statistics.hh
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/* -*- mia-c++ -*-
*
* This file is part of MIA - a toolbox for medical image analysis
* Copyright (c) Leipzig, Madrid 1999-2017 Gert Wollny
*
* MIA is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MIA; if not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef mia_core_statistics_hh
#define mia_core_statistics_hh
#include <cmath>
#include <mia/core/filter.hh>
NS_MIA_BEGIN
struct FMeanVariance: public TFilter< std::pair<double, double>> {
typedef TFilter< std::pair<double, double>>::result_type result_type;
template <typename T>
result_type operator()( const T& data) const;
};
struct FMedianMAD: public TFilter< std::pair<double, double>> {
typedef TFilter< std::pair<double, double>>::result_type result_type;
template <typename T>
result_type operator()( const T& data) const;
private:
double median(std::vector<double>& buf)const;
};
template <typename T>
FMeanVariance::result_type FMeanVariance::operator()( const T& data) const
{
double sum = 0.0;
double sum2 = 0.0;
double n = data.size();
for (auto i = data.begin(); i != data.end(); ++i) {
sum += *i;
sum2 += *i * *i;
}
FMeanVariance::result_type result = {0.0, 0.0};
if (n > 0) {
result.first = sum / n;
if (n > 1)
result.second = sqrt((sum2 - result.first * sum) / (n - 1));
}
return result;
}
template <typename T>
FMedianMAD::result_type FMedianMAD::operator()( const T& data) const
{
std::vector<double> buffer(data.size());
copy(data.begin(), data.end(), buffer.begin());
FMedianMAD::result_type result;
result.first = median(buffer);
transform(buffer.begin(), buffer.end(), buffer.begin(),
[&result](double x) {
return fabs(x - result.first);
});
result.second = median(buffer);
return result;
}
double FMedianMAD::median(std::vector<double>& buf)const
{
if (buf.empty())
return 0.0;
if (buf.size() & 1) {
auto i = buf.begin() + (buf.size() - 1) / 2;
std::nth_element(buf.begin(), i, buf.end());
return *i;
} else {
auto i1 = buf.begin() + buf.size() / 2 - 1;
auto i2 = buf.begin() + buf.size() / 2;
std::nth_element(buf.begin(), i1, buf.end());
std::nth_element(buf.begin(), i2, buf.end());
return (*i1 + *i2) / 2.0;
}
}
NS_MIA_END
#endif
filter.hh
NS_MIA_BEGIN
#define NS_MIA_BEGIN
conveniance define to start the mia namespace
Definition defines.hh:33
NS_MIA_END
#define NS_MIA_END
conveniance define to end the mia namespace
Definition defines.hh:36
FMeanVariance
Functor to be called by mia::filter to evaluate mean and variance of a series of data.
Definition statistics.hh:36
FMeanVariance::result_type
TFilter< std::pair< double, double > >::result_type result_type
Definition statistics.hh:42
FMeanVariance::operator()
result_type operator()(const T &data) const
Definition statistics.hh:83
FMedianMAD
Functor to be called by mia::filter to evaluate median and median average distance (MAD) of a series ...
Definition statistics.hh:60
FMedianMAD::operator()
result_type operator()(const T &data) const
Definition statistics.hh:107
FMedianMAD::result_type
TFilter< std::pair< double, double > >::result_type result_type
Definition statistics.hh:66
TFilter
base class for all filer type functors.
Definition core/filter.hh:70