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## Copyright (C) 2024 David Legland
## 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.
##
## The views and conclusions contained in the software and documentation are
## those of the authors and should not be interpreted as representing official
## policies, either expressed or implied, of the copyright holders.
function labels = grLabel(nodes, edges)
%GRLABEL Associate a label to each connected component of the graph.
%
% LABELS = grLabel(NODES, EDGES)
% Returns an array with as many rows as the array NODES, containing index
% number of each connected component of the graph. If the graph is
% totally connected, returns an array of 1.
%
% Example
% nodes = rand(6, 2);
% edges = [1 2;1 3;4 6];
% labels = grLabel(nodes, edges);
% labels =
% 1
% 1
% 1
% 2
% 3
% 2
%
% See also
% grAdjacentNodes
%
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2007-08-14, using Matlab 7.4.0.287 (R2007a)
% Copyright 2007-2023 INRA - BIA PV Nantes - MIAJ Jouy-en-Josas
% init
Nn = size(nodes, 1);
labels = (1:Nn)';
% iteration until stability
modif = true;
while modif
modif = false;
% compute the minimum label in the neighborhood of each node
for i = 1:Nn
neigh = grAdjacentNodes(edges, i);
neighLabels = labels([i;neigh]);
% check for a modification
if length(unique(neighLabels)) > 1
modif = true;
end
% put new labels
labels(ismember(labels, neighLabels)) = min(neighLabels);
end
end
% renumbering to have fewer labels
labels2 = unique(labels);
for i = 1:length(labels2)
labels(labels == labels2(i)) = i;
end
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