My Project
statistics.hh
Go to the documentation of this file.
1/* -*- mia-c++ -*-
2 *
3 * This file is part of MIA - a toolbox for medical image analysis
4 * Copyright (c) Leipzig, Madrid 1999-2017 Gert Wollny
5 *
6 * MIA is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with MIA; if not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20
21#ifndef mia_core_statistics_hh
22#define mia_core_statistics_hh
23
24#include <cmath>
25#include <mia/core/filter.hh>
26
27
29
36struct FMeanVariance: public TFilter< std::pair<double, double>> {
37
43
51 template <typename T>
52 result_type operator()( const T& data) const;
53};
54
60struct FMedianMAD: public TFilter< std::pair<double, double>> {
61
67
74 template <typename T>
75 result_type operator()( const T& data) const;
76private:
77 double median(std::vector<double>& buf)const;
78};
79
80
81
82template <typename T>
84{
85 double sum = 0.0;
86 double sum2 = 0.0;
87 double n = data.size();
88
89 for (auto i = data.begin(); i != data.end(); ++i) {
90 sum += *i;
91 sum2 += *i * *i;
92 }
93
94 FMeanVariance::result_type result = {0.0, 0.0};
95
96 if (n > 0) {
97 result.first = sum / n;
98
99 if (n > 1)
100 result.second = sqrt((sum2 - result.first * sum) / (n - 1));
101 }
102
103 return result;
104}
105
106template <typename T>
108{
109 std::vector<double> buffer(data.size());
110 copy(data.begin(), data.end(), buffer.begin());
112 result.first = median(buffer);
113 transform(buffer.begin(), buffer.end(), buffer.begin(),
114 [&result](double x) {
115 return fabs(x - result.first);
116 });
117 result.second = median(buffer);
118 return result;
119}
120
121double FMedianMAD::median(std::vector<double>& buf)const
122{
123 if (buf.empty())
124 return 0.0;
125
126 if (buf.size() & 1) {
127 auto i = buf.begin() + (buf.size() - 1) / 2;
128 std::nth_element(buf.begin(), i, buf.end());
129 return *i;
130 } else {
131 auto i1 = buf.begin() + buf.size() / 2 - 1;
132 auto i2 = buf.begin() + buf.size() / 2;
133 std::nth_element(buf.begin(), i1, buf.end());
134 std::nth_element(buf.begin(), i2, buf.end());
135 return (*i1 + *i2) / 2.0;
136 }
137}
138
140#endif
#define NS_MIA_BEGIN
conveniance define to start the mia namespace
Definition defines.hh:33
#define NS_MIA_END
conveniance define to end the mia namespace
Definition defines.hh:36
Functor to be called by mia::filter to evaluate mean and variance of a series of data.
Definition statistics.hh:36
TFilter< std::pair< double, double > >::result_type result_type
Definition statistics.hh:42
result_type operator()(const T &data) const
Definition statistics.hh:83
Functor to be called by mia::filter to evaluate median and median average distance (MAD) of a series ...
Definition statistics.hh:60
result_type operator()(const T &data) const
TFilter< std::pair< double, double > >::result_type result_type
Definition statistics.hh:66
base class for all filer type functors.