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1 ## Copyright (C) 1996 Kurt Hornik |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## usage: findstr (s, t [, overlap]) |
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21 ## |
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22 ## Returns the vector of all positions in the longer of the two strings |
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23 ## S and T where an occurence of the shorter of the two starts. |
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24 ## |
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25 ## If the optional argument OVERLAP is nonzero, the returned vector |
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26 ## can include overlapping positions (this is the default). |
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27 ## |
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28 ## For example, |
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29 ## |
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30 ## findstr ("abababa", "aba") => [1, 3, 5] |
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31 ## findstr ("abababa", "aba", 0) => [1, 5] |
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32 |
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33 ## Author: jwe |
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34 |
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35 function v = findstr (s, t, overlap) |
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36 |
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37 ## Original version by Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>. |
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38 |
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39 if (nargin < 2 || nargin > 3) |
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40 usage ("findstr (s, t [, overlap])"); |
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41 endif |
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42 |
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43 if (nargin == 2) |
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44 overlap = 1; |
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45 endif |
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46 |
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47 if (isstr (s) && isstr (t)) |
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48 |
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49 ## Make S be the longer string. |
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50 |
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51 if (length (s) < length (t)) |
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52 tmp = s; |
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53 s = t; |
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54 t = tmp; |
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55 endif |
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56 |
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57 s = toascii (s); |
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58 t = toascii (t); |
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59 |
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60 l_t = length (t); |
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61 |
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62 ind = 1 : l_t; |
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63 limit = length (s) - l_t + 1; |
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64 v = zeros (1, limit); |
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65 i = 0; |
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66 |
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67 k = 1; |
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68 while (k <= limit) |
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69 if (s (ind + k - 1) == t) |
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70 v (++i) = k; |
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71 if (! overlap) |
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72 k = k + l_t - 1; |
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73 endif |
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74 endif |
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75 k++; |
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76 endwhile |
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77 |
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78 if (i > 0) |
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79 v = v (1:i); |
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80 else |
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81 v = []; |
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82 endif |
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83 |
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84 else |
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85 error ("findstr: expecting first two arguments to be strings"); |
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86 endif |
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87 |
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88 endfunction |
