--- /dev/null
+%% Copyright (C) 2008-2012 David Legland <david.legland@grignon.inra.fr>
+%% All rights reserved.
+%%
+%% Redistribution and use in source and binary forms, with or without
+%% modification, are permitted provided that the following conditions are met:
+%%
+%% 1 Redistributions of source code must retain the above copyright notice,
+%% this list of conditions and the following disclaimer.
+%% 2 Redistributions in binary form must reproduce the above copyright
+%% notice, this list of conditions and the following disclaimer in the
+%% documentation and/or other materials provided with the distribution.
+%%
+%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
+%% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+%% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+%% ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
+%% ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+%% DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+%% SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+%% CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+%% OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+%% OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+%%
+%% 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
+
+%% -*- texinfo -*-
+%% @deftypefn {Function File} {@var{edges} = } knnGrpah (@var{nodes})
+%% Create the k-nearest neighbors graph of a set of points
+%%
+%% EDGES = knnGraph(NODES)
+%%
+%% Example
+%% @example
+%%
+%% nodes = rand(10, 2);
+%% edges = knnGraph(nodes);
+%% drawGraph(nodes, edges);
+%%
+%% @end example
+%%
+%% @end deftypefn
+
+function edges = knnGraph(nodes, varargin)
+
+ % get number of neighbors for each node
+ k = 2;
+ if ~isempty(varargin)
+ k = varargin{1};
+ end
+
+ % init size of arrays
+ n = size(nodes, 1);
+ edges = zeros(k*n, 2);
+
+ % iterate on nodes
+ for i = 1:n
+ dists = distancePoints(nodes(i,:), nodes);
+ [dists inds] = sort(dists); %#ok<ASGLU>
+ for j = 1:k
+ edges(k*(i-1)+j, :) = [i inds(j+1)];
+ end
+ end
+
+ % remove double edges
+ edges = unique(sort(edges, 2), 'rows');
+
+endfunction
+
+%!demo
+%! nodes = rand(10, 2);
+%! edges = knnGraph(nodes);
+%! drawGraph(nodes, edges);
+%! axis tight