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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 d = grPropagateDistance(v, e, v0, l)
%GRPROPAGATEDISTANCE Propagates distances from a vertex to other vertices.
%
% DISTS = grPropagateDistance(V, E, V0, L)
% V0 is index of initial vertex
% E is array of source and target vertices
% L is the vector of length of each edge. If not specified, length 1 is
% assumed for all edges.
% The result DISTS is a column array with as many rows as the number of
% vertices, containing the geodesic distance of each vertex to the vertex
% of index V0.
%
% Example
% nodes = [20 20;20 50;20 80;50 50;80 20;80 50;80 80];
% edges = [1 2;2 3;2 4;4 6;5 6;6 7];
% figure; drawGraph(nodes, edges);
% axis([0 100 0 100]); axis equal; hold on
% DISTS = grPropagateDistance(nodes, edges, 2)
% DISTS =
% 1
% 0
% 1
% 1
% 3
% 2
% 3
% drawNodeLabels(nodes+1, DISTS);
%
% See also
% graphRadius, graphCenter, graphDiameter, graphPeripheralVertices
% grVertexEccentricity
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2010-09-07, using Matlab 7.9.0.529 (R2009b)
% Copyright 2010-2023 INRA - Cepia Software Platform
% initialize empty array for result
Nv = length(v);
d = ones(Nv, 1)*inf;
d(v0) = 0;
% ensure there is a valid length array
if nargin < 4
l = ones(size(e,1), 1);
end
% iterate from germ vertex until there are no more vertices to process
verticesToProcess = v0;
while ~isempty(verticesToProcess)
% init new iteration
newVerticesToProcess = [];
% iterate over vertices that need to be updated
for i = 1:length(verticesToProcess)
vertex = verticesToProcess(i);
% iterate over neighbor edges of current vertex
vertexEdges = grAdjacentEdges(e, vertex);
for j = 1:length(vertexEdges)
iEdge = vertexEdges(j);
% compute distance between current vertex and its neighbor
vertex2 = grOppositeNode(e(iEdge,:), vertex);
newDist = d(vertex) + l(iEdge);
% update geodesic distance of neighbor node if needed
if newDist < d(vertex2)
d(vertex2) = newDist;
newVerticesToProcess = [newVerticesToProcess ; vertex2]; %#ok<AGROW>
end
end
end
% update set of vertices for next tieration
verticesToProcess = newVerticesToProcess;
end
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