Run function for paired data?
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Hi,
Let's say I have a 10x10 matrix A. I wish to run each unique pair of elements from that matrix (e.g. (1,1),(1,2),...,(1,10) - not to repeat (2,1) for instance) in a function that I have. Any ideas how this can be possible?
Thanks!
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Accepted Answer
Geoff Hayes
on 28 Jan 2015
Fred - if you just want to loop over each unique pair of elements in the matrix, then consider doing something like
% assume A is 2D
[r,c] = size(A);
for m=1:r
for n=m:c
% do something with pair (m,n)
end
end
Try the above and see what happens!
2 Comments
Geoff Hayes
on 30 Jan 2015
Yes, if you assume that the matrix is square and you want loop over each pair (and not the unique ones) then you can do as above (though use c for the number of columns for the case where your matrix is not square). And yes, you can write your output matrix as described above (consider pre-sizing it since you know the dimensions).
More Answers (1)
Guillaume
on 28 Jan 2015
To get your pair indices:
maxpair = 10; %? a 10x10 matrix has 100 elements.
indices = [repmat([1:maxpair]', 1, 2); nchoosek(1:maxpair, 2)]
You can then use each row of indices as indices into your matrix:
m = randi(1000, 10, 10); %for example
maxpair = numel(m);
indices = [repmat([1:maxpair]', 1, 2); nchoosek(1:maxpair, 2)];
pairs = cellfun(@(row) m(row), num2cell(indices, 2), 'UniformOutput', false) %is this what you want?
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