matlab function to build a adjacency matrix from a xy list

build_adjacency_from_list.m

function A = build_adjacency_from_list(ij)

% function A = build_adjacency_from_list(ij)
%
% ij: row, column

A = zeros(max(max(ij)),max(max(ij)));

for i = 1:length(ij)
    A(ij(i,1), ij(i,2)) = 1;
end

if ~issymmetric(A)
    A = A + A';
end

end