X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?p=CreaPhase.git;a=blobdiff_plain;f=octave_packages%2Fstrings-1.1.0%2Feditdistance.m;fp=octave_packages%2Fstrings-1.1.0%2Feditdistance.m;h=45269d815cadef8b9a8940603b572295c564b5a1;hp=0000000000000000000000000000000000000000;hb=c880e8788dfc484bf23ce13fa2787f2c6bca4863;hpb=1705066eceaaea976f010f669ce8e972f3734b05

diff --git a/octave_packages/strings-1.1.0/editdistance.m b/octave_packages/strings-1.1.0/editdistance.m
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+## Copyright (C) 2006 Muthiah Annamalai <muthiah.annamalai@uta.edu>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{dist},@var{L}] =} editdistance (@var{string1}, @var{string2}, @var{weights})
+## Compute the Levenshtein edit distance between the strings @var{string1} and
+## @var{string2}. This operation is symmetrical.
+##
+## The optional argument @var{weights} specifies weights for the
+## deletion, matched, and insertion operations; by default it is set to
+## +1, 0, +1 respectively, so that a least editdistance means a 
+## closer match between the two strings. This function implements
+## the Levenshtein edit distance as presented in Wikipedia article,
+## accessed Nov 2006. Also the levenshtein edit distance of a string
+## with an empty string is defined to be its length.
+## 
+## The default return value is @var{dist} the edit distance, and
+## the other return value  @var{L} is the distance matrix.
+##
+## @example
+## @group
+##          editdistance('marry','marie') 
+##          ##returns value +2 for the distance.
+## @end group
+## @end example
+##
+## @end deftypefn
+
+function [dist, L] = editdistance (str1, str2, weights)
+  if(nargin < 2 || (nargin == 3 && length(weights)  < 3) )
+    print_usage();
+  end
+  
+  L1=length(str1)+1;
+  L2=length(str2)+1;
+  L=zeros(L1,L2);
+  
+  if(nargin < 3)
+    g=+1;%insertion
+    m=+0;%match
+    d=+1;%deletion
+  else
+    g=weights(1);
+    m=weights(2);
+    d=weights(3);
+  end
+
+  L(:,1)=[0:L1-1]'*g;
+  L(1,:)=[0:L2-1]*g;
+  
+  m4=0;
+  for idx=2:L1;
+    for idy=2:L2
+      if(str1(idx-1)==str2(idy-1))
+        score=m;
+      else
+        score=d;
+      end
+      m1=L(idx-1,idy-1) + score;
+      m2=L(idx-1,idy) + g;
+      m3=L(idx,idy-1) + g;
+      L(idx,idy)=min(m1,min(m2,m3));
+    end
+  end
+  
+  dist=L(L1,L2);
+endfunction