141 lines
3.8 KiB
C++
141 lines
3.8 KiB
C++
// (C) Copyright Matt Borland 2022
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_STATISTICS_DETAIL_RANK_HPP
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#define BOOST_MATH_STATISTICS_DETAIL_RANK_HPP
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#include <cstdint>
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#include <vector>
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#include <numeric>
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#include <utility>
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#include <iterator>
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#include <algorithm>
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#include <boost/math/tools/config.hpp>
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#ifdef BOOST_MATH_EXEC_COMPATIBLE
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#include <execution>
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#endif
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namespace boost { namespace math { namespace statistics { namespace detail {
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struct pair_equal
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{
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template <typename T1, typename T2>
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bool operator()(const std::pair<T1, T2>& a, const std::pair<T1, T2>& b) const
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{
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return a.first == b.first;
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}
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};
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}}}} // Namespaces
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#ifndef BOOST_MATH_EXEC_COMPATIBLE
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namespace boost { namespace math { namespace statistics { namespace detail {
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template <typename ForwardIterator, typename T = typename std::iterator_traits<ForwardIterator>::value_type>
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auto rank(ForwardIterator first, ForwardIterator last) -> std::vector<std::size_t>
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{
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std::size_t elements = std::distance(first, last);
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std::vector<std::pair<T, std::size_t>> rank_vector(elements);
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std::size_t i = 0;
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while (first != last)
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{
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rank_vector[i] = std::make_pair(*first, i);
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++i;
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++first;
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}
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std::sort(rank_vector.begin(), rank_vector.end());
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// Remove duplicates
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rank_vector.erase(std::unique(rank_vector.begin(), rank_vector.end(), pair_equal()), rank_vector.end());
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elements = rank_vector.size();
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std::pair<T, std::size_t> rank;
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std::vector<std::size_t> result(elements);
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for (i = 0; i < elements; ++i)
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{
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if (rank_vector[i].first != rank.first)
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{
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rank = std::make_pair(rank_vector[i].first, i);
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}
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result[rank_vector[i].second] = rank.second;
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}
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return result;
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}
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template <typename Container>
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inline auto rank(const Container& c) -> std::vector<std::size_t>
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{
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return rank(std::begin(c), std::end(c));
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}
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}}}} // Namespaces
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#else
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namespace boost::math::statistics::detail {
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template <typename ExecutionPolicy, typename ForwardIterator, typename T = typename std::iterator_traits<ForwardIterator>::value_type>
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auto rank(ExecutionPolicy&& exec, ForwardIterator first, ForwardIterator last)
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{
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std::size_t elements = std::distance(first, last);
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std::vector<std::pair<T, std::size_t>> rank_vector(elements);
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std::size_t i = 0;
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while (first != last)
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{
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rank_vector[i] = std::make_pair(*first, i);
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++i;
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++first;
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}
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std::sort(exec, rank_vector.begin(), rank_vector.end());
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// Remove duplicates
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rank_vector.erase(std::unique(exec, rank_vector.begin(), rank_vector.end(), pair_equal()), rank_vector.end());
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elements = rank_vector.size();
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std::pair<T, std::size_t> rank;
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std::vector<std::size_t> result(elements);
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for (i = 0; i < elements; ++i)
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{
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if (rank_vector[i].first != rank.first)
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{
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rank = std::make_pair(rank_vector[i].first, i);
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}
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result[rank_vector[i].second] = rank.second;
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}
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return result;
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}
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template <typename ExecutionPolicy, typename Container>
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inline auto rank(ExecutionPolicy&& exec, const Container& c)
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{
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return rank(exec, std::cbegin(c), std::cend(c));
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}
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template <typename ForwardIterator, typename T = typename std::iterator_traits<ForwardIterator>::value_type>
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inline auto rank(ForwardIterator first, ForwardIterator last)
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{
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return rank(std::execution::seq, first, last);
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}
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template <typename Container>
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inline auto rank(const Container& c)
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{
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return rank(std::execution::seq, std::cbegin(c), std::cend(c));
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}
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} // Namespaces
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#endif // BOOST_MATH_EXEC_COMPATIBLE
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#endif // BOOST_MATH_STATISTICS_DETAIL_RANK_HPP
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