool store_pairs) const =0
faiss::IndexIVF
Definition: IndexIVF.h:45
faiss::IndexIVF::imbalance_factor
double imbalance_factor() const
1= perfectly balanced, &gt;1: imbalanced
Definition: IndexIVF.cpp:216
faiss::IndexIVF::copy_subset_to
virtual void copy_subset_to(IndexIVF &other, int subset_type, long a1, long a2) const
Definition: IndexIVF.cpp:272
faiss::IndexIVF::quantizer_trains_alone
char quantizer_trains_alone
Definition: IndexIVF.h:56
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:646
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::IndexIVFFlat::range_search
void range_search(idx_t n, const float *x, float radius, RangeSearchResult *result) const override
Definition: IndexIVF.cpp:548
faiss::IndexIVF::train_residual
virtual void train_residual(idx_t n, const float *x)
Definition: IndexIVF.cpp:208
faiss::IndexIVFFlat
Definition: IndexIVF.h:181
faiss::IndexIVF::ids
std::vector< std::vector< long > > ids
Inverted lists for indexes.
Definition: IndexIVF.h:62
faiss::IndexIVFFlatStats
Definition: IndexIVF.h:160
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:157
faiss::IndexIVF::cp
ClusteringParameters cp
to override default clustering params
Definition: IndexIVF.h:59
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:361
faiss::IndexIVF::clustering_index
Index * clustering_index
to override index used during clustering
Definition: IndexIVF.h:60
faiss::IndexIVF::own_fields
bool own_fields
whether object owns the quantizer
Definition: IndexIVF.h:57
faiss::Index::idx_t
long idx_t
all indices are this type
Definition: Index.h:62
faiss::IndexIVF::reset
void reset() override
removes all elements from the database.
Definition: IndexIVF.cpp:112
faiss::IndexIVFFlat::update_vectors
void update_vectors(int nv, idx_t *idx, const float *v)
Definition: IndexIVF.cpp:598
faiss::RangeSearchResult
Definition: AuxIndexStructures.h:29
faiss::IndexIVF::make_direct_map
void make_direct_map(bool new_maintain_direct_map=true)
Definition: IndexIVF.cpp:71
faiss::ClusteringParameters
Definition: Clustering.h:24
faiss::IndexIVF::print_stats
void print_stats() const
display some stats about the inverted lists
Definition: IndexIVF.cpp:225
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:66
faiss::IndexIVF::remove_ids
long remove_ids(const IDSelector &sel) override
Dataset manipulation functions.
Definition: IndexIVF.cpp:123
faiss::IndexIVF::maintain_direct_map
bool maintain_direct_map
map for direct access to the elements. Enables reconstruct().
Definition: IndexIVF.h:68
faiss::IndexIVF::search
virtual void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
Definition: IndexIVF.cpp:96
faiss::IndexIVFFlat::search_preassigned
void search_preassigned(idx_t n, const float *x, idx_t k, const idx_t *assign, const float *centroid_dis, float *distances, idx_t *labels, bool store_pairs) const override
Definition: IndexIVF.cpp:529
faiss::IndexIVF::merge_from
virtual void merge_from(IndexIVF &other, idx_t add_id)
Definition: IndexIVF.cpp:245
faiss::IndexIVF::code_size
size_t code_size
code size per vector in bytes
Definition: IndexIVF.h:64
faiss::MetricType
MetricType
Some algorithms support both an inner product version and a L2 search version.
Definition: Index.h:43
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:366