Re: st: sortpreserve option

[David Kantor <kantor.d@att.net>]

At 06:29 PM 8/14/2013, you wrote:
> On Wed, Aug 14, 2013 at 5:15 PM, David Kantor <kantor.d@att.net> wrote:
> > At 03:14 PM 8/14/2013, Sergiy Radyakin wrote:
> >>
> >> What is the effect of inclusion of the -sortpreserve- option in the
> >> declaration of a program, which might change the number of
> >> observations? (add or remove)
> >
> >
> > My understanding is that it should have no effect on the number of
> > observations.
> Dear David, just to make sure we are talking about the same thing. The
> program _is expected_ to make changes to data by adding/removing
> observations. Can I still declare it -sortpreserve-?
> Specifically, what will happen to the newly added observations? will
> they end up in the end of the restored-order-dataset? in the beginning
> of it? (elsewhere if other possibilities exist?)

Interesting question. I don't know, though I can imagine a few 
possibilities. It might


> > Its effect is to insure that when the program exits, the data are left in
> > the same sort order as before.
>
> Yes, that's by the book. But we now have more data, so how would Stata
> know where to put the new observations which it hasn't seen before?
>
> > That may or may not be desirable, depending on your needs.
> If there is reasonable/predictable/logical behavior of sortpreserve in
> this case I definitely like to know it. Whether it is desirable,
> depends on what it is.
>
> Best, Sergiy Radyakin
>
> > It may take a little extra run-time.
> >
> > I have written one program where I made it an option -- whether 
> to run it as
> > sortpreserve. There was a little trick to make that happen, which I can
> > explain if you want.
>
> I envision this as:
> http://radyakin.org/statalist/2013081401/myprog.ado
> with any sort-destructive actions to be taken in the common part.
> Perhaps it can be more elegant, but this is not what I am looking for now.
>
> Thank you for your help
> Sergiy
>
> > HTH
> > --David
> >
> >
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