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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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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20 |
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21 */ |
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22 |
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23 #ifdef HAVE_CONFIG_H |
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24 #include <config.h> |
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25 #endif |
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26 |
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27 #include "defun-dld.h" |
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28 #include "error.h" |
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29 #include "gripes.h" |
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30 #include "oct-obj.h" |
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31 |
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32 #define DO_FIND_OP(T) \ |
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33 do \ |
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34 { \ |
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35 T tmp (count); \ |
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36 \ |
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37 for (int i = 0; i < count; i++) \ |
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38 tmp (i) = nr * (j_idx (i) - 1.0) + i_idx (i); \ |
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39 \ |
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40 retval(0) = tmp; \ |
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41 } \ |
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42 while (0) |
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43 |
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44 |
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45 static octave_value_list |
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46 find_to_fortran_idx (const ColumnVector i_idx, const ColumnVector j_idx, |
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47 const octave_value& val, int nr, int nargout) |
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48 { |
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49 octave_value_list retval; |
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50 |
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51 switch (nargout) |
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52 { |
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53 case 0: |
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54 case 1: |
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55 { |
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56 // If the original argument was a row vector, force a row |
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57 // vector of indices to be returned. |
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58 |
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59 int count = i_idx.length (); |
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60 |
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61 if (nr == 1) |
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62 DO_FIND_OP(RowVector); |
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63 else |
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64 DO_FIND_OP(ColumnVector); |
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65 } |
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66 break; |
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67 |
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68 case 3: |
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69 retval(2) = val; |
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70 // Fall through! |
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71 |
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72 case 2: |
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73 retval(1) = j_idx; |
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74 retval(0) = i_idx; |
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75 break; |
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76 |
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77 default: |
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78 panic_impossible (); |
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79 break; |
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80 } |
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81 |
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82 return retval; |
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83 } |
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84 |
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85 static octave_value_list |
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86 find_nonzero_elem_idx (const Matrix& m, int nargout) |
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87 { |
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88 int count = 0; |
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89 int m_nr = m.rows (); |
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90 int m_nc = m.columns (); |
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91 |
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92 int i, j; |
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93 for (j = 0; j < m_nc; j++) |
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94 for (i = 0; i < m_nr; i++) |
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95 if (m (i, j) != 0.0) |
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96 count++; |
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97 |
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98 octave_value_list retval (((nargout == 0) ? 1 : nargout), Matrix ()); |
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99 |
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100 if (count == 0) |
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101 return retval; |
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102 |
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103 ColumnVector i_idx (count); |
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104 ColumnVector j_idx (count); |
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105 ColumnVector v (count); |
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106 |
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107 count = 0; |
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108 for (j = 0; j < m_nc; j++) |
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109 for (i = 0; i < m_nr; i++) |
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110 { |
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111 double d = m (i, j); |
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112 if (d != 0.0) |
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113 { |
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114 i_idx (count) = i + 1; |
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115 j_idx (count) = j + 1; |
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116 v (count) = d; |
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117 count++; |
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118 } |
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119 } |
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120 |
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121 return find_to_fortran_idx (i_idx, j_idx, octave_value (v), m_nr, nargout); |
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122 } |
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123 |
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124 static octave_value_list |
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125 find_nonzero_elem_idx (const ComplexMatrix& m, int nargout) |
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126 { |
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127 int count = 0; |
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128 int m_nr = m.rows (); |
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129 int m_nc = m.columns (); |
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130 |
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131 int i, j; |
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132 for (j = 0; j < m_nc; j++) |
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133 for (i = 0; i < m_nr; i++) |
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134 if (m (i, j) != 0.0) |
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135 count++; |
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136 |
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137 octave_value_list retval (((nargout == 0) ? 1 : nargout), Matrix ()); |
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138 |
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139 if (count == 0) |
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140 return retval; |
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141 |
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142 ColumnVector i_idx (count); |
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143 ColumnVector j_idx (count); |
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144 ComplexColumnVector v (count); |
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145 |
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146 count = 0; |
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147 for (j = 0; j < m_nc; j++) |
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148 for (i = 0; i < m_nr; i++) |
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149 { |
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150 Complex c = m (i, j); |
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151 if (c != 0.0) |
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152 { |
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153 i_idx (count) = i + 1; |
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154 j_idx (count) = j + 1; |
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155 v (count) = c; |
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156 count++; |
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157 } |
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158 } |
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159 |
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160 return find_to_fortran_idx (i_idx, j_idx, octave_value (v), m_nr, nargout); |
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161 } |
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162 |
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163 DEFUN_DLD (find, args, nargout, |
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164 "-*- texinfo -*-\n\ |
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165 @deftypefn {Loadable Function} {} find (@var{x})\n\ |
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166 Return a vector of indices of nonzero elements of a matrix. To obtain a\n\ |
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167 single index for each matrix element, Octave pretends that the columns\n\ |
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168 of a matrix form one long vector (like Fortran arrays are stored). For\n\ |
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169 example,\n\ |
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170 \n\ |
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171 @example\n\ |
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172 @group\n\ |
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173 find (eye (2))\n\ |
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174 @result{} [ 1; 4 ]\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 two outputs are requested, @code{find} returns the row and column\n\ |
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179 indices of nonzero elements of a matrix. 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] = find (2 * 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 @end group\n\ |
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187 @end example\n\ |
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188 \n\ |
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189 If three outputs are requested, @code{find} also returns a vector\n\ |
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190 containing the nonzero values. For example,\n\ |
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191 \n\ |
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192 @example\n\ |
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193 @group\n\ |
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194 [i, j, v] = find (3 * eye (2))\n\ |
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195 @result{} i = [ 1; 2 ]\n\ |
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196 @result{} j = [ 1; 2 ]\n\ |
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197 @result{} v = [ 3; 3 ]\n\ |
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198 @end group\n\ |
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199 @end example\n\ |
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200 @end deftypefn") |
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201 { |
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202 octave_value_list retval; |
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203 |
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204 int nargin = args.length (); |
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205 |
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206 if (nargin != 1 || nargout > 3) |
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207 { |
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208 print_usage ("find"); |
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209 return retval; |
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210 } |
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211 |
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212 octave_value arg = args(0); |
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213 |
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214 if (arg.is_real_type ()) |
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215 { |
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216 Matrix m = arg.matrix_value (); |
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217 |
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218 if (! error_state) |
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219 retval = find_nonzero_elem_idx (m, nargout); |
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220 } |
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221 else if (arg.is_complex_type ()) |
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222 { |
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223 ComplexMatrix m = arg.complex_matrix_value (); |
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224 |
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225 if (! error_state) |
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226 retval = find_nonzero_elem_idx (m, nargout); |
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227 } |
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228 else |
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229 { |
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230 gripe_wrong_type_arg ("find", arg); |
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231 } |
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232 |
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233 return retval; |
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234 } |
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235 |
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236 /* |
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237 ;;; Local Variables: *** |
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238 ;;; mode: C++ *** |
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239 ;;; End: *** |
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240 */ |
