[Gretl-devel] smpl <condition> --restrict --permanent

Allin Cottrell cottrell at wfu.edu
Thu Jul 2 10:02:03 EDT 2015

On Thu, 2 Jul 2015, Sven Schreiber wrote:

> Am 02.07.2015 um 01:46 schrieb Allin Cottrell:
>> So here's my proposal: in the circumstances described above, if
>> you issue a command to shrink the dataset permanently, gretl checks to
>> see whether all saved models fall under the "easy case". If so, fine. If
>> not, you get a warning that not all saved models can be preserved, with
>> a "Go ahead? Yes/No" dialog. If you say "Yes", we
>> destroy all the models that would turn into zombies.
>> Any comments/suggestions?
> I don't remember the discussion leading to "--permanent" (hopefully it
> wasn't my request...),

As I recall, the point was: If I want to shift (fully) to a restricted 
version of my dataset, why do I have to apply the restriction, save 
the restricted dataset, then reopen the restricted version (hence 
losing my existing "session")? Why can't I just apply a permanent 
restriction on the fly?

> but anyway. In principle the idea sounds good. A couple of 
> questions:
> First, what happens if you do --permanent via script? Do you still 
> get a dialog?

Yes, you should (not now, but per the proposal). In the same way that 
you get a dialog if you run a script that opens a new dataset from 
file, when there's a dataset already in place.

> I guess not, but what happens instead? I guess there would be a
> case to halt with an error. However, this would also suggest the
> possibility to save the current session (to .gretl) via script commands,
> something which currently isn't possible AFAIK.

That might be worth adding anyway.

> Secondly, the current status quo of the session right before --permanent
> could be saved "automatically" in a kind of snapshot .gretl session
> file. In essence, this would be a step towards a kind of autosave
> feature which may be nice in any case.

I took Lee's point (at the gretl conference) about autosave for the 
gretl script editor. I'm not so sure about autosave for gretl 

The proposed dialog, instead of offering just Yes/No for going
ahead with a model-destroying sample restriction, could offer a 
three-way choice:

* Back off, don't do the restriction
* Go ahead, never mind the models
* Save the current session then go ahead

> Third, why actually is --permanent not available for regular sample
> selection (without --restrict etc.)? It says so in the docs, and in the
> GUI only the corresponding dialog(s?) have that option, but I don't see
> the reason right now.

OK, that's debatable, but it would add extra complications. A defence 
of the existing situation is that it's easier to see a use-case for
wanting a "subsampling" restriction to be made permanent on the fly 
(as opposed to a t1, t2 setting) since in the former case (only) the 
dataset is basically duplicated in memory, which can become a problem 
with big data.

> Finally, what does for example Eviews do? They also have
> equation/system/model objects. Perhaps they even disallow to throw away
> the data then. I could check if that were interesting.

Yes, that might be interesting.


More information about the Gretl-devel mailing list