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annotate armadillo-2.4.4/include/armadillo_bits/op_mean_meat.hpp @ 0:8b6102e2a9b0

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Armadillo Library
author maxzanoni76 <max.zanoni@eecs.qmul.ac.uk>
date Wed, 11 Apr 2012 09:27:06 +0100
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rev   line source
max@0 1 // Copyright (C) 2009-2011 NICTA (www.nicta.com.au)
max@0 2 // Copyright (C) 2009-2011 Conrad Sanderson
max@0 3 //
max@0 4 // This file is part of the Armadillo C++ library.
max@0 5 // It is provided without any warranty of fitness
max@0 6 // for any purpose. You can redistribute this file
max@0 7 // and/or modify it under the terms of the GNU
max@0 8 // Lesser General Public License (LGPL) as published
max@0 9 // by the Free Software Foundation, either version 3
max@0 10 // of the License or (at your option) any later version.
max@0 11 // (see http://www.opensource.org/licenses for more info)
max@0 12
max@0 13
max@0 14 //! \addtogroup op_mean
max@0 15 //! @{
max@0 16
max@0 17
max@0 18
max@0 19 template<typename eT>
max@0 20 arma_pure
max@0 21 inline
max@0 22 eT
max@0 23 op_mean::direct_mean(const eT* const X, const uword n_elem)
max@0 24 {
max@0 25 arma_extra_debug_sigprint();
max@0 26
max@0 27 typedef typename get_pod_type<eT>::result T;
max@0 28
max@0 29 const eT result = arrayops::accumulate(X, n_elem) / T(n_elem);
max@0 30
max@0 31 return arma_isfinite(result) ? result : op_mean::direct_mean_robust(X, n_elem);
max@0 32 }
max@0 33
max@0 34
max@0 35
max@0 36 template<typename eT>
max@0 37 inline
max@0 38 eT
max@0 39 op_mean::direct_mean(const Mat<eT>& X, const uword row)
max@0 40 {
max@0 41 arma_extra_debug_sigprint();
max@0 42
max@0 43 typedef typename get_pod_type<eT>::result T;
max@0 44
max@0 45 const uword X_n_cols = X.n_cols;
max@0 46
max@0 47 eT val = eT(0);
max@0 48
max@0 49 for(uword col=0; col<X_n_cols; ++col)
max@0 50 {
max@0 51 val += X.at(row,col);
max@0 52 }
max@0 53
max@0 54 const eT result = val / T(X_n_cols);
max@0 55
max@0 56 return arma_isfinite(result) ? result : direct_mean_robust(X, row);
max@0 57 }
max@0 58
max@0 59
max@0 60
max@0 61 template<typename eT>
max@0 62 inline
max@0 63 eT
max@0 64 op_mean::direct_mean(const subview<eT>& X)
max@0 65 {
max@0 66 arma_extra_debug_sigprint();
max@0 67
max@0 68 typedef typename get_pod_type<eT>::result T;
max@0 69
max@0 70 const uword X_n_elem = X.n_elem;
max@0 71
max@0 72 eT val = eT(0);
max@0 73
max@0 74 for(uword i=0; i<X_n_elem; ++i)
max@0 75 {
max@0 76 val += X[i];
max@0 77 }
max@0 78
max@0 79 const eT result = val / T(X_n_elem);
max@0 80
max@0 81 return arma_isfinite(result) ? result : direct_mean_robust(X);
max@0 82 }
max@0 83
max@0 84
max@0 85
max@0 86 template<typename eT>
max@0 87 inline
max@0 88 eT
max@0 89 op_mean::direct_mean(const diagview<eT>& X)
max@0 90 {
max@0 91 arma_extra_debug_sigprint();
max@0 92
max@0 93 typedef typename get_pod_type<eT>::result T;
max@0 94
max@0 95 const uword X_n_elem = X.n_elem;
max@0 96
max@0 97 eT val = eT(0);
max@0 98
max@0 99 for(uword i=0; i<X_n_elem; ++i)
max@0 100 {
max@0 101 val += X[i];
max@0 102 }
max@0 103
max@0 104 const eT result = val / T(X_n_elem);
max@0 105
max@0 106 return arma_isfinite(result) ? result : direct_mean_robust(X);
max@0 107 }
max@0 108
max@0 109
max@0 110
max@0 111 //! \brief
max@0 112 //! For each row or for each column, find the mean value.
max@0 113 //! The result is stored in a dense matrix that has either one column or one row.
max@0 114 //! The dimension, for which the means are found, is set via the mean() function.
max@0 115 template<typename T1>
max@0 116 inline
max@0 117 void
max@0 118 op_mean::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_mean>& in)
max@0 119 {
max@0 120 arma_extra_debug_sigprint();
max@0 121
max@0 122 typedef typename T1::elem_type eT;
max@0 123 typedef typename get_pod_type<eT>::result T;
max@0 124
max@0 125 const unwrap_check<T1> tmp(in.m, out);
max@0 126 const Mat<eT>& X = tmp.M;
max@0 127
max@0 128 const uword dim = in.aux_uword_a;
max@0 129 arma_debug_check( (dim > 1), "mean(): incorrect usage. dim must be 0 or 1");
max@0 130
max@0 131 const uword X_n_rows = X.n_rows;
max@0 132 const uword X_n_cols = X.n_cols;
max@0 133
max@0 134 if(dim == 0)
max@0 135 {
max@0 136 arma_extra_debug_print("op_mean::apply(), dim = 0");
max@0 137
max@0 138 out.set_size( (X_n_rows > 0) ? 1 : 0, X_n_cols );
max@0 139
max@0 140 if(X_n_rows > 0)
max@0 141 {
max@0 142 eT* out_mem = out.memptr();
max@0 143
max@0 144 for(uword col=0; col<X_n_cols; ++col)
max@0 145 {
max@0 146 out_mem[col] = op_mean::direct_mean( X.colptr(col), X_n_rows );
max@0 147 }
max@0 148 }
max@0 149 }
max@0 150 else
max@0 151 if(dim == 1)
max@0 152 {
max@0 153 arma_extra_debug_print("op_mean::apply(), dim = 1");
max@0 154
max@0 155 out.set_size(X_n_rows, (X_n_cols > 0) ? 1 : 0);
max@0 156
max@0 157 if(X_n_cols > 0)
max@0 158 {
max@0 159 eT* out_mem = out.memptr();
max@0 160
max@0 161 for(uword row=0; row<X_n_rows; ++row)
max@0 162 {
max@0 163 out_mem[row] = op_mean::direct_mean( X, row );
max@0 164 }
max@0 165 }
max@0 166 }
max@0 167 }
max@0 168
max@0 169
max@0 170
max@0 171 template<typename eT>
max@0 172 arma_pure
max@0 173 inline
max@0 174 eT
max@0 175 op_mean::direct_mean_robust(const eT* const X, const uword n_elem)
max@0 176 {
max@0 177 arma_extra_debug_sigprint();
max@0 178
max@0 179 // use an adapted form of the mean finding algorithm from the running_stat class
max@0 180
max@0 181 typedef typename get_pod_type<eT>::result T;
max@0 182
max@0 183 uword i,j;
max@0 184
max@0 185 eT r_mean = eT(0);
max@0 186
max@0 187 for(i=0, j=1; j<n_elem; i+=2, j+=2)
max@0 188 {
max@0 189 const eT Xi = X[i];
max@0 190 const eT Xj = X[j];
max@0 191
max@0 192 r_mean = r_mean + (Xi - r_mean)/T(j); // we need i+1, and j is equivalent to i+1 here
max@0 193 r_mean = r_mean + (Xj - r_mean)/T(j+1);
max@0 194 }
max@0 195
max@0 196
max@0 197 if(i < n_elem)
max@0 198 {
max@0 199 const eT Xi = X[i];
max@0 200
max@0 201 r_mean = r_mean + (Xi - r_mean)/T(i+1);
max@0 202 }
max@0 203
max@0 204 return r_mean;
max@0 205 }
max@0 206
max@0 207
max@0 208
max@0 209 template<typename eT>
max@0 210 inline
max@0 211 eT
max@0 212 op_mean::direct_mean_robust(const Mat<eT>& X, const uword row)
max@0 213 {
max@0 214 arma_extra_debug_sigprint();
max@0 215
max@0 216 typedef typename get_pod_type<eT>::result T;
max@0 217
max@0 218 const uword X_n_cols = X.n_cols;
max@0 219
max@0 220 eT r_mean = eT(0);
max@0 221
max@0 222 for(uword col=0; col<X_n_cols; ++col)
max@0 223 {
max@0 224 r_mean = r_mean + (X.at(row,col) - r_mean)/T(col+1);
max@0 225 }
max@0 226
max@0 227 return r_mean;
max@0 228 }
max@0 229
max@0 230
max@0 231
max@0 232 template<typename eT>
max@0 233 inline
max@0 234 eT
max@0 235 op_mean::direct_mean_robust(const subview<eT>& X)
max@0 236 {
max@0 237 arma_extra_debug_sigprint();
max@0 238
max@0 239 typedef typename get_pod_type<eT>::result T;
max@0 240
max@0 241 const uword X_n_elem = X.n_elem;
max@0 242
max@0 243 eT r_mean = eT(0);
max@0 244
max@0 245 for(uword i=0; i<X_n_elem; ++i)
max@0 246 {
max@0 247 r_mean = r_mean + (X[i] - r_mean)/T(i+1);
max@0 248 }
max@0 249
max@0 250 return r_mean;
max@0 251 }
max@0 252
max@0 253
max@0 254
max@0 255 template<typename eT>
max@0 256 inline
max@0 257 eT
max@0 258 op_mean::direct_mean_robust(const diagview<eT>& X)
max@0 259 {
max@0 260 arma_extra_debug_sigprint();
max@0 261
max@0 262 typedef typename get_pod_type<eT>::result T;
max@0 263
max@0 264 const uword X_n_elem = X.n_elem;
max@0 265
max@0 266 eT r_mean = eT(0);
max@0 267
max@0 268 for(uword i=0; i<X_n_elem; ++i)
max@0 269 {
max@0 270 r_mean = r_mean + (X[i] - r_mean)/T(i+1);
max@0 271 }
max@0 272
max@0 273 return r_mean;
max@0 274 }
max@0 275
max@0 276
max@0 277
max@0 278 //! @}
max@0 279