boost/histogram/accumulators/weighted_sum.hpp
// 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