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1 /* |
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2 |
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3 Copyright (C) 1996, 1997 John W. Eaton |
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4 |
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5 This file is part of Octave. |
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6 |
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7 Octave is free software; you can redistribute it and/or modify it |
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8 under the terms of the GNU General Public License as published by the |
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9 Free Software Foundation; either version 2, or (at your option) any |
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10 later version. |
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11 |
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12 Octave is distributed in the hope that it will be useful, but WITHOUT |
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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15 for more details. |
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16 |
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17 You should have received a copy of the GNU General Public License |
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18 along with Octave; see the file COPYING. If not, write to the Free |
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19 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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20 02110-1301, USA. |
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21 |
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22 */ |
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23 |
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24 #ifdef HAVE_CONFIG_H |
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25 #include <config.h> |
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26 #endif |
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27 |
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28 #include "quit.h" |
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29 |
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30 #include "defun-dld.h" |
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31 #include "error.h" |
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32 #include "gripes.h" |
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33 #include "oct-obj.h" |
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34 |
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35 inline double real (double x) { return x; } |
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36 |
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37 template <typename T> |
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38 octave_value_list |
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39 find_nonzero_elem_idx (const T& nda, int nargout) |
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40 { |
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41 octave_value_list retval (((nargout == 0) ? 1 : nargout), Matrix ()); |
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42 |
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43 octave_idx_type count = 0; |
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44 |
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45 octave_idx_type nel = nda.nelem (); |
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46 |
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47 for (octave_idx_type i = 0; i < nel; i++) |
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48 { |
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49 OCTAVE_QUIT; |
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50 |
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51 if (nda(i) != 0.0) |
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52 count++; |
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53 } |
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54 |
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55 // If the original argument was a row vector, force a row vector of |
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56 // the overall indices to be returned. But see below for scalar |
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57 // case... |
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58 |
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59 octave_idx_type result_nr = count; |
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60 octave_idx_type result_nc = 1; |
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61 |
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62 bool scalar_arg = false; |
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63 |
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64 if (nda.ndims () == 2 && nda.rows () == 1) |
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65 { |
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66 result_nr = 1; |
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67 result_nc = count; |
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68 |
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69 scalar_arg = (nda.columns () == 1); |
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70 } |
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71 |
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72 Matrix idx (result_nr, result_nc); |
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73 |
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74 Matrix i_idx (result_nr, result_nc); |
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75 Matrix j_idx (result_nr, result_nc); |
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76 |
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77 T val (dim_vector (result_nr, result_nc)); |
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78 |
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79 if (count > 0) |
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80 { |
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81 count = 0; |
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82 |
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83 octave_idx_type nr = nda.rows (); |
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84 |
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85 octave_idx_type i = 0; |
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86 octave_idx_type j = 0; |
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87 |
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88 for (octave_idx_type k = 0; k < nel; k++) |
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89 { |
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90 OCTAVE_QUIT; |
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91 |
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92 if (nda(k) != 0.0) |
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93 { |
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94 idx(count) = k + 1; |
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95 |
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96 i_idx(count) = i + 1; |
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97 j_idx(count) = j + 1; |
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98 |
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99 val(count) = nda(k); |
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100 |
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101 count++; |
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102 } |
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103 |
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104 i++; |
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105 |
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106 if (i == nr) |
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107 { |
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108 i = 0; |
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109 |
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110 j++; |
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111 } |
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112 } |
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113 } |
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114 else if (scalar_arg) |
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115 { |
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116 idx.resize (0, 0); |
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117 |
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118 i_idx.resize (0, 0); |
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119 j_idx.resize (0, 0); |
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120 |
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121 val.resize (dim_vector (0, 0)); |
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122 } |
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123 |
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124 switch (nargout) |
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125 { |
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126 case 0: |
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127 case 1: |
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128 retval(0) = idx; |
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129 break; |
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130 |
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131 case 3: |
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132 retval(2) = val; |
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133 // Fall through! |
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134 |
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135 case 2: |
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136 retval(1) = j_idx; |
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137 retval(0) = i_idx; |
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138 break; |
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139 |
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140 default: |
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141 panic_impossible (); |
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142 break; |
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143 } |
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144 |
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145 return retval; |
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146 } |
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147 |
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148 template octave_value_list find_nonzero_elem_idx (const NDArray&, int); |
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149 |
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150 template octave_value_list find_nonzero_elem_idx (const ComplexNDArray&, int); |
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151 |
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152 DEFUN_DLD (find, args, nargout, |
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153 "-*- texinfo -*-\n\ |
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154 @deftypefn {Loadable Function} {} find (@var{x})\n\ |
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155 Return a vector of indices of nonzero elements of a matrix. To obtain a\n\ |
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156 single index for each matrix element, Octave pretends that the columns\n\ |
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157 of a matrix form one long vector (like Fortran arrays are stored). For\n\ |
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158 example,\n\ |
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159 \n\ |
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160 @example\n\ |
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161 @group\n\ |
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162 find (eye (2))\n\ |
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163 @result{} [ 1; 4 ]\n\ |
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164 @end group\n\ |
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165 @end example\n\ |
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166 \n\ |
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167 If two outputs are requested, @code{find} returns the row and column\n\ |
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168 indices of nonzero elements of a matrix. For example,\n\ |
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169 \n\ |
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170 @example\n\ |
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171 @group\n\ |
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172 [i, j] = find (2 * eye (2))\n\ |
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173 @result{} i = [ 1; 2 ]\n\ |
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174 @result{} j = [ 1; 2 ]\n\ |
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175 @end group\n\ |
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176 @end example\n\ |
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177 \n\ |
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178 If three outputs are requested, @code{find} also returns a vector\n\ |
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179 containing the nonzero values. For example,\n\ |
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180 \n\ |
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181 @example\n\ |
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182 @group\n\ |
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183 [i, j, v] = find (3 * eye (2))\n\ |
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184 @result{} i = [ 1; 2 ]\n\ |
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185 @result{} j = [ 1; 2 ]\n\ |
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186 @result{} v = [ 3; 3 ]\n\ |
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187 @end group\n\ |
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188 @end example\n\ |
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189 @end deftypefn") |
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190 { |
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191 octave_value_list retval; |
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192 |
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193 int nargin = args.length (); |
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194 |
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195 if (nargin != 1 || nargout > 3) |
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196 { |
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197 print_usage (); |
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198 return retval; |
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199 } |
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200 |
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201 octave_value arg = args(0); |
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202 |
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203 if (arg.is_real_type ()) |
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204 { |
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205 NDArray nda = arg.array_value (); |
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206 |
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207 if (! error_state) |
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208 retval = find_nonzero_elem_idx (nda, nargout); |
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209 } |
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210 else if (arg.is_complex_type ()) |
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211 { |
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212 ComplexNDArray cnda = arg.complex_array_value (); |
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213 |
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214 if (! error_state) |
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215 retval = find_nonzero_elem_idx (cnda, nargout); |
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216 } |
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217 else if (arg.is_string ()) |
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218 { |
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219 charNDArray cnda = arg.char_array_value (); |
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220 |
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221 if (! error_state) |
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222 retval = find_nonzero_elem_idx (cnda, nargout); |
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223 } |
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224 else |
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225 { |
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226 gripe_wrong_type_arg ("find", arg); |
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227 } |
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228 |
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229 return retval; |
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230 } |
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231 |
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232 /* |
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233 ;;; Local Variables: *** |
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234 ;;; mode: C++ *** |
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235 ;;; End: *** |
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236 */ |
