All combinations of matrix elements?
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Hello,
I'd like to find all combinations of 2 elements in a matrix.
For example, a = [1:4; 5:8; 9:12]', the result should be [1*1 1*2 1*3 1*4 1*5 ... 1*12 2*2 2*3 ... 2*12 3*3 ... 12*11 12*12]';
Thanks for your help!
Risposta accettata
Stephen23
il 23 Set 2016
Modificato: Stephen23
il 27 Set 2016
Method One: matrix multiply and tril:
>> z = a(:) * a(:)'
>> z(tril(true(size(z))))
>> prod(a(combinator(numel(a),2,'c','r')),2)
5 Commenti
Stephen23
il 26 Set 2016
@Xiaohan Du: cell arrays are containers for other data classes. They cannot have mathematical operations applied to them. Whatever you want to do (it is not clear to me) needs to be applied to a numeric array, not a cell array.
James Tursa
il 26 Set 2016
@Xiaohan Du: It is unclear what solution you really want from your original post. Stephen's answer does the entire outer product, which does not match your example result which appears to be only one triangular portion of the outer product. Andrei's answer does this triangular portion which matches your original post example result. What is it you really want? (The accepted answer does not match the question example result)
Più risposte (1)
Andrei Bobrov
il 23 Set 2016
Modificato: Andrei Bobrov
il 23 Set 2016
b = a(:)*a(:).';
out = b(tril(true(size(b))));
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