How to permute a row vector without using perms(), permute() etc.

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Yuval
Yuval 2013-3-27
I would like to permute a row vector, but without using perms(), permute() and so forth. I was wondering whether the following code answers these requirements. I mean, am I somewhat "cheating" by using randi()? I'd also appreciate any comments on the algorithm in general (although I know the function works well).
function Y = ex(X)
Y = zeros(1,length(X));
for i = 1:length(X)
d = randi(length(X));
Y(i) = X(d);
X(d) = [];
end

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Matt J
Matt J 2013-3-27
编辑：Matt J 2013-3-27
It doesn't violate any requirements that you've mentioned, so I'm inclined to say it's legal. Here's another way, if you don't like randi for some reason
n=length(X);
[~,~,e]=qr(sprand(n,n,1/n));
Y=reshape(e*X(:),size(X)),
If the permuted order is supposed to be random, I don't think there's any avoiding the use some sort of random number generator.
  2 个评论
Yuval
Yuval 2013-3-27
编辑：Yuval 2013-3-27
Is it "legal" that my code changes the original vector?
Matt J
Matt J 2013-3-27
Only you and presumably the instructor who assigned this to you can know what is "legal" for you.

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