Vectorizing a for loop in MATLAB/Octave

Question

My question is: is there a way to vectorize this operation in MATLAB/Octave?

y = %a (m x 1) vector, with every entry in [1, 10]
y2 = repmat(1 : 10, [m 1]);
for i = 1 : m
    y2(i, :) = (y2(i, :) == y(i));
end

@macduff: I don't seem to get the correct result with kron. — Jonas
– Jonas, Commented Sep 25, 2012 at 15:06
@Jonas, thanks for questioning me, I got a little hasty with my comment. :-) — macduff
– macduff, Commented Sep 25, 2012 at 15:26

Jonas · Accepted Answer · 2012-09-25 15:04:22Z

4

bsxfun is a good way of both expanding and vectorizing computations (it will perform a multithreaded computation if it's beneficial).

m = 10;

y = randperm(m);

y2 = bsxfun(@eq,y,(1:m)')';

answered Sep 25, 2012 at 15:04

Jonas

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1 Comment

@JoseRamirez: Please consider accepting the answer if you consider it helpful