|
6139
|
1 ## Copyright (C) 1996, 2006 Kurt Hornik |
|
2325
|
2 ## |
|
2313
|
3 ## This file is part of Octave. |
|
|
4 ## |
|
|
5 ## Octave is free software; you can redistribute it and/or modify it |
|
|
6 ## under the terms of the GNU General Public License as published by |
|
7016
|
7 ## the Free Software Foundation; either version 3 of the License, or (at |
|
|
8 ## your option) any later version. |
|
2313
|
9 ## |
|
|
10 ## Octave is distributed in the hope that it will be useful, but |
|
|
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
|
|
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
|
13 ## General Public License for more details. |
|
|
14 ## |
|
|
15 ## You should have received a copy of the GNU General Public License |
|
7016
|
16 ## along with Octave; see the file COPYING. If not, see |
|
|
17 ## <http://www.gnu.org/licenses/>. |
|
2271
|
18 |
|
3361
|
19 ## -*- texinfo -*- |
|
|
20 ## @deftypefn {Function File} {} index (@var{s}, @var{t}) |
|
6139
|
21 ## @deftypefnx {Function File} {} index (@var{s}, @var{t}, @var{direction}) |
|
3361
|
22 ## Return the position of the first occurrence of the string @var{t} in the |
|
|
23 ## string @var{s}, or 0 if no occurrence is found. For example, |
|
3426
|
24 ## |
|
3361
|
25 ## @example |
|
|
26 ## index ("Teststring", "t") |
|
|
27 ## @result{} 4 |
|
|
28 ## @end example |
|
3426
|
29 ## |
|
6139
|
30 ## If @var{direction} is @samp{"first"}, return the first element found. |
|
|
31 ## If @var{direction} is @samp{"last"}, return the last element found. |
|
|
32 ## The @code{rindex} function is equivalent to @code{index} with |
|
|
33 ## @var{direction} set to @samp{"last"}. |
|
|
34 ## |
|
|
35 ## @strong{Caution:} This function does not work for arrays of |
|
|
36 ## character strings. |
|
|
37 ## @seealso{find, rindex} |
|
3361
|
38 ## @end deftypefn |
|
2271
|
39 |
|
5428
|
40 ## Author: Kurt Hornik <Kurt.Hornik@wu-wien.ac.at> |
|
2355
|
41 ## Adapted-By: jwe |
|
2314
|
42 |
|
6139
|
43 function n = index (s, t, direction) |
|
2271
|
44 |
|
2303
|
45 ## This is patterned after the AWK function of the same name. |
|
2271
|
46 |
|
6139
|
47 if (nargin < 2 || nargin > 3) |
|
6046
|
48 print_usage (); |
|
6139
|
49 elseif (nargin < 3) |
|
|
50 direction = "first"; |
|
2271
|
51 endif |
|
6139
|
52 direction = lower (direction); |
|
|
53 |
|
6749
|
54 if (! (ischar (s) && ischar (t))) |
|
6139
|
55 error ("index: expecting character string arguments"); |
|
|
56 elseif (! strcmp (direction, {"first", "last"})) |
|
|
57 error ("index: direction must be either \"first\" or \"last\""); |
|
2271
|
58 endif |
|
2325
|
59 |
|
3911
|
60 l_s = length (s); |
|
|
61 l_t = length (t); |
|
6139
|
62 |
|
|
63 n = 0; |
|
|
64 if (l_s == 0 || l_s < l_t) |
|
3911
|
65 ## zero length source, or target longer than source |
|
6139
|
66 ## return 0 |
|
3911
|
67 v = []; |
|
6139
|
68 |
|
|
69 elseif (l_t == 0) |
|
3911
|
70 ## zero length target: return first |
|
|
71 v = 1; |
|
6139
|
72 |
|
|
73 elseif (l_t == 1) |
|
3911
|
74 ## length one target: simple find |
|
6139
|
75 v = find (s==t, 1, direction); |
|
|
76 |
|
|
77 elseif (l_t == 2) |
|
3911
|
78 ## length two target: find first at i and second at i+1 |
|
6139
|
79 v = find (s (1:l_s-1) == t(1) & s(2:l_s) == t(2), 1, direction); |
|
|
80 |
|
3911
|
81 else |
|
|
82 ## length three or more: match the first three by find then go through |
|
|
83 ## the much smaller list to determine which of them are real matches |
|
|
84 limit = l_s - l_t + 1; |
|
6139
|
85 v = find (s (1:limit) == t(1) |
|
|
86 & s (2:limit+1) == t(2) |
|
|
87 & s (3:limit+2) == t(3)); |
|
|
88 if (strcmp (direction, "last")) |
|
|
89 v = v(length(v):-1:1); |
|
3911
|
90 endif |
|
6139
|
91 |
|
|
92 if (l_t > 3) |
|
|
93 |
|
|
94 ## force strings to be both row vectors or both column vectors |
|
|
95 if (all (size (s) != size (t))) |
|
|
96 t = t.'; |
|
3911
|
97 endif |
|
|
98 |
|
6139
|
99 ## search index vector for a match |
|
|
100 ind = 0:l_t-1; |
|
|
101 ## return 0 if loop terminates without finding any match |
|
|
102 for idx = 1:length(v) |
|
|
103 if (s (v(idx) + ind) == t) |
|
|
104 n = v(idx); |
|
|
105 break; |
|
|
106 endif |
|
|
107 endfor |
|
6901
|
108 v = []; |
|
6139
|
109 endif |
|
3911
|
110 |
|
|
111 endif |
|
|
112 |
|
6139
|
113 if (n == 0 && ! isempty (v)) |
|
|
114 ## return the first found if n is not already set and v is not empty |
|
|
115 n = v(1); |
|
|
116 endif |
|
|
117 |
|
2271
|
118 endfunction |
|
6139
|
119 |
|
|
120 ## Test the function out |
|
|
121 %!assert(index("astringbstringcstring", "s"), 2) |
|
|
122 %!assert(index("astringbstringcstring", "st"), 2) |
|
|
123 %!assert(index("astringbstringcstring", "str"), 2) |
|
|
124 %!assert(index("astringbstringcstring", "string"), 2) |
|
6901
|
125 %!assert(index("abc---", "abc+++"), 0) |
|
6139
|
126 |
|
|
127 ## test everything out in reverse |
|
|
128 %!assert(index("astringbstringcstring", "s", "last"), 16) |
|
|
129 %!assert(index("astringbstringcstring", "st", "last"), 16) |
|
|
130 %!assert(index("astringbstringcstring", "str", "last"), 16) |
|
|
131 %!assert(index("astringbstringcstring", "string", "last"), 16) |
|
6901
|
132 %!assert(index("abc---", "abc+++", "last"), 0) |
