Re: [R] Two ?'s:Permuting a data matrix and projection operator

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From: Achim Zeileis (zeileis@ci.tuwien.ac.at)
Date: Thu 20 Sep 2001 - 18:07:20 EST 

Message-id: <3BA9A3B8.522437A@ci.tuwien.ac.at>

"J. Wan" wrote:
>
> Hi!
>
> I have two questions:
>
> 1. Is there an easy way/algorithm to obtain a series of permutated data
> matrices which are obtained by permuting all the elements within each row?
>
> Or is there a function that can permute all the elements for each row
> instead of the whole matrix?

sample() can do random permutations, so if you want a permutation of the
elements within each row of a matrix X, this 

t(apply(X,1,sample))

could do the job
Z

> 2. Is there a function which helps find a matrix... projection operator
> from p dimensional to p-1 dimensional subspace orthogonal to x, a real
> number?
>
> Thanks for your help!
>
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