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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 edges = adjacencyListToEdges(adjList)
%ADJACENCYLISTTOEDGES Convert an adjacency list to an edge array.
%
% EDGES = adjacencyListToEdges(ADJ)
% Converts the adjacency list ADJ, given as a cell array of adjacent
% indices, to an edge array.
%
% Example
% % create adjacency list for a simple graph
% adj = {[2 3], [1 4 5], [1 4], [2 3 5], [2 4]};
% edges = adjacencyListToEdges(adj)
% edges =
% 1 2
% 1 3
% 2 4
% 2 5
% 3 4
% 4 5
%
% See also
% graphs, polygonSkeletonGraph
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2020-06-02, using Matlab 9.8.0.1323502 (R2020a)
% Copyright 2020-2023 INRAE - BIA Research Unit - BIBS Platform (Nantes)
% count total number of edges
ne = 0;
for iVertex = 1:length(adjList)
ne = ne + length(adjList{iVertex});
end
% allocate memory
edges = zeros([ne 2]);
% create edges by iterating on vertices
ie = 0;
for iVertex = 1:length(adjList)
neighs = adjList{iVertex};
for iNeigh = 1:length(neighs)
edge = sort([iVertex neighs(iNeigh)]);
ie = ie + 1;
edges(ie,:) = edge;
end
end
% sort edges
edges = unique(edges, 'rows');
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