214 line
6.6 KiB
C++
214 line
6.6 KiB
C++
/**
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* \file v1.hpp
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* \brief
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*
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* \author
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* Christos Choutouridis AEM:8997
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* <cchoutou@ece.auth.gr>
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*/
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#ifndef V1_HPP_
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#define V1_HPP_
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#include <vector>
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#include <algorithm>
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#include "matrix.hpp"
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#include "v0.hpp"
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#include "config.h"
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#if defined CILK
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#include <cilk/cilk.h>
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#include <cilk/cilk_api.h>
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//#include <cilk/reducer_opadd.h>
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#elif defined OMP
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#include <omp.h>
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#elif defined PTHREADS
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#include <thread>
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#include <numeric>
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#include <functional>
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//#include <random>
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#else
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#endif
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void init_workers();
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namespace v1 {
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/*!
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*
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* Merge knnsearch results and select the closest neighbors
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*
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* \tparam DataType
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* \tparam IndexType
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* \param N1 Neighbors results from one knnsearch
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* \param D1 Distances results from one knnsearcs
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* \param N2 Neighbors results from second knnsearch
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* \param D2 Distances results from second knnsearch
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* \param k How many
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* \param m How accurate
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* \param N Output for Neighbors
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* \param D Output for Distances
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*/
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template <typename DataType, typename IndexType>
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void mergeResultsWithM(mtx::Matrix<IndexType>& N1, mtx::Matrix<DataType>& D1,
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mtx::Matrix<IndexType>& N2, mtx::Matrix<DataType>& D2,
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size_t k, size_t m,
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mtx::Matrix<IndexType>& N, mtx::Matrix<DataType>& D) {
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size_t numQueries = N1.rows();
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size_t maxCandidates = std::min((IndexType)m, (IndexType)(N1.columns() + N2.columns()));
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for (size_t q = 0; q < numQueries; ++q) {
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// Combine distances and neighbors
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std::vector<std::pair<DataType, IndexType>> candidates(N1.columns() + N2.columns());
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// Concatenate N1 and N2 rows
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for (size_t i = 0; i < N1.columns(); ++i) {
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candidates[i] = {D1.get(q, i), N1.get(q, i)};
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}
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for (size_t i = 0; i < N2.columns(); ++i) {
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candidates[i + N1.columns()] = {D2.get(q, i), N2.get(q, i)};
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}
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// Keep only the top-m candidates
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v0::quickselect(candidates, maxCandidates);
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// Sort the top-m candidates
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std::sort(candidates.begin(), candidates.begin() + maxCandidates);
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// If m < k, pad the remaining slots with invalid values
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for (size_t i = 0; i < k; ++i) {
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if (i < maxCandidates) {
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D.set(candidates[i].first, q, i);
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N.set(candidates[i].second, q, i);
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} else {
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D.set(std::numeric_limits<DataType>::infinity(), q, i);
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N.set(static_cast<IndexType>(-1), q, i); // Invalid index (end)
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}
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}
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}
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}
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/*!
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* The main parallelizable body
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*/
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template<typename MatrixD, typename MatrixI>
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void worker_body (std::vector<MatrixD>& corpus_slices,
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std::vector<MatrixD>& query_slices,
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MatrixI& idx,
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MatrixD& dst,
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size_t slice,
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size_t num_slices, size_t corpus_slice_size, size_t query_slice_size,
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size_t k,
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size_t m) {
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// "load" types
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using DstType = typename MatrixD::dataType;
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using IdxType = typename MatrixI::dataType;
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for (size_t ci = 0; ci < num_slices; ++ci) {
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size_t idx_offset = ci * corpus_slice_size;
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// Intermediate matrixes for intermediate results
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MatrixI temp_idx(query_slices[slice].rows(), k);
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MatrixD temp_dst(query_slices[slice].rows(), k);
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// kNN for each combination
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v0::knnsearch(corpus_slices[ci], query_slices[slice], idx_offset, k, m, temp_idx, temp_dst);
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// Merge temporary results to final results
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MatrixI idx_slice((IdxType*)idx.data(), slice * query_slice_size, query_slices[slice].rows(), k);
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MatrixD dst_slice((DstType*)dst.data(), slice * query_slice_size, query_slices[slice].rows(), k);
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mergeResultsWithM(idx_slice, dst_slice, temp_idx, temp_dst, k, m, idx_slice, dst_slice);
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}
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}
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/*!
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* \param C Is a MxD matrix (Corpus)
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* \param Q Is a NxD matrix (Query)
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* \param num_slices How many slices to Corpus-Query
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* \param k The number of nearest neighbors needed
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* \param m accuracy
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* \param idx Is the Nxk matrix with the k indexes of the C points, that are
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* neighbors of the nth point of Q
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* \param dst Is the Nxk matrix with the k distances to the C points of the nth
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* point of Q
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*/
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template<typename MatrixD, typename MatrixI>
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void knnsearch(MatrixD& C, MatrixD& Q, size_t num_slices, size_t k, size_t m, MatrixI& idx, MatrixD& dst) {
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using DstType = typename MatrixD::dataType;
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using IdxType = typename MatrixI::dataType;
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//Slice calculations
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size_t corpus_slice_size = C.rows() / ((num_slices == 0)? 1:num_slices);
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size_t query_slice_size = Q.rows() / ((num_slices == 0)? 1:num_slices);
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// Make slices
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std::vector<MatrixD> corpus_slices;
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std::vector<MatrixD> query_slices;
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for (size_t i = 0; i < num_slices; ++i) {
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corpus_slices.emplace_back(
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(DstType*)C.data(),
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i * corpus_slice_size,
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(i == num_slices - 1 ? C.rows() - i * corpus_slice_size : corpus_slice_size),
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C.columns());
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query_slices.emplace_back(
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(DstType*)Q.data(),
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i * query_slice_size,
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(i == num_slices - 1 ? Q.rows() - i * query_slice_size : query_slice_size),
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Q.columns());
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}
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// Initialize results
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for (size_t i = 0; i < dst.rows(); ++i) {
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for (size_t j = 0; j < dst.columns(); ++j) {
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dst.set(std::numeric_limits<DstType>::infinity(), i, j);
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idx.set(static_cast<IdxType>(-1), i, j);
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}
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}
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// Main loop
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#if defined OMP
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#pragma omp parallel for
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for (size_t qi = 0; qi < num_slices; ++qi) {
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worker_body (corpus_slices, query_slices, idx, dst, qi, num_slices, corpus_slice_size, query_slice_size, k, m);
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}
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#elif defined CILK
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cilk_for (size_t qi = 0; qi < num_slices; ++qi) {
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worker_body (corpus_slices, query_slices, idx, dst, qi, num_slices, corpus_slice_size, query_slice_size, k, m);
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}
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#elif defined PTHREADS
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std::vector<std::thread> workers;
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for (size_t qi = 0; qi < num_slices; ++qi) {
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workers.push_back(
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std::thread (worker_body<MatrixD, MatrixI>,
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std::ref(corpus_slices), std::ref(query_slices),
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std::ref(idx), std::ref(dst),
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qi,
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num_slices, corpus_slice_size, query_slice_size,
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k, m)
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);
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}
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// Join threads
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std::for_each(workers.begin(), workers.end(), [](std::thread& t){
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t.join();
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});
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#else
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for (size_t qi = 0; qi < num_slices; ++qi) {
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worker_body (corpus_slices, query_slices, idx, dst, qi, num_slices, corpus_slice_size, query_slice_size, k, m);
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}
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#endif
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}
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} // namespace v1
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#endif /* V1_HPP_ */
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