Re: [Gretl-devel] "NA" revisited
On Tue, 24 Jul 2018, Sven Schreiber wrote:
Am 24.07.2018 um 17:27 schrieb Allin Cottrell:
>
>> Am 24.07.2018 um 16:18 schrieb Allin Cottrell:
>>> Following discussions between Jack and myself, here's a sort of
>>> "RFC" for changing the internal definition of "NA" in
gretl, which we
>>> believe can be done with full backward compatibility.
>>>
> Yes, I think "nice feature but we don't have it currently" is about
right.
> Consider the following (abdata has lots of missing values, including the
> very first observation):
>
> <hansl>
> open abdata.gdt
> WAGE[1] = WAGE[1] * 0
>
...
> The first "print" shows that the leading NA for WAGE has indeed been
> changed to 0 (defensibly).
...
>
> Under the proposed scheme NAs (= nans) would not turn into zeros on
> multiplication by zero -- but the misszero() function would still be
> available to do that job.
OK, but doesn't this consitute a counterexample to the claim of full
backward compatibility?
Yes, you're right. I hadn't thought that through all the way.
This doesn't have to be bad, given the perhaps kind of flaky
behavior currently, but it would change something, no?
It raises a compatibility issue if there are scripts out there that
depend on multiplication by 0 to neutralize NAs. I guess that's
unlikely, given misszero(), but clearly we'd have to check all
function packages, at least.
Allin