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convert adjacency matrix to edge list

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muhammad ismat
muhammad ismat on 16 Feb 2017
Answered: Ratha Pech on 19 Mar 2017
if i have this code
function el=adj2edge(adj)
n=length(adj); % number of nodes
edges=find(adj>0); % indices of all edges
el=[];
for e=1:length(edges)
[i,j]=ind2sub([n,n],edges(e)); % node indices of edge e
el=[el; i j adj(i,j)];
end
to convert adjacency matrix to edgelist i.e if i input
0 1 1
1 0 0
1 0 0
the output is
2 1 1
3 1 1
1 2 1
1 3 1
but i want
1 2
1 3
only

Answers (2)

Walter Roberson
Walter Roberson on 16 Feb 2017
Remove the third column. Sort along the second dimension. unique() by rows.

Ratha Pech
Ratha Pech on 19 Mar 2017
Replace the line edges=find(adj>0); % indices of all edges with edges=find(triu(adj>0)); % indices of all edges

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