Vectors seen as a combination of other vector's elements
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Hi everyone.
I have a problem that I think to be quite easy, but I can't succeed in solving it.
I have four vectors of different length (a, b, c, d). I'd like to have a final vector (V) which contains all the combinations of their elements.
eg, if I had a = [1 2 3], b = [4 5], c = [6], V should be [1 4 6; 1 5 6; 2 4 6; 2 5 6; 3 4 6; 3 5 6].
Now I'm using four nested for cycle, but I'd like to find a faster solution, without using the cycle but maybe some logical solutions.
Thank you in advance. Luca
P.S. I leave the portion of my code:
for n = 1:length(comb_n)
for i = 1:length(comb_i)
for c = 1:length(comb_c)
for a = 1:length(comb_a)
combinations(index,1:number_surrogates) = [comb_n(n,:), comb_i(i,:), comb_c(c,:), comb_a(a,:)];
index = index+1;
end
end
end
end
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Answers (2)
Guillaume
on 12 Apr 2019
This is the generic version of Madhan's answer. Works for any (reasonable!) number of inputs.
in = {[1, 2, 3], [4, 5], 6}; %cell array of vectors.
combs = cell(size(in));
[combs{:}] = ndgrid(in{:});
combs = reshape(cat(numel(combs) + 1, combs{:}), [], numel(combs));
6 Comments
madhan ravi
on 12 Apr 2019
Same thought as Torsten's but your question is most likely solved by Guillaume's method.
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