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/Src/Dependencies/Boost/boost/accumulators/statistics/mean.hpp

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  1///////////////////////////////////////////////////////////////////////////////
  2// mean.hpp
  3//
  4//  Copyright 2005 Eric Niebler. Distributed under the Boost
  5//  Software License, Version 1.0. (See accompanying file
  6//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  7
  8#ifndef BOOST_ACCUMULATORS_STATISTICS_MEAN_HPP_EAN_28_10_2005
  9#define BOOST_ACCUMULATORS_STATISTICS_MEAN_HPP_EAN_28_10_2005
 10
 11#include <boost/mpl/placeholders.hpp>
 12#include <boost/accumulators/framework/accumulator_base.hpp>
 13#include <boost/accumulators/framework/extractor.hpp>
 14#include <boost/accumulators/numeric/functional.hpp>
 15#include <boost/accumulators/framework/parameters/sample.hpp>
 16#include <boost/accumulators/framework/depends_on.hpp>
 17#include <boost/accumulators/statistics_fwd.hpp>
 18#include <boost/accumulators/statistics/count.hpp>
 19#include <boost/accumulators/statistics/sum.hpp>
 20
 21namespace boost { namespace accumulators
 22{
 23
 24namespace impl
 25{
 26    ///////////////////////////////////////////////////////////////////////////////
 27    // mean_impl
 28    //      lazy, by default
 29    template<typename Sample, typename SumFeature>
 30    struct mean_impl
 31      : accumulator_base
 32    {
 33        // for boost::result_of
 34        typedef typename numeric::functional::average<Sample, std::size_t>::result_type result_type;
 35
 36        mean_impl(dont_care) {}
 37
 38        template<typename Args>
 39        result_type result(Args const &args) const
 40        {
 41            extractor<SumFeature> sum;
 42            return numeric::average(sum(args), count(args));
 43        }
 44    };
 45
 46    template<typename Sample, typename Tag>
 47    struct immediate_mean_impl
 48      : accumulator_base
 49    {
 50        // for boost::result_of
 51        typedef typename numeric::functional::average<Sample, std::size_t>::result_type result_type;
 52
 53        template<typename Args>
 54        immediate_mean_impl(Args const &args)
 55          : mean(numeric::average(args[sample | Sample()], numeric::one<std::size_t>::value))
 56        {
 57        }
 58
 59        template<typename Args>
 60        void operator ()(Args const &args)
 61        {
 62            std::size_t cnt = count(args);
 63            this->mean = numeric::average(
 64                (this->mean * (cnt - 1)) + args[parameter::keyword<Tag>::get()]
 65              , cnt
 66            );
 67        }
 68
 69        result_type result(dont_care) const
 70        {
 71            return this->mean;
 72        }
 73
 74    private:
 75        result_type mean;
 76    };
 77
 78} // namespace impl
 79
 80///////////////////////////////////////////////////////////////////////////////
 81// tag::mean
 82// tag::immediate_mean
 83// tag::mean_of_weights
 84// tag::immediate_mean_of_weights
 85// tag::mean_of_variates
 86// tag::immediate_mean_of_variates
 87//
 88namespace tag
 89{
 90    struct mean
 91      : depends_on<count, sum>
 92    {
 93        /// INTERNAL ONLY
 94        ///
 95        typedef accumulators::impl::mean_impl<mpl::_1, sum> impl;
 96    };
 97    struct immediate_mean
 98      : depends_on<count>
 99    {
100        /// INTERNAL ONLY
101        ///
102        typedef accumulators::impl::immediate_mean_impl<mpl::_1, tag::sample> impl;
103    };
104    struct mean_of_weights
105      : depends_on<count, sum_of_weights>
106    {
107        typedef mpl::true_ is_weight_accumulator;
108        /// INTERNAL ONLY
109        ///
110        typedef accumulators::impl::mean_impl<mpl::_2, sum_of_weights> impl;
111    };
112    struct immediate_mean_of_weights
113      : depends_on<count>
114    {
115        typedef mpl::true_ is_weight_accumulator;
116        /// INTERNAL ONLY
117        ///
118        typedef accumulators::impl::immediate_mean_impl<mpl::_2, tag::weight> impl;
119    };
120    template<typename VariateType, typename VariateTag>
121    struct mean_of_variates
122      : depends_on<count, sum_of_variates<VariateType, VariateTag> >
123    {
124        /// INTERNAL ONLY
125        ///
126        typedef mpl::always<accumulators::impl::mean_impl<VariateType, sum_of_variates<VariateType, VariateTag> > > impl;
127    };
128    template<typename VariateType, typename VariateTag>
129    struct immediate_mean_of_variates
130      : depends_on<count>
131    {
132        /// INTERNAL ONLY
133        ///
134        typedef mpl::always<accumulators::impl::immediate_mean_impl<VariateType, VariateTag> > impl;
135    };
136}
137
138///////////////////////////////////////////////////////////////////////////////
139// extract::mean
140// extract::mean_of_weights
141// extract::mean_of_variates
142//
143namespace extract
144{
145    extractor<tag::mean> const mean = {};
146    extractor<tag::mean_of_weights> const mean_of_weights = {};
147    BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, mean_of_variates, (typename)(typename))
148
149    BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean)
150    BOOST_ACCUMULATORS_IGNORE_GLOBAL(mean_of_weights)
151}
152
153using extract::mean;
154using extract::mean_of_weights;
155using extract::mean_of_variates;
156
157// mean(lazy) -> mean
158template<>
159struct as_feature<tag::mean(lazy)>
160{
161    typedef tag::mean type;
162};
163
164// mean(immediate) -> immediate_mean
165template<>
166struct as_feature<tag::mean(immediate)>
167{
168    typedef tag::immediate_mean type;
169};
170
171// mean_of_weights(lazy) -> mean_of_weights
172template<>
173struct as_feature<tag::mean_of_weights(lazy)>
174{
175    typedef tag::mean_of_weights type;
176};
177
178// mean_of_weights(immediate) -> immediate_mean_of_weights
179template<>
180struct as_feature<tag::mean_of_weights(immediate)>
181{
182    typedef tag::immediate_mean_of_weights type;
183};
184
185// mean_of_variates<VariateType, VariateTag>(lazy) -> mean_of_variates<VariateType, VariateTag>
186template<typename VariateType, typename VariateTag>
187struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(lazy)>
188{
189    typedef tag::mean_of_variates<VariateType, VariateTag> type;
190};
191
192// mean_of_variates<VariateType, VariateTag>(immediate) -> immediate_mean_of_variates<VariateType, VariateTag>
193template<typename VariateType, typename VariateTag>
194struct as_feature<tag::mean_of_variates<VariateType, VariateTag>(immediate)>
195{
196    typedef tag::immediate_mean_of_variates<VariateType, VariateTag> type;
197};
198
199// for the purposes of feature-based dependency resolution,
200// immediate_mean provides the same feature as mean
201template<>
202struct feature_of<tag::immediate_mean>
203  : feature_of<tag::mean>
204{
205};
206
207// for the purposes of feature-based dependency resolution,
208// immediate_mean provides the same feature as mean
209template<>
210struct feature_of<tag::immediate_mean_of_weights>
211  : feature_of<tag::mean_of_weights>
212{
213};
214
215// for the purposes of feature-based dependency resolution,
216// immediate_mean provides the same feature as mean
217template<typename VariateType, typename VariateTag>
218struct feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
219  : feature_of<tag::mean_of_variates<VariateType, VariateTag> >
220{
221};
222
223// So that mean can be automatically substituted with
224// weighted_mean when the weight parameter is non-void.
225template<>
226struct as_weighted_feature<tag::mean>
227{
228    typedef tag::weighted_mean type;
229};
230
231template<>
232struct feature_of<tag::weighted_mean>
233  : feature_of<tag::mean>
234{};
235
236// So that immediate_mean can be automatically substituted with
237// immediate_weighted_mean when the weight parameter is non-void.
238template<>
239struct as_weighted_feature<tag::immediate_mean>
240{
241    typedef tag::immediate_weighted_mean type;
242};
243
244template<>
245struct feature_of<tag::immediate_weighted_mean>
246  : feature_of<tag::immediate_mean>
247{};
248
249// So that mean_of_weights<> can be automatically substituted with
250// weighted_mean_of_variates<> when the weight parameter is non-void.
251template<typename VariateType, typename VariateTag>
252struct as_weighted_feature<tag::mean_of_variates<VariateType, VariateTag> >
253{
254    typedef tag::weighted_mean_of_variates<VariateType, VariateTag> type;
255};
256
257template<typename VariateType, typename VariateTag>
258struct feature_of<tag::weighted_mean_of_variates<VariateType, VariateTag> >
259  : feature_of<tag::mean_of_variates<VariateType, VariateTag> >
260{
261};
262
263// So that immediate_mean_of_weights<> can be automatically substituted with
264// immediate_weighted_mean_of_variates<> when the weight parameter is non-void.
265template<typename VariateType, typename VariateTag>
266struct as_weighted_feature<tag::immediate_mean_of_variates<VariateType, VariateTag> >
267{
268    typedef tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> type;
269};
270
271template<typename VariateType, typename VariateTag>
272struct feature_of<tag::immediate_weighted_mean_of_variates<VariateType, VariateTag> >
273  : feature_of<tag::immediate_mean_of_variates<VariateType, VariateTag> >
274{
275};
276
277////////////////////////////////////////////////////////////////////////////
278//// droppable_accumulator<mean_impl>
279////  need to specialize droppable lazy mean to cache the result at the
280////  point the accumulator is dropped.
281///// INTERNAL ONLY
282/////
283//template<typename Sample, typename SumFeature>
284//struct droppable_accumulator<impl::mean_impl<Sample, SumFeature> >
285//  : droppable_accumulator_base<
286//        with_cached_result<impl::mean_impl<Sample, SumFeature> >
287//    >
288//{
289//    template<typename Args>
290//    droppable_accumulator(Args const &args)
291//      : droppable_accumulator::base(args)
292//    {
293//    }
294//};
295
296}} // namespace boost::accumulators
297
298#endif