Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / conndef.m

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+## Copyright (C) 2004 Josep Mones i Teixidor
+##
+## 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 2 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{conn} = } conndef (@var{num_dims}, @var{type})
+## Creates a connectivity array.
+##
+## @code{conn=conndef(num_dims,type)} creates a connectivity array
+## (@var{CONN}) of @var{num_dims} dimensions and which type is defined
+## by @var{type} as follows:
+## @table @code
+## @item minimal
+## Neighbours touch the central element on a (@var{num_dims}-1)-dimensional
+## surface.
+## @item maximal
+## Neighbours touch the central element in any way. Equivalent to
+## @code{ones(repmat(3,1,@var{num_dims}))}.
+## @end table
+##
+## @end deftypefn
+
+
+
+## Author:  Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function conn = conndef(num_dims,conntype)
+  if(nargin!=2)
+    usage("conn=conndef(num_dims, type)");
+  endif
+  if(num_dims<=0)
+    error("conndef: num_dims must be > 0");
+  endif
+    
+  if(strcmp(conntype,"minimal"))
+    if(num_dims==1)
+      conn=[1;1;1];
+    elseif(num_dims==2)
+      conn=[0,1,0;1,1,1;0,1,0];
+    else
+      conn=zeros(repmat(3,1,num_dims));
+      idx={};
+      idx{1}=1:3;
+      for i=2:num_dims
+       idx{i}=2;
+      endfor
+      conn(idx{:})=1;
+      for i=2:num_dims
+       idx{i-1}=2;
+       idx{i}=1:3;
+       conn(idx{:})=1;
+      endfor
+    endif
+    
+  elseif(strcmp(conntype,"maximal"))
+    if(num_dims==1)
+      conn=[1;1;1];
+    else
+      conn=ones(repmat(3,1,num_dims));
+    endif
+  else
+    error("conndef: invalid type parameter.");
+  endif
+  
+endfunction
+
+%!demo
+%! conndef(2,'minimal')
+%! % Create a 2-D minimal connectivity array
+
+%!assert(conndef(1,'minimal'), [1;1;1]);
+
+%!assert(conndef(2,'minimal'), [0,1,0;1,1,1;0,1,0]);
+
+%!test
+%! C=zeros(3,3);
+%! C(2,2,1)=1;
+%! C(2,2,3)=1;
+%! C(:,:,2)=[0,1,0;1,1,1;0,1,0];
+%! assert(conndef(3,'minimal'), C);
+
+%!assert(conndef(1,'maximal'), ones(3,1));
+%!assert(conndef(2,'maximal'), ones(3,3));
+%!assert(conndef(3,'maximal'), ones(3,3,3));
+%!assert(conndef(4,'maximal'), ones(3,3,3,3));
+
+
+
+% $Log$
+% Revision 1.3  2007/03/23 16:14:36  adb014
+% Update the FSF address
+%
+% Revision 1.2  2007/01/04 23:41:47  hauberg
+% Minor changes in help text
+%
+% Revision 1.1  2006/08/20 12:59:32  hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.2  2005/07/03 01:10:19  pkienzle
+% Try to correct for missing newline at the end of the file
+%
+% Revision 1.1  2004/08/15 19:38:44  jmones
+% conndef added: Creates a connectivity array