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Re: random sort
From: |
Heber Farnsworth |
Subject: |
Re: random sort |
Date: |
Tue, 2 Dec 2003 22:49:20 -0600 |
I think your problem is that you are trying to sort something the same
size as X when you really only want to sort a vector with as many
elements as X has columns.
If X is NxM then do
[S I] = sort(rand(N,1));
Y = X(:,I);
and Y has the same columns as X but in shuffled order.
You didn't mention whether you wanted to sample with replacement or
not. This just re-orders the columns. It's a different trick if you
want to admit the possibility that some columns of X may not show up in
Y while others are repeated. That's what you would do if you were
boostrapping data for instance.
Heber
On Tuesday, December 2, 2003, at 09:02 PM, Mike Miller wrote:
I don't know why I can't figure this out! I'd swear I've done it
before.
What's the trick to sorting columns in random order? I have a matrix
with
many columns. Suppose the matrix is called 'X'. It seems like I
should
be able to use something like this:
[S, I] = sort(rand(size(X)));
Then I can use 'I' to sort the columns of X, right? But how? I just
know
there's an easy trick.
Thanks in advance for breaking my mental block.
Mike
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Octave is freely available under the terms of the GNU GPL.
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Subscription information: http://www.octave.org/archive.html
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- random sort, Mike Miller, 2003/12/02
- Re: random sort,
Heber Farnsworth <=