comparison DEPENDENCIES/generic/include/boost/accumulators/statistics/density.hpp @ 16:2665513ce2d3

Add boost headers

+
+///////////////////////////////////////////////////////////////////////////////
+// density.hpp
+//
+//  Copyright 2006 Daniel Egloff, 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_DENSITY_HPP_DE_01_01_2006
+#define BOOST_ACCUMULATORS_STATISTICS_DENSITY_HPP_DE_01_01_2006
+
+#include <vector>
+#include <limits>
+#include <functional>
+#include <boost/range.hpp>
+#include <boost/parameter/keyword.hpp>
+#include <boost/mpl/placeholders.hpp>
+#include <boost/accumulators/accumulators_fwd.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/max.hpp>
+#include <boost/accumulators/statistics/min.hpp>
+
+namespace boost { namespace accumulators
+{
+
+///////////////////////////////////////////////////////////////////////////////
+// cache_size and num_bins named parameters
+//
+BOOST_PARAMETER_NESTED_KEYWORD(tag, density_cache_size, cache_size)
+BOOST_PARAMETER_NESTED_KEYWORD(tag, density_num_bins, num_bins)
+
+BOOST_ACCUMULATORS_IGNORE_GLOBAL(density_cache_size)
+BOOST_ACCUMULATORS_IGNORE_GLOBAL(density_num_bins)
+
+namespace impl
+{
+    ///////////////////////////////////////////////////////////////////////////////
+    // density_impl
+    //  density histogram
+    /**
+        @brief Histogram density estimator
+
+        The histogram density estimator returns a histogram of the sample distribution. The positions and sizes of the bins
+        are determined using a specifiable number of cached samples (cache_size). The range between the minimum and the
+        maximum of the cached samples is subdivided into a specifiable number of bins (num_bins) of same size. Additionally,
+        an under- and an overflow bin is added to capture future under- and overflow samples. Once the bins are determined,
+        the cached samples and all subsequent samples are added to the correct bins. At the end, a range of std::pair is
+        return, where each pair contains the position of the bin (lower bound) and the samples count (normalized with the
+        total number of samples).
+
+        @param  density_cache_size Number of first samples used to determine min and max.
+        @param  density_num_bins Number of bins (two additional bins collect under- and overflow samples).
+    */
+    template<typename Sample>
+    struct density_impl
+      : accumulator_base
+    {
+        typedef typename numeric::functional::fdiv<Sample, std::size_t>::result_type float_type;
+        typedef std::vector<std::pair<float_type, float_type> > histogram_type;
+        typedef std::vector<float_type> array_type;
+        // for boost::result_of
+        typedef iterator_range<typename histogram_type::iterator> result_type;
+
+        template<typename Args>
+        density_impl(Args const &args)
+            : cache_size(args[density_cache_size])
+            , cache(cache_size)
+            , num_bins(args[density_num_bins])
+            , samples_in_bin(num_bins + 2, 0.)
+            , bin_positions(num_bins + 2)
+            , histogram(
+                num_bins + 2
+              , std::make_pair(
+                    numeric::fdiv(args[sample | Sample()],(std::size_t)1)
+                  , numeric::fdiv(args[sample | Sample()],(std::size_t)1)
+                )
+              )
+            , is_dirty(true)
+        {
+        }
+
+        template<typename Args>
+        void operator ()(Args const &args)
+        {
+            this->is_dirty = true;
+
+            std::size_t cnt = count(args);
+
+            // Fill up cache with cache_size first samples
+            if (cnt <= this->cache_size)
+            {
+                this->cache[cnt - 1] = args[sample];
+            }
+
+            // Once cache_size samples have been accumulated, create num_bins bins of same size between
+            // the minimum and maximum of the cached samples as well as under and overflow bins.
+            // Store their lower bounds (bin_positions) and fill the bins with the cached samples (samples_in_bin).
+            if (cnt == this->cache_size)
+            {
+                float_type minimum = numeric::fdiv((min)(args), (std::size_t)1);
+                float_type maximum = numeric::fdiv((max)(args), (std::size_t)1);
+                float_type bin_size = numeric::fdiv(maximum - minimum, this->num_bins );
+
+                // determine bin positions (their lower bounds)
+                for (std::size_t i = 0; i < this->num_bins + 2; ++i)
+                {
+                    this->bin_positions[i] = minimum + (i - 1.) * bin_size;
+                }
+
+                for (typename array_type::const_iterator iter = this->cache.begin(); iter != this->cache.end(); ++iter)
+                {
+                    if (*iter < this->bin_positions[1])
+                    {
+                        ++(this->samples_in_bin[0]);
+                    }
+                    else if (*iter >= this->bin_positions[this->num_bins + 1])
+                    {
+                        ++(this->samples_in_bin[this->num_bins + 1]);
+                    }
+                    else
+                    {
+                        typename array_type::iterator it = std::upper_bound(
+                            this->bin_positions.begin()
+                          , this->bin_positions.end()
+                          , *iter
+                        );
+
+                        std::size_t d = std::distance(this->bin_positions.begin(), it);
+                        ++(this->samples_in_bin[d - 1]);
+                    }
+                }
+            }
+            // Add each subsequent sample to the correct bin
+            else if (cnt > this->cache_size)
+            {
+                if (args[sample] < this->bin_positions[1])
+                {
+                    ++(this->samples_in_bin[0]);
+                }
+                else if (args[sample] >= this->bin_positions[this->num_bins + 1])
+                {
+                    ++(this->samples_in_bin[this->num_bins + 1]);
+                }
+                else
+                {
+                    typename array_type::iterator it = std::upper_bound(
+                        this->bin_positions.begin()
+                      , this->bin_positions.end()
+                      , args[sample]
+                    );
+
+                    std::size_t d = std::distance(this->bin_positions.begin(), it);
+                    ++(this->samples_in_bin[d - 1]);
+                }
+            }
+        }
+
+        /**
+            @pre The number of samples must meet or exceed the cache size
+        */
+        template<typename Args>
+        result_type result(Args const &args) const
+        {
+            if (this->is_dirty)
+            {
+                this->is_dirty = false;
+
+                // creates a vector of std::pair where each pair i holds
+                // the values bin_positions[i] (x-axis of histogram) and
+                // samples_in_bin[i] / cnt (y-axis of histogram).
+
+                for (std::size_t i = 0; i < this->num_bins + 2; ++i)
+                {
+                    this->histogram[i] = std::make_pair(this->bin_positions[i], numeric::fdiv(this->samples_in_bin[i], count(args)));
+                }
+            }
+            // returns a range of pairs
+            return make_iterator_range(this->histogram);
+        }
+
+    private:
+        std::size_t            cache_size;      // number of cached samples
+        array_type             cache;           // cache to store the first cache_size samples
+        std::size_t            num_bins;        // number of bins
+        array_type             samples_in_bin;  // number of samples in each bin
+        array_type             bin_positions;   // lower bounds of bins
+        mutable histogram_type histogram;       // histogram
+        mutable bool is_dirty;
+    };
+
+} // namespace impl
+
+///////////////////////////////////////////////////////////////////////////////
+// tag::density
+//
+namespace tag
+{
+    struct density
+      : depends_on<count, min, max>
+      , density_cache_size
+      , density_num_bins
+    {
+        /// INTERNAL ONLY
+        ///
+        typedef accumulators::impl::density_impl<mpl::_1> impl;
+
+        #ifdef BOOST_ACCUMULATORS_DOXYGEN_INVOKED
+        /// tag::density::cache_size named parameter
+        /// tag::density::num_bins named parameter
+        static boost::parameter::keyword<density_cache_size> const cache_size;
+        static boost::parameter::keyword<density_num_bins> const num_bins;
+        #endif
+    };
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// extract::density
+//
+namespace extract
+{
+    extractor<tag::density> const density = {};
+
+    BOOST_ACCUMULATORS_IGNORE_GLOBAL(density)
+}
+
+using extract::density;
+
+// So that density can be automatically substituted
+// with weighted_density when the weight parameter is non-void.
+template<>
+struct as_weighted_feature<tag::density>
+{
+    typedef tag::weighted_density type;
+};
+
+template<>
+struct feature_of<tag::weighted_density>
+  : feature_of<tag::density>
+{
+};
+
+}} // namespace boost::accumulators
+
+#endif