65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
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/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the CC-by-NC license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <cstdio>
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#include <cstdlib>
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#include <gtest/gtest.h>
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#include <faiss/IndexIVFPQ.h>
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#include <faiss/IndexFlat.h>
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#include <faiss/utils.h>
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// dimension of the vectors to index
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int d = 64;
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// size of the database we plan to index
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size_t nb = 8000;
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double eval_codec_error (long ncentroids, long m, const std::vector<float> &v)
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{
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faiss::IndexFlatL2 coarse_quantizer (d);
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faiss::IndexIVFPQ index (&coarse_quantizer, d,
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ncentroids, m, 8);
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index.pq.cp.niter = 10; // speed up train
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index.train (nb, v.data());
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// encode and decode to compute reconstruction error
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std::vector<long> keys (nb);
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std::vector<uint8_t> codes (nb * m);
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index.encode_multiple (nb, keys.data(), v.data(), codes.data(), true);
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std::vector<float> v2 (nb * d);
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index.decode_multiple (nb, keys.data(), codes.data(), v2.data());
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return faiss::fvec_L2sqr (v.data(), v2.data(), nb * d);
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}
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TEST(IVFPQ, codec) {
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std::vector <float> database (nb * d);
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for (size_t i = 0; i < nb * d; i++) {
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database[i] = drand48();
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}
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double err0 = eval_codec_error(16, 8, database);
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// should be more accurate as there are more coarse centroids
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double err1 = eval_codec_error(128, 8, database);
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EXPECT_GT(err0, err1);
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// should be more accurate as there are more PQ codes
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double err2 = eval_codec_error(16, 16, database);
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EXPECT_GT(err0, err2);
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}
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