MATLAB: Cell comparison with other cells in different rows

cell arraycomparisonisequalismember

I have a 6×2 cell array. Each cell is a 1×2 cell that contains an x and y co-ordinate. I want to be able to compare the contents of each cell of every row with the contents of each cell of the other rows. Each row of the cell array stands for a line. Essentially what I need to do is to determine which rows are connected together by finding the common endpoint.
I saw something on here that I think I can utilize. It's called nchoosek. This function basically finds all possible rows combination's for a give size. The following code uses this function. The problem that I am having is that I get all zero's for the keys.
endpoints = {{-24.7697910000000,-15.8191235000000},{-20.6771670000000,-3.54125200000000};{-12.6771670000000,20.4587480000000},{-20.6771670000000,-3.54125200000000};{-11.9803417500000,-14.5401785500000},{13.0196582500000,-12.0401785500000};{-11.9803417500000,-14.5401785500000},{-24.7697910000000,-15.8191235000000};{4.32283300000000,-1.04125200000000},{-12.6771670000000,20.4587480000000};{4.32283300000000,-1.04125200000000},{13.0196582500000,-12.0401785500000}};
comparisons = nchoosek(1:size(endpoints,1),2);
N = size(comparisons,1);
keys = cell(N,1);
for j = 1:N
    keys{j}=isequal(endpoints{comparisons(j,1),:},endpoints{comparisons(j,2),:});
end

Best Answer

For the record, it would be better to use arrays rather than cell arrays for the coordinates (in fact for the whole thing, but that's ok).
Anyway, this should do the trick:
ep = {{-24.7697910000000,-15.8191235000000},{-20.6771670000000,-3.54125200000000};
    {-12.6771670000000,20.4587480000000},{-20.6771670000000,-3.54125200000000};
    {-11.9803417500000,-14.5401785500000},{13.0196582500000,-12.0401785500000};
    {-11.9803417500000,-14.5401785500000},{-24.7697910000000,-15.8191235000000};
    {4.32283300000000,-1.04125200000000},{-12.6771670000000,20.4587480000000};
    {4.32283300000000,-1.04125200000000},{13.0196582500000,-12.0401785500000}};
n = size(ep, 1);
V = nchoosek(1:n, 2);
key = false(n, 1);
% Convert the points to vectors
ep = cellfun(@(x) cell2mat(x), ep, 'UniformOutput', false);
is_same = @(x, y) norm(x - y, inf) / norm(x, inf) < 100*eps;
for i = 1:size(V, 1)
   % Do the four comparisons
   i1 = V(i,1);
   i2 = V(i,2);
   key(i) = is_same(ep{i1, 1}, ep{i2, 1}) || ...
            is_same(ep{i1, 1}, ep{i2, 2}) || ...
            is_same(ep{i1, 2}, ep{i2, 2}) || ...
            is_same(ep{i1, 2}, ep{i2, 2});
end
matches = V(key, :);
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