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Re: st: Re: Mata for data management

From   "Scott Merryman" <[email protected]>
To   [email protected]
Subject   Re: st: Re: Mata for data management
Date   Thu, 31 Jan 2008 21:14:58 -0600

On Jan 31, 2008 8:48 PM, Gabi Huiber <[email protected]> wrote:
> I'm trying to cheat and speed things up a bit when dealing with a
> bunch of files with names such as fileYYYYMMDD.dta. I could collect
> the numeric part of the names in a column vector that starts with the
> initial values a=J({potential number of files}, 1,0). But there is a
> fair chance that my YYYYMMDD succession has gaps, so at the end of the
> process this column vector will have some zeroes.
> I would like to do this:
> mata
> a=sort(a,1)
> Then drop all the zero elements of a, and end up with a shorter
> vector. But I can't find anything like "drop rows" in the Mata book or
> Google. Any ideas?

-select()- ?

A = (1,2,3,4,0,5,6,0,0,7)
A2 = select(A, A:>0)

> Generally, some R-like way to deal with arrays would be nice to have
> in Mata or Stata.

How do R arrays work?

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