79 lines
1.9 KiB
C++
79 lines
1.9 KiB
C++
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT 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 <omp.h>
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#include <cstdio>
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#include <faiss/impl/ScalarQuantizer.h>
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#include <faiss/utils/distances.h>
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#include <faiss/utils/random.h>
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#include <faiss/utils/utils.h>
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using namespace faiss;
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int main() {
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int d = 128;
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int n = 2000;
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std::vector<float> x(d * n);
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float_rand(x.data(), d * n, 12345);
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// make sure it's idempotent
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ScalarQuantizer sq(d, ScalarQuantizer::QT_6bit);
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omp_set_num_threads(1);
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sq.train(n, x.data());
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size_t code_size = sq.code_size;
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printf("code size: %ld\n", sq.code_size);
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// encode
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std::vector<uint8_t> codes(code_size * n);
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sq.compute_codes(x.data(), codes.data(), n);
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// decode
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std::vector<float> x2(d * n);
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sq.decode(codes.data(), x2.data(), n);
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printf("sqL2 recons error: %g\n",
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fvec_L2sqr(x.data(), x2.data(), n * d) / n);
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// encode again
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std::vector<uint8_t> codes2(code_size * n);
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sq.compute_codes(x2.data(), codes2.data(), n);
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size_t ndiff = 0;
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for (size_t i = 0; i < codes.size(); i++) {
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if (codes[i] != codes2[i])
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ndiff++;
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}
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printf("ndiff for idempotence: %ld / %ld\n", ndiff, codes.size());
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std::unique_ptr<ScalarQuantizer::SQDistanceComputer> dc(
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sq.get_distance_computer());
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dc->codes = codes.data();
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dc->code_size = sq.code_size;
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printf("code size: %ld\n", dc->code_size);
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double sum_dis = 0;
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double t0 = getmillisecs();
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for (int i = 0; i < n; i++) {
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dc->set_query(&x[i * d]);
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for (int j = 0; j < n; j++) {
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sum_dis += (*dc)(j);
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}
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}
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printf("distances computed in %.3f ms, checksum=%g\n",
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getmillisecs() - t0,
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sum_dis);
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return 0;
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}
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