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test_ivfpq_codec.cpp
/**
* 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.
*/
#include <cstdio>
#include <cstdlib>
#include <gtest/gtest.h>
#include <faiss/IndexIVFPQ.h>
#include <faiss/IndexFlat.h>
#include <faiss/utils.h>
// dimension of the vectors to index
int d = 64;
// size of the database we plan to index
size_t nb = 8000;
double eval_codec_error (long ncentroids, long m, const std::vector<float> &v)
{
faiss::IndexFlatL2 coarse_quantizer (d);
faiss::IndexIVFPQ index (&coarse_quantizer, d,
ncentroids, m, 8);
index.pq.cp.niter = 10; // speed up train
index.train (nb, v.data());
// encode and decode to compute reconstruction error
std::vector<long> keys (nb);
std::vector<uint8_t> codes (nb * m);
index.encode_multiple (nb, keys.data(), v.data(), codes.data(), true);
std::vector<float> v2 (nb * d);
index.decode_multiple (nb, keys.data(), codes.data(), v2.data());
return faiss::fvec_L2sqr (v.data(), v2.data(), nb * d);
}
TEST(IVFPQ, codec) {
std::vector <float> database (nb * d);
for (size_t i = 0; i < nb * d; i++) {
database[i] = drand48();
}
double err0 = eval_codec_error(16, 8, database);
// should be more accurate as there are more coarse centroids
double err1 = eval_codec_error(128, 8, database);
EXPECT_GT(err0, err1);
// should be more accurate as there are more PQ codes
double err2 = eval_codec_error(16, 16, database);
EXPECT_GT(err0, err2);
}
faiss::fvec_L2sqr
float fvec_L2sqr(const float *x, const float *y, size_t d)
Squared L2 distance between two vectors.
Definition: utils.cpp:432
faiss::IndexFlatL2
Definition: IndexFlat.h:81
faiss::IndexIVFPQ
Definition: IndexIVFPQ.h:30