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test_pairs_decoding.cpp
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 #include <cstdio>
10 #include <cstdlib>
11
12 #include <memory>
13 #include <vector>
14
15 #include <gtest/gtest.h>
16
17 #include <faiss/IndexIVF.h>
18 #include <faiss/AutoTune.h>
19 #include <faiss/VectorTransform.h>
20
21
22 /*************************************************************
23 * The functions to test, that can be useful in FANN
24 *************************************************************/
25
26 /* Returns the cluster the embeddings belong to.
27 *
28 * @param index Index, which should be an IVF index
29 * (otherwise there are no clusters)
30 * @param embeddings object descriptors for which the centroids should be found,
31 * size num_objects * d
32 * @param cebtroid_ids
33 * cluster id each object belongs to, size num_objects
34 */
35 void Search_centroid(faiss::Index *index,
36 const float* embeddings, int num_objects,
37 int64_t* centroid_ids)
38 {
39 const float *x = embeddings;
40 std::unique_ptr<float> del;
41 if (auto index_pre = dynamic_cast<faiss::IndexPreTransform*>(index)) {
42 x = index_pre->apply_chain(num_objects, x);
43 del.reset((float*)x);
44 index = index_pre->index;
45 }
46 faiss::IndexIVF* index_ivf = dynamic_cast<faiss::IndexIVF*>(index);
47 assert(index_ivf);
48 index_ivf->quantizer->assign(num_objects, x, centroid_ids);
49 }
50
51
52
53 /* Returns the cluster the embeddings belong to.
54 *
55 * @param index Index, which should be an IVF index
56 * (otherwise there are no clusters)
57 * @param query_centroid_ids
58 * centroid ids corresponding to the query vectors (size n)
59 * @param result_centroid_ids
60 * centroid ids corresponding to the results (size n * k)
61 * other arguments are the same as the standard search function
62 */
63 void search_and_retrun_centroids(faiss::Index *index,
64 size_t n,
65 const float* xin,
66 long k,
67 float *distances,
68 int64_t* labels,
69 int64_t* query_centroid_ids,
70 int64_t* result_centroid_ids)
71 {
72 const float *x = xin;
73 std::unique_ptr<float> del;
74 if (auto index_pre = dynamic_cast<faiss::IndexPreTransform*>(index)) {
75 x = index_pre->apply_chain(n, x);
76 del.reset((float*)x);
77 index = index_pre->index;
78 }
79 faiss::IndexIVF* index_ivf = dynamic_cast<faiss::IndexIVF*>(index);
80 assert(index_ivf);
81
82 size_t nprobe = index_ivf->nprobe;
83 std::vector<long> cent_nos (n * nprobe);
84 std::vector<float> cent_dis (n * nprobe);
85 index_ivf->quantizer->search(
86 n, x, nprobe, cent_dis.data(), cent_nos.data());
87
88 if (query_centroid_ids) {
89 for (size_t i = 0; i < n; i++)
90 query_centroid_ids[i] = cent_nos[i * nprobe];
91 }
92
93 index_ivf->search_preassigned (n, x, k,
94 cent_nos.data(), cent_dis.data(),
95 distances, labels, true);
96
97 for (size_t i = 0; i < n * k; i++) {
98 int64_t label = labels[i];
99 if (label < 0) {
100 if (result_centroid_ids)
101 result_centroid_ids[i] = -1;
102 } else {
103 long list_no = label >> 32;
104 long list_index = label & 0xffffffff;
105 if (result_centroid_ids)
106 result_centroid_ids[i] = list_no;
107 labels[i] = index_ivf->ids[list_no][list_index];
108 }
109 }
110 }
111
112 /*************************************************************
113 * Test utils
114 *************************************************************/
115
116 // return an IndexIVF that may be embedded in an IndexPreTransform
117 faiss::IndexIVF * get_IndexIVF(faiss::Index *index) {
118 if (auto index_pre = dynamic_cast<faiss::IndexPreTransform*>(index)) {
119 index = index_pre->index;
120 }
121 faiss::IndexIVF* index_ivf = dynamic_cast<faiss::IndexIVF*>(index);
122 bool t = index_ivf != nullptr;
123 assert(index_ivf);
124 return index_ivf;
125 }
126
127
128
129 // dimension of the vectors to index
130 int d = 64;
131
132 // size of the database we plan to index
133 size_t nb = 8000;
134
135 // nb of queries
136 size_t nq = 200;
137
138 std::vector<float> make_data(size_t n)
139 {
140 std::vector <float> database (n * d);
141 for (size_t i = 0; i < n * d; i++) {
142 database[i] = drand48();
143 }
144 return database;
145 }
146
147 std::unique_ptr<faiss::Index> make_index(const char *index_type,
148 const std::vector<float> & x) {
149
150 auto index = std::unique_ptr<faiss::Index> (
151 faiss::index_factory(d, index_type));
152 index->train(nb, x.data());
153 index->add(nb, x.data());
154 return index;
155 }
156
157 /*************************************************************
158 * Test functions for a given index type
159 *************************************************************/
160
161 bool test_Search_centroid(const char *index_key) {
162 std::vector<float> xb = make_data(nb); // database vectors
163 auto index = make_index(index_key, xb);
164
165 /* First test: find the centroids associated to the database
166 vectors and make sure that each vector does indeed appear in
167 the inverted list corresponding to its centroid */
168
169 std::vector<int64_t> centroid_ids (nb);
170 Search_centroid(index.get(), xb.data(), nb, centroid_ids.data());
171
172 const faiss::IndexIVF * ivf = get_IndexIVF(index.get());
173
174 for(int i = 0; i < nb; i++) {
175 bool found = false;
176 int list_no = centroid_ids[i];
177 for(int j: ivf->ids[list_no]) {
178 if (j == i) {
179 found = true;
180 break;
181 }
182 }
183 if(!found) return false;
184 }
185 return true;
186 }
187
188 int test_search_and_return_centroids(const char *index_key) {
189 std::vector<float> xb = make_data(nb); // database vectors
190 auto index = make_index(index_key, xb);
191
192 std::vector<int64_t> centroid_ids (nb);
193 Search_centroid(index.get(), xb.data(), nb, centroid_ids.data());
194
195 faiss::IndexIVF * ivf = get_IndexIVF(index.get());
196 ivf->nprobe = 4;
197
198 std::vector<float> xq = make_data(nq); // database vectors
199
200 int k = 5;
201
202 // compute a reference search result
203
204 std::vector<long> refI (nq * k);
205 std::vector<float> refD (nq * k);
206 index->search (nq, xq.data(), k, refD.data(), refI.data());
207
208 // compute search result
209
210 std::vector<long> newI (nq * k);
211 std::vector<float> newD (nq * k);
212
213 std::vector<int64_t> query_centroid_ids (nq);
214 std::vector<int64_t> result_centroid_ids (nq * k);
215
216 search_and_retrun_centroids(index.get(),
217 nq, xq.data(), k,
218 newD.data(), newI.data(),
219 query_centroid_ids.data(),
220 result_centroid_ids.data());
221
222 // first verify that we have the same result as the standard search
223
224 if (newI != refI) {
225 return 1;
226 }
227
228 // then check if the result ids are indeed in the inverted list
229 // they are supposed to be in
230
231 for(int i = 0; i < nq * k; i++) {
232 int list_no = result_centroid_ids[i];
233 int result_no = newI[i];
234
235 if (result_no < 0) continue;
236
237 bool found = false;
238
239 for(int j: ivf->ids[list_no]) {
240 if (j == result_no) {
241 found = true;
242 break;
243 }
244 }
245 if(!found) return 2;
246 }
247 return 0;
248 }
249
250 /*************************************************************
251 * Test entry points
252 *************************************************************/
253
254 TEST(test_Search_centroid, IVFFlat) {
255 bool ok = test_Search_centroid("IVF32,Flat");
256 EXPECT_TRUE(ok);
257 }
258
259 TEST(test_Search_centroid, PCAIVFFlat) {
260 bool ok = test_Search_centroid("PCA16,IVF32,Flat");
261 EXPECT_TRUE(ok);
262 }
263
264 TEST(test_search_and_return_centroids, IVFFlat) {
265 int err = test_search_and_return_centroids("IVF32,Flat");
266 EXPECT_NE(err, 1);
267 EXPECT_NE(err, 2);
268 }
269
270 TEST(test_search_and_return_centroids, PCAIVFFlat) {
271 int err = test_search_and_return_centroids("PCA16,IVF32,Flat");
272 EXPECT_NE(err, 1);
273 EXPECT_NE(err, 2);
274 }
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::nprobe
size_t nprobe
number of probes at query time
Definition: IndexIVF.h:47
faiss::Index::train
virtual void train(idx_t, const float *)
Definition: Index.h:89
faiss::Index::assign
void assign(idx_t n, const float *x, idx_t *labels, idx_t k=1)
Definition: Index.cpp:23
faiss::IndexIVF::ids
std::vector< std::vector< long > > ids
Inverted lists for indexes.
Definition: IndexIVF.h:62
faiss::IndexIVF::quantizer
Index * quantizer
quantizer that maps vectors to inverted lists
Definition: IndexIVF.h:49
faiss::Index::add
virtual void add(idx_t n, const float *x)=0
faiss::Index::search
virtual void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const =0
faiss::Index
Definition: Index.h:60
faiss::index_factory
Index * index_factory(int d, const char *description_in, MetricType metric)
Definition: AutoTune.cpp:668