iRoCS Toolbox  1.1.0
NormalPDF-inl.hh
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22 
23 #ifndef NORMALPDF_INL_HH
24 #define NORMALPDF_INL_HH
25 
26 #ifdef HAVE_CONFIG_H
27 #include <config.hh>
28 #endif
29 
30 #include "NormalPDF.hh"
31 
34 
35 namespace segmentation {
36 
37 // NormalPdf
38 template<typename T>
40  const blitz::Array< T, 2 >& samples
41 ) {
42  atb::BlitzIndexT dim = samples.extent(1);
43  mean_.resize(dim);
44  covariance_.resize(dim, dim);
45  mean_ = 0;
46  covariance_ = 0;
47  blitz::Range all = blitz::Range::all();
48 
49  atb::BlitzIndexT num_samples = samples.extent(0);
50 
51  for (int i = 0; i < num_samples; ++i)
52  // add to mean
53  mean_(all) += samples(i, all);
54 
55  mean_ /= (T)num_samples;
56 
57  for (int i = 0; i < num_samples; ++i) {
58  // estimate covariance
59  blitz::Array<T, 1> sample_demeaned(dim);
60  sample_demeaned = samples(i, all) - mean_;
61  for (int cov_row = 0; cov_row < dim; ++cov_row)
62  for (int cov_col = cov_row; cov_col < dim; ++cov_col) {
63  covariance_(cov_row, cov_col) += sample_demeaned(cov_row) *
64  sample_demeaned(cov_col);
65  // symetric
66  covariance_(cov_col, cov_row) = covariance_(cov_row, cov_col);
67  }
68  }
69  covariance_ /= (T)num_samples;
70 }
71 
72 template<typename T>
74  const blitz::Array<T, 1> &mean,
75  const blitz::Array<T, 2> &information
76 ) : mean_(mean), information_matrix_(information) {
77 }
78 
79 template<typename T>
82 }
83 
84 template<>
86  blitz::Array<double, 2> cov_d(blitz::cast<double>(covariance_));
87  blitz::Array<double, 2> inf_d(covariance_.shape());
88  atb::invert(cov_d, inf_d);
89  information_matrix_.resize(covariance_.shape());
90  information_matrix_ = blitz::cast<float>(inf_d);
91 }
92 
93 
94 
95 template<typename T>
97  const NormalPDF<T>& pdf,
98  const blitz::Array<T, 1>& sample) {
99  blitz::Array<T, 1> sample_demeaned(pdf.mean_.extent(0));
100  sample_demeaned = sample - pdf.mean_;
101  // sample * information matrix
102  blitz::Array<T, 1> sample_inf = atb::mvMult(pdf.information_matrix_,
103  sample_demeaned);
104  // mahalanobis distance
105  T dot_product = (T)atb::dot(sample_inf, sample_demeaned);
106  return std::sqrt(dot_product);
107 }
108 
109 } //namespace
110 
111 #endif // NORMALPDF_INL_HH
blitz::Array< T, 1 > mean_
Definition: NormalPDF.hh:51
T operator()(const NormalPDF< T > &pdf, const blitz::Array< T, 1 > &sample)
void invertCovariance()
Calculates information_matrix_ don&#39;t use information_matrix_ before calling this method.
NormalPDF(const blitz::Array< T, 2 > &samples)
Estimate PDF from given set of samples.
Query specific information about different data types.
Encapsulates a normal pdf.
Definition: NormalPDF.hh:40
void invert(blitz::Array< double, 2 > const &A, blitz::Array< double, 2 > &Ainv)
Compute the inverse of matrix A.
int BlitzIndexT
The native integer type for indexing blitz++ Arrays.
Definition: TypeTraits.hh:56
blitz::TinyVector< BaseT, Dim > mvMult(MatrixT const &m, blitz::TinyVector< BaseT, Dim > const &v)
Quadratic Matrix * Vector product (generic).
blitz::Array< T, 2 > covariance_
Definition: NormalPDF.hh:52
bool all(blitz::TinyMatrix< bool, NRows, NColumns > const &matrix)
all() reduction for boolean blitz::TinyMatrix.
blitz::Array< T, 2 > information_matrix_
Definition: NormalPDF.hh:53
double dot(blitz::Array< DataT, 1 > const &vec1, blitz::Array< DataT, 1 > const &vec2)
Calculation of the inner product (dot product) of the given vectors.