boost/accumulators/statistics/weighted_moment.hpp
///////////////////////////////////////////////////////////////////////////////
// weighted_moment.hpp
//
// Copyright 2006, Eric Niebler, Olivier Gygi. 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_ACCUMULATORS_STATISTICS_WEIGHTED_MOMENT_HPP_EAN_15_11_2005
#define BOOST_ACCUMULATORS_STATISTICS_WEIGHTED_MOMENT_HPP_EAN_15_11_2005
#include <boost/config/no_tr1/cmath.hpp>
#include <boost/mpl/int.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/preprocessor/arithmetic/inc.hpp>
#include <boost/preprocessor/repetition/repeat_from_to.hpp>
#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
#include <boost/preprocessor/repetition/enum_trailing_binary_params.hpp>
#include <boost/accumulators/framework/accumulator_base.hpp>
#include <boost/accumulators/framework/extractor.hpp>
#include <boost/accumulators/numeric/functional.hpp>
#include <boost/accumulators/framework/parameters/sample.hpp>
#include <boost/accumulators/framework/depends_on.hpp>
#include <boost/accumulators/statistics_fwd.hpp>
#include <boost/accumulators/statistics/count.hpp>
#include <boost/accumulators/statistics/moment.hpp> // for pow()
#include <boost/accumulators/statistics/sum.hpp>
namespace boost { namespace accumulators
{
namespace impl
{
///////////////////////////////////////////////////////////////////////////////
// weighted_moment_impl
template<typename N, typename Sample, typename Weight>
struct weighted_moment_impl
: accumulator_base // TODO: also depends_on sum of powers
{
BOOST_MPL_ASSERT_RELATION(N::value, >, 0);
typedef typename numeric::functional::multiplies<Sample, Weight>::result_type weighted_sample;
// for boost::result_of
typedef typename numeric::functional::fdiv<weighted_sample, Weight>::result_type result_type;
template<typename Args>
weighted_moment_impl(Args const &args)
: sum(args[sample | Sample()] * numeric::one<Weight>::value)
{
}
template<typename Args>
void operator ()(Args const &args)
{
this->sum += args[weight] * numeric::pow(args[sample], N());
}
template<typename Args>
result_type result(Args const &args) const
{
return numeric::fdiv(this->sum, sum_of_weights(args));
}
private:
weighted_sample sum;
};
} // namespace impl
///////////////////////////////////////////////////////////////////////////////
// tag::weighted_moment
//
namespace tag
{
template<int N>
struct weighted_moment
: depends_on<count, sum_of_weights>
{
/// INTERNAL ONLY
///
typedef accumulators::impl::weighted_moment_impl<mpl::int_<N>, mpl::_1, mpl::_2> impl;
};
}
///////////////////////////////////////////////////////////////////////////////
// extract::weighted_moment
//
namespace extract
{
BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, weighted_moment, (int))
}
using extract::weighted_moment;
}} // namespace boost::accumulators
#endif