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comparison scripts/strings/rindex.m @ 3911:8389e78e67d4

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[project @ 2002-04-28 02:15:38 by jwe]
author jwe
date Sun, 28 Apr 2002 02:15:39 +0000
parents f8dde1807dee
children 48a39e2b2ab7
comparison
equal deleted inserted replaced
3910:79a90a0f0eff 3911:8389e78e67d4
39 39
40 if (nargin != 2) 40 if (nargin != 2)
41 usage ("rindex (s, t)"); 41 usage ("rindex (s, t)");
42 endif 42 endif
43 43
44 n = 0; 44 if (!isstr (s) || !isstr (t) || all (size (s) > 1) || all (size (t) > 1) )
45
46 if (isstr (s) && isstr (t))
47
48 l_s = length (s);
49 l_t = length (t);
50
51 if (l_t <= l_s)
52 tmp = l_s - l_t + 1;
53 for idx = tmp : -1 : 1
54 if (strcmp (substr (s, idx, l_t), t))
55 n = idx;
56 return;
57 endif
58 endfor
59 endif
60
61 else
62 error ("rindex: expecting string arguments"); 45 error ("rindex: expecting string arguments");
63 endif 46 endif
64 47
48 l_s = length (s);
49 l_t = length (t);
50
51 if ( l_s == 0 || l_s < l_t )
52 ## zero length source, or target longer than source
53 v = [];
54
55 elseif ( l_t == 0 )
56 ## zero length target: return last
57 v = l_s;
58
59 elseif ( l_t == 1 )
60 ## length one target: simple find
61 v = find (s==t);
62
63 elseif ( l_t == 2 )
64 ## length two target: find first at i and second at i+1
65 v = find (s (1 : l_s-1) == t (1) & s (2 : l_s) == t (2));
66
67 else
68 ## length three or more: match the first three by find then go through
69 ## the much smaller list to determine which of them are real matches
70 limit = l_s - l_t + 1;
71 v = find (s (1 : limit) == t(1) & s (2 : limit+1) == t (2)
72 & s (3 : limit+2) == t(3) );
73 endif
74
75 if (l_t > 3)
76
77 ## force strings to be both row vectors or both column vectors
78 if (all (size (s) != size (t)))
79 t = t.';
80 endif
81
82 ## search index vector for a match
83 ind = 0 : l_t - 1;
84 n = 0; # return 0 if loop terminates without finding any match
85 for idx = length(v):-1:1
86 if (s (v(idx) + ind) == t)
87 n = v(idx);
88 break;
89 endif
90 endfor
91
92 elseif (length(v) > 0)
93 n = v(length(v));
94
95 else
96 n = 0;
97
98 endif
99
65 endfunction 100 endfunction