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- // Copyright 2015-2018 Hans Dembinski
- //
- // Distributed under the Boost Software License, version 1.0.
- // (See accompanying file LICENSE_1_0.txt
- // or copy at http://www.boost.org/LICENSE_1_0.txt)
- #ifndef BOOST_HISTOGRAM_ACCUMULATORS_WEIGHTED_SUM_HPP
- #define BOOST_HISTOGRAM_ACCUMULATORS_WEIGHTED_SUM_HPP
- #include <boost/core/nvp.hpp>
- #include <boost/histogram/fwd.hpp> // for weighted_sum<>
- #include <type_traits>
- namespace boost {
- namespace histogram {
- namespace accumulators {
- /// Holds sum of weights and its variance estimate
- template <typename RealType>
- class weighted_sum {
- public:
- weighted_sum() = default;
- explicit weighted_sum(const RealType& value) noexcept
- : sum_of_weights_(value), sum_of_weights_squared_(value) {}
- weighted_sum(const RealType& value, const RealType& variance) noexcept
- : sum_of_weights_(value), sum_of_weights_squared_(variance) {}
- /// Increment by one.
- weighted_sum& operator++() { return operator+=(1); }
- /// Increment by value.
- template <typename T>
- weighted_sum& operator+=(const T& value) {
- sum_of_weights_ += value;
- sum_of_weights_squared_ += value * value;
- return *this;
- }
- /// Added another weighted sum.
- template <typename T>
- weighted_sum& operator+=(const weighted_sum<T>& rhs) {
- sum_of_weights_ += static_cast<RealType>(rhs.sum_of_weights_);
- sum_of_weights_squared_ += static_cast<RealType>(rhs.sum_of_weights_squared_);
- return *this;
- }
- /// Scale by value.
- weighted_sum& operator*=(const RealType& x) {
- sum_of_weights_ *= x;
- sum_of_weights_squared_ *= x * x;
- return *this;
- }
- bool operator==(const RealType& rhs) const noexcept {
- return sum_of_weights_ == rhs && sum_of_weights_squared_ == rhs;
- }
- template <typename T>
- bool operator==(const weighted_sum<T>& rhs) const noexcept {
- return sum_of_weights_ == rhs.sum_of_weights_ &&
- sum_of_weights_squared_ == rhs.sum_of_weights_squared_;
- }
- template <typename T>
- bool operator!=(const T& rhs) const noexcept {
- return !operator==(rhs);
- }
- /// Return value of the sum.
- const RealType& value() const noexcept { return sum_of_weights_; }
- /// Return estimated variance of the sum.
- const RealType& variance() const noexcept { return sum_of_weights_squared_; }
- // lossy conversion must be explicit
- template <class T>
- explicit operator T() const {
- return static_cast<T>(sum_of_weights_);
- }
- template <class Archive>
- void serialize(Archive& ar, unsigned /* version */) {
- ar& make_nvp("sum_of_weights", sum_of_weights_);
- ar& make_nvp("sum_of_weights_squared", sum_of_weights_squared_);
- }
- private:
- RealType sum_of_weights_ = RealType();
- RealType sum_of_weights_squared_ = RealType();
- };
- } // namespace accumulators
- } // namespace histogram
- } // namespace boost
- #ifndef BOOST_HISTOGRAM_DOXYGEN_INVOKED
- namespace std {
- template <class T, class U>
- struct common_type<boost::histogram::accumulators::weighted_sum<T>,
- boost::histogram::accumulators::weighted_sum<U>> {
- using type = boost::histogram::accumulators::weighted_sum<common_type_t<T, U>>;
- };
- template <class T, class U>
- struct common_type<boost::histogram::accumulators::weighted_sum<T>, U> {
- using type = boost::histogram::accumulators::weighted_sum<common_type_t<T, U>>;
- };
- template <class T, class U>
- struct common_type<T, boost::histogram::accumulators::weighted_sum<U>> {
- using type = boost::histogram::accumulators::weighted_sum<common_type_t<T, U>>;
- };
- } // namespace std
- #endif
- #endif
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