Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // mean.hpp
Chris@16: //
Chris@16: //  Copyright 2005 Eric Niebler. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_ACCUMULATORS_STATISTICS_MEAN_HPP_EAN_28_10_2005
Chris@16: #define BOOST_ACCUMULATORS_STATISTICS_MEAN_HPP_EAN_28_10_2005
Chris@16: 
Chris@16: #include <boost/mpl/placeholders.hpp>
Chris@16: #include <boost/accumulators/framework/accumulator_base.hpp>
Chris@16: #include <boost/accumulators/framework/extractor.hpp>
Chris@16: #include <boost/accumulators/numeric/functional.hpp>
Chris@16: #include <boost/accumulators/framework/parameters/sample.hpp>
Chris@16: #include <boost/accumulators/framework/depends_on.hpp>
Chris@16: #include <boost/accumulators/statistics_fwd.hpp>
Chris@16: #include <boost/accumulators/statistics/count.hpp>
Chris@16: #include <boost/accumulators/statistics/sum.hpp>
Chris@16: 
Chris@16: namespace boost { namespace accumulators
Chris@16: {
Chris@16: 
Chris@16: namespace impl
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////////
Chris@16:     // mean_impl
Chris@16:     //      lazy, by default
Chris@16:     template<typename Sample, typename SumFeature>
Chris@16:     struct mean_impl
Chris@16:       : accumulator_base
Chris@16:     {
Chris@16:         // for boost::result_of
Chris@16:         typedef typename numeric::functional::fdiv<Sample, std::size_t>::result_type result_type;
Chris@16: 
Chris@16:         mean_impl(dont_care) {}
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         result_type result(Args const &args) const
Chris@16:         {
Chris@16:             extractor<SumFeature> sum;
Chris@16:             return numeric::fdiv(sum(args), count(args));
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template<typename Sample, typename Tag>
Chris@16:     struct immediate_mean_impl
Chris@16:       : accumulator_base
Chris@16:     {
Chris@16:         // for boost::result_of
Chris@16:         typedef typename numeric::functional::fdiv<Sample, std::size_t>::result_type result_type;
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         immediate_mean_impl(Args const &args)
Chris@16:           : mean(numeric::fdiv(args[sample | Sample()], numeric::one<std::size_t>::value))
Chris@16:         {
Chris@16:         }
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         void operator ()(Args const &args)
Chris@16:         {
Chris@16:             std::size_t cnt = count(args);
Chris@16:             this->mean = numeric::fdiv(
Chris@16:                 (this->mean * (cnt - 1)) + args[parameter::keyword<Tag>::get()]
Chris@16:               , cnt
Chris@16:             );
Chris@16:         }
Chris@16: 
Chris@16:         result_type result(dont_care) const
Chris@16:         {
Chris@16:             return this->mean;
Chris@16:         }
Chris@16: 
Chris@16:     private:
Chris@16:         result_type mean;
Chris@16:     };
Chris@16: 
Chris@16: } // namespace impl
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // tag::mean
Chris@16: // tag::immediate_mean
Chris@16: // tag::mean_of_weights
Chris@16: // tag::immediate_mean_of_weights
Chris@16: // tag::mean_of_variates
Chris@16: // tag::immediate_mean_of_variates
Chris@16: //
Chris@16: namespace tag
Chris@16: {
Chris@16:     struct mean
Chris@16:       : depends_on<count, sum>
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef accumulators::impl::mean_impl<mpl::_1, sum> impl;
Chris@16:     };
Chris@16:     struct immediate_mean
Chris@16:       : depends_on<count>
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef accumulators::impl::immediate_mean_impl<mpl::_1, tag::sample> impl;
Chris@16:     };
Chris@16:     struct mean_of_weights
Chris@16:       : depends_on<count, sum_of_weights>
Chris@16:     {
Chris@16:         typedef mpl::true_ is_weight_accumulator;
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef accumulators::impl::mean_impl<mpl::_2, sum_of_weights> impl;
Chris@16:     };
Chris@16:     struct immediate_mean_of_weights
Chris@16:       : depends_on<count>
Chris@16:     {
Chris@16:         typedef mpl::true_ is_weight_accumulator;
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef accumulators::impl::immediate_mean_impl<mpl::_2, tag::weight> impl;
Chris@16:     };
Chris@16:     template<typename VariateType, typename VariateTag>
Chris@16:     struct mean_of_variates
Chris@16:       : depends_on<count, sum_of_variates<VariateType, VariateTag> >
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef mpl::always<accumulators::impl::mean_impl<VariateType, sum_of_variates<VariateType, VariateTag> > > impl;
Chris@16:     };
Chris@16:     template<typename VariateType, typename VariateTag>
Chris@16:     struct immediate_mean_of_variates
Chris@16:       : depends_on<count>
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef mpl::always<accumulators::impl::immediate_mean_impl<VariateType, VariateTag> > impl;
Chris@16:     };
Chris@16: }
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // extract::mean
Chris@16: // extract::mean_of_weights
Chris@16: // extract::mean_of_variates
Chris@16: //
Chris@16: namespace extract
Chris@16: {
Chris@16:     extractor<tag::mean> const mean = {};
Chris@16:     extractor<tag::mean_of_weights> const mean_of_weights = {};
Chris@16:     BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, mean_of_variates, (typename)(typename))
Chris@16: 
Chris@16:     BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean)
Chris@16:     BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean_of_weights)
Chris@16: }
Chris@16: 
Chris@16: using extract::mean;
Chris@16: using extract::mean_of_weights;
Chris@16: using extract::mean_of_variates;
Chris@16: 
Chris@16: // mean(lazy) -> mean
Chris@16: template<>
Chris@16: struct as_feature<tag::mean(lazy)>
Chris@16: {
Chris@16:     typedef tag::mean type;
Chris@16: };
Chris@16: 
Chris@16: // mean(immediate) -> immediate_mean
Chris@16: template<>
Chris@16: struct as_feature<tag::mean(immediate)>
Chris@16: {
Chris@16:     typedef tag::immediate_mean type;
Chris@16: };
Chris@16: 
Chris@16: // mean_of_weights(lazy) -> mean_of_weights
Chris@16: template<>
Chris@16: struct as_feature<tag::mean_of_weights(lazy)>
Chris@16: {
Chris@16:     typedef tag::mean_of_weights type;
Chris@16: };
Chris@16: 
Chris@16: // mean_of_weights(immediate) -> immediate_mean_of_weights
Chris@16: template<>
Chris@16: struct as_feature<tag::mean_of_weights(immediate)>
Chris@16: {
Chris@16:     typedef tag::immediate_mean_of_weights type;
Chris@16: };
Chris@16: 
Chris@16: // mean_of_variates<VariateType, VariateTag>(lazy) -> mean_of_variates<VariateType, VariateTag>
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(lazy)>
Chris@16: {
Chris@16:     typedef tag::mean_of_variates<VariateType, VariateTag> type;
Chris@16: };
Chris@16: 
Chris@16: // mean_of_variates<VariateType, VariateTag>(immediate) -> immediate_mean_of_variates<VariateType, VariateTag>
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(immediate)>
Chris@16: {
Chris@16:     typedef tag::immediate_mean_of_variates<VariateType, VariateTag> type;
Chris@16: };
Chris@16: 
Chris@16: // for the purposes of feature-based dependency resolution,
Chris@16: // immediate_mean provides the same feature as mean
Chris@16: template<>
Chris@16: struct feature_of<tag::immediate_mean>
Chris@16:   : feature_of<tag::mean>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: // for the purposes of feature-based dependency resolution,
Chris@16: // immediate_mean provides the same feature as mean
Chris@16: template<>
Chris@16: struct feature_of<tag::immediate_mean_of_weights>
Chris@16:   : feature_of<tag::mean_of_weights>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: // for the purposes of feature-based dependency resolution,
Chris@16: // immediate_mean provides the same feature as mean
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
Chris@16:   : feature_of<tag::mean_of_variates<VariateType, VariateTag> >
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: // So that mean can be automatically substituted with
Chris@16: // weighted_mean when the weight parameter is non-void.
Chris@16: template<>
Chris@16: struct as_weighted_feature<tag::mean>
Chris@16: {
Chris@16:     typedef tag::weighted_mean type;
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct feature_of<tag::weighted_mean>
Chris@16:   : feature_of<tag::mean>
Chris@16: {};
Chris@16: 
Chris@16: // So that immediate_mean can be automatically substituted with
Chris@16: // immediate_weighted_mean when the weight parameter is non-void.
Chris@16: template<>
Chris@16: struct as_weighted_feature<tag::immediate_mean>
Chris@16: {
Chris@16:     typedef tag::immediate_weighted_mean type;
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct feature_of<tag::immediate_weighted_mean>
Chris@16:   : feature_of<tag::immediate_mean>
Chris@16: {};
Chris@16: 
Chris@16: // So that mean_of_weights<> can be automatically substituted with
Chris@16: // weighted_mean_of_variates<> when the weight parameter is non-void.
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct as_weighted_feature<tag::mean_of_variates<VariateType, VariateTag> >
Chris@16: {
Chris@16:     typedef tag::weighted_mean_of_variates<VariateType, VariateTag> type;
Chris@16: };
Chris@16: 
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct feature_of<tag::weighted_mean_of_variates<VariateType, VariateTag> >
Chris@16:   : feature_of<tag::mean_of_variates<VariateType, VariateTag> >
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: // So that immediate_mean_of_weights<> can be automatically substituted with
Chris@16: // immediate_weighted_mean_of_variates<> when the weight parameter is non-void.
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct as_weighted_feature<tag::immediate_mean_of_variates<VariateType, VariateTag> >
Chris@16: {
Chris@16:     typedef tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> type;
Chris@16: };
Chris@16: 
Chris@16: template<typename VariateType, typename VariateTag>
Chris@16: struct feature_of<tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> >
Chris@16:   : feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: ////////////////////////////////////////////////////////////////////////////
Chris@16: //// droppable_accumulator<mean_impl>
Chris@16: ////  need to specialize droppable lazy mean to cache the result at the
Chris@16: ////  point the accumulator is dropped.
Chris@16: ///// INTERNAL ONLY
Chris@16: /////
Chris@16: //template<typename Sample, typename SumFeature>
Chris@16: //struct droppable_accumulator<impl::mean_impl<Sample, SumFeature> >
Chris@16: //  : droppable_accumulator_base<
Chris@16: //        with_cached_result<impl::mean_impl<Sample, SumFeature> >
Chris@16: //    >
Chris@16: //{
Chris@16: //    template<typename Args>
Chris@16: //    droppable_accumulator(Args const &args)
Chris@16: //      : droppable_accumulator::base(args)
Chris@16: //    {
Chris@16: //    }
Chris@16: //};
Chris@16: 
Chris@16: }} // namespace boost::accumulators
Chris@16: 
Chris@16: #endif