39 lines
936 B
Matlab
39 lines
936 B
Matlab
% Count the number of connected triples in a graph.
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% Note: works for undirected graphs only
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%
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% INPUTs: adjacency matrix, nxn
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% OUTPUTs: integer - number of connected triples
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%
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% Other routines used: kneighbors.m, cycles3.m
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% GB: last updated, October 4, 2012
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function c=numConnTriples(adj)
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c=0; % initialize
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for i=1:length(adj)
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neigh=kneighbors(adj,i,1);
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if length(neigh)<2; continue; end % handle leaves, no triple here
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c=c+nchoosek(length(neigh),2);
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end
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c=c-2*cycles3(adj); % due to the symmetry triangles repeat 3 times
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% in the nchoosek count
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% alternative
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% def numConnTriples(L):
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%
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% % input: adjacency list
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% % outputs: number of connected triples
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%
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% c=0; % initialize number of connected triples
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%
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% for i=1:length(L)
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% neigh = L{i}
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% if length(neigh)<2: continue; end
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% c = c + nchoosek(length(neigh),2);
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% end
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%
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% c = c - 2*cycles3(adjL2adj(L));
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