Mercurial > forge

comparison FIXES/index.m @ 0:6b33357c7561 octave-forge

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Initial revision
author pkienzle
date Wed, 10 Oct 2001 19:54:49 +0000
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:6b33357c7561
1 ## Copyright (C) 1996 Kurt Hornik
2 ##
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
7 ## the Free Software Foundation; either version 2, or (at your option)
8 ## any later version.
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
16 ## along with Octave; see the file COPYING. If not, write to the Free
17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
18 ## 02111-1307, USA.
19
20 ## -*- texinfo -*-
21 ## @deftypefn {Function File} {} index (@var{s}, @var{t})
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,
24 ##
25 ## @example
26 ## index ("Teststring", "t")
27 ## @result{} 4
28 ## @end example
29 ##
30 ## @strong{Note:} This function does not work for arrays of strings.
31 ## @end deftypefn
32
33 ## Author: Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>
34 ## Adapted-By: jwe
35 ## Paul Kienzle <pkienzle@kienzle.powernet.co.uk>
36 ## vectorize for speed
37
38 function n = index (s, t)
39
40 ## This is patterned after the AWK function of the same name.
41
42 if (nargin != 2)
43 usage ("index (s, t)");
44 endif
45
46 if (!isstr (s) || !isstr (t) || all (size (s) > 1) || all (size (t) > 1) )
47 error ("index: expecting string arguments");
48 endif
49
50 l_s = length (s);
51 l_t = length (t);
52
53 if ( l_s == 0 || l_s < l_t )
54 ## zero length source, or target longer than source
55 v = [];
56
57 elseif ( l_t == 0 )
58 ## zero length target: return first
59 v = 1;
60
61 elseif ( l_t == 1 )
62 ## length one target: simple find
63 v = find (s==t);
64
65 elseif ( l_t == 2 )
66 ## length two target: find first at i and second at i+1
67 v = find (s (1 : l_s-1) == t (1) & s (2 : l_s) == t (2));
68
69 else
70 ## length three or more: match the first three by find then go through
71 ## the much smaller list to determine which of them are real matches
72 limit = l_s - l_t + 1;
73 v = find (s (1 : limit) == t(1) & s (2 : limit+1) == t (2)
74 & s (3 : limit+2) == t(3) );
75 endif
76
77 if (l_t > 3)
78
79 ## force strings to be both row vectors or both column vectors
80 if (all (size (s) != size (t)))
81 t = t.';
82 endif
83
84 ## search index vector for a match
85 ind = 0 : l_t - 1;
86 n = 0; # return 0 if loop terminates without finding any match
87 for idx = 1:length(v)
88 if (s (v(idx) + ind) == t)
89 n = v(idx);
90 break;
91 endif
92 endfor
93
94 elseif (length(v) > 0)
95 n = v(1);
96
97 else
98 n = 0;
99
100 endif
101
102 endfunction