/usr/include/boost/accumulators/statistics
Edit: /usr/include/boost/accumulators/statistics/density.hpp (10007B)
///////////////////////////////////////////////////////////////////////////////
// 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
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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
struct density_impl
: accumulator_base
{
typedef typename numeric::functional::fdiv::result_type float_type;
typedef std::vector > histogram_type;
typedef std::vector array_type;
// for boost::result_of
typedef iterator_range result_type;
template
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
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
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);
}
// make this accumulator serializeable
// TODO split to save/load and check on parameters provided in ctor
template
void serialize(Archive & ar, const unsigned int file_version)
{
ar & cache_size;
ar & cache;
ar & num_bins;
ar & samples_in_bin;
ar & bin_positions;
ar & histogram;
ar & is_dirty;
}
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
, density_cache_size
, density_num_bins
{
/// INTERNAL ONLY
///
typedef accumulators::impl::density_impl impl;
#ifdef BOOST_ACCUMULATORS_DOXYGEN_INVOKED
/// tag::density::cache_size named parameter
/// tag::density::num_bins named parameter
static boost::parameter::keyword const cache_size;
static boost::parameter::keyword const num_bins;
#endif
};
}
///////////////////////////////////////////////////////////////////////////////
// extract::density
//
namespace extract
{
extractor 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
{
typedef tag::weighted_density type;
};
template<>
struct feature_of
: feature_of
{
};
}} // namespace boost::accumulators
#endif