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Re: st: re: Matrix question


From   brendan.halpin@ul.ie (Brendan Halpin)
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: re: Matrix question
Date   Mon, 06 Feb 2012 09:53:22 +0000

Thanks, that's exactly what I was looking for!

On Mon, Feb 06 2012, Christopher Baum wrote:

> Probably some more elegant way of generating the transformation matrix, but:
>
> mata
> bigmat = runiform(15,6)
> trans = J(1, 5, 1/5)
> zer = J(1,5,0)
> transmat = (trans, zer, zer \ zer, trans, zer \ zer, zer, trans)
> reduced = transmat * bigmat
> bigmat
> reduced
> end

Yes, there's an easy way of generating the transformation matrix, which
is also easy to adapt for different sizes of the data matrix. 

mm_expand(diag(J(1, 3, 1/5)), J(1, 1, 1), J(1, 3, 5))

mm_expand is from Ben Jann's more_mata.

Brendan
-- 
Brendan Halpin,   Department of Sociology,   University of Limerick,   Ireland
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