boost/accumulators/statistics/mean.hpp
///////////////////////////////////////////////////////////////////////////////
// mean.hpp
//
// Copyright 2005 Eric Niebler. 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_MEAN_HPP_EAN_28_10_2005
#define BOOST_ACCUMULATORS_STATISTICS_MEAN_HPP_EAN_28_10_2005
#include <boost/mpl/placeholders.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/sum.hpp>
namespace boost { namespace accumulators
{
namespace impl
{
///////////////////////////////////////////////////////////////////////////////
// mean_impl
// lazy, by default
template<typename Sample, typename SumFeature>
struct mean_impl
: accumulator_base
{
// for boost::result_of
typedef typename numeric::functional::fdiv<Sample, std::size_t>::result_type result_type;
mean_impl(dont_care) {}
template<typename Args>
result_type result(Args const &args) const
{
extractor<SumFeature> sum;
return numeric::fdiv(sum(args), count(args));
}
// serialization is done by accumulators it depends on
template<class Archive>
void serialize(Archive & /* ar */, const unsigned int /* file_version */) {}
};
template<typename Sample, typename Tag>
struct immediate_mean_impl
: accumulator_base
{
// for boost::result_of
typedef typename numeric::functional::fdiv<Sample, std::size_t>::result_type result_type;
template<typename Args>
immediate_mean_impl(Args const &args)
: mean(numeric::fdiv(args[sample | Sample()], numeric::one<std::size_t>::value))
{
}
template<typename Args>
void operator ()(Args const &args)
{
std::size_t cnt = count(args);
this->mean = numeric::fdiv(
(this->mean * (cnt - 1)) + args[parameter::keyword<Tag>::get()]
, cnt
);
}
result_type result(dont_care) const
{
return this->mean;
}
template<class Archive>
void serialize(Archive & ar, const unsigned int /* file_version */)
{
ar & mean;
}
private:
result_type mean;
};
} // namespace impl
///////////////////////////////////////////////////////////////////////////////
// tag::mean
// tag::immediate_mean
// tag::mean_of_weights
// tag::immediate_mean_of_weights
// tag::mean_of_variates
// tag::immediate_mean_of_variates
//
namespace tag
{
struct mean
: depends_on<count, sum>
{
/// INTERNAL ONLY
///
typedef accumulators::impl::mean_impl<mpl::_1, sum> impl;
};
struct immediate_mean
: depends_on<count>
{
/// INTERNAL ONLY
///
typedef accumulators::impl::immediate_mean_impl<mpl::_1, tag::sample> impl;
};
struct mean_of_weights
: depends_on<count, sum_of_weights>
{
typedef mpl::true_ is_weight_accumulator;
/// INTERNAL ONLY
///
typedef accumulators::impl::mean_impl<mpl::_2, sum_of_weights> impl;
};
struct immediate_mean_of_weights
: depends_on<count>
{
typedef mpl::true_ is_weight_accumulator;
/// INTERNAL ONLY
///
typedef accumulators::impl::immediate_mean_impl<mpl::_2, tag::weight> impl;
};
template<typename VariateType, typename VariateTag>
struct mean_of_variates
: depends_on<count, sum_of_variates<VariateType, VariateTag> >
{
/// INTERNAL ONLY
///
typedef mpl::always<accumulators::impl::mean_impl<VariateType, sum_of_variates<VariateType, VariateTag> > > impl;
};
template<typename VariateType, typename VariateTag>
struct immediate_mean_of_variates
: depends_on<count>
{
/// INTERNAL ONLY
///
typedef mpl::always<accumulators::impl::immediate_mean_impl<VariateType, VariateTag> > impl;
};
}
///////////////////////////////////////////////////////////////////////////////
// extract::mean
// extract::mean_of_weights
// extract::mean_of_variates
//
namespace extract
{
extractor<tag::mean> const mean = {};
extractor<tag::mean_of_weights> const mean_of_weights = {};
BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, mean_of_variates, (typename)(typename))
BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean)
BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean_of_weights)
}
using extract::mean;
using extract::mean_of_weights;
using extract::mean_of_variates;
// mean(lazy) -> mean
template<>
struct as_feature<tag::mean(lazy)>
{
typedef tag::mean type;
};
// mean(immediate) -> immediate_mean
template<>
struct as_feature<tag::mean(immediate)>
{
typedef tag::immediate_mean type;
};
// mean_of_weights(lazy) -> mean_of_weights
template<>
struct as_feature<tag::mean_of_weights(lazy)>
{
typedef tag::mean_of_weights type;
};
// mean_of_weights(immediate) -> immediate_mean_of_weights
template<>
struct as_feature<tag::mean_of_weights(immediate)>
{
typedef tag::immediate_mean_of_weights type;
};
// mean_of_variates<VariateType, VariateTag>(lazy) -> mean_of_variates<VariateType, VariateTag>
template<typename VariateType, typename VariateTag>
struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(lazy)>
{
typedef tag::mean_of_variates<VariateType, VariateTag> type;
};
// mean_of_variates<VariateType, VariateTag>(immediate) -> immediate_mean_of_variates<VariateType, VariateTag>
template<typename VariateType, typename VariateTag>
struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(immediate)>
{
typedef tag::immediate_mean_of_variates<VariateType, VariateTag> type;
};
// for the purposes of feature-based dependency resolution,
// immediate_mean provides the same feature as mean
template<>
struct feature_of<tag::immediate_mean>
: feature_of<tag::mean>
{
};
// for the purposes of feature-based dependency resolution,
// immediate_mean provides the same feature as mean
template<>
struct feature_of<tag::immediate_mean_of_weights>
: feature_of<tag::mean_of_weights>
{
};
// for the purposes of feature-based dependency resolution,
// immediate_mean provides the same feature as mean
template<typename VariateType, typename VariateTag>
struct feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
: feature_of<tag::mean_of_variates<VariateType, VariateTag> >
{
};
// So that mean can be automatically substituted with
// weighted_mean when the weight parameter is non-void.
template<>
struct as_weighted_feature<tag::mean>
{
typedef tag::weighted_mean type;
};
template<>
struct feature_of<tag::weighted_mean>
: feature_of<tag::mean>
{};
// So that immediate_mean can be automatically substituted with
// immediate_weighted_mean when the weight parameter is non-void.
template<>
struct as_weighted_feature<tag::immediate_mean>
{
typedef tag::immediate_weighted_mean type;
};
template<>
struct feature_of<tag::immediate_weighted_mean>
: feature_of<tag::immediate_mean>
{};
// So that mean_of_weights<> can be automatically substituted with
// weighted_mean_of_variates<> when the weight parameter is non-void.
template<typename VariateType, typename VariateTag>
struct as_weighted_feature<tag::mean_of_variates<VariateType, VariateTag> >
{
typedef tag::weighted_mean_of_variates<VariateType, VariateTag> type;
};
template<typename VariateType, typename VariateTag>
struct feature_of<tag::weighted_mean_of_variates<VariateType, VariateTag> >
: feature_of<tag::mean_of_variates<VariateType, VariateTag> >
{
};
// So that immediate_mean_of_weights<> can be automatically substituted with
// immediate_weighted_mean_of_variates<> when the weight parameter is non-void.
template<typename VariateType, typename VariateTag>
struct as_weighted_feature<tag::immediate_mean_of_variates<VariateType, VariateTag> >
{
typedef tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> type;
};
template<typename VariateType, typename VariateTag>
struct feature_of<tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> >
: feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
{
};
////////////////////////////////////////////////////////////////////////////
//// droppable_accumulator<mean_impl>
//// need to specialize droppable lazy mean to cache the result at the
//// point the accumulator is dropped.
///// INTERNAL ONLY
/////
//template<typename Sample, typename SumFeature>
//struct droppable_accumulator<impl::mean_impl<Sample, SumFeature> >
// : droppable_accumulator_base<
// with_cached_result<impl::mean_impl<Sample, SumFeature> >
// >
//{
// template<typename Args>
// droppable_accumulator(Args const &args)
// : droppable_accumulator::base(args)
// {
// }
//};
}} // namespace boost::accumulators
#endif