7:19 p.m.
I've had my head down in dbnomics stuff lately (informative posting
to come before long), but I noticed in passing some comments/queries
about series in bundles. I'm afraid I've lost the references but
I'll post on the topic in general.
The thing to remember is that bundles are just a transport mechanism
for series. You can't "really" have a series in a bundle, since
series belong to datasets and bundles know absolutely nothing about
datasets; you can only have the ghost of a series.
A "series" in a bundle has a status akin to a soul being rowed
across the Styx by Charon, with the difference that it is possible
to regain the living side under the right circumstances (the
ghost-series is extracted into a conformable dataset).
Allin
12:11 p.m.
Am 04.07.2018 um 01:19 schrieb Allin Cottrell:
I've had my head down in dbnomics stuff lately (informative
posting to
come before long), but I noticed in passing some comments/queries
about series in bundles. I'm afraid I've lost the references but I'll
post on the topic in general.
Perhaps one of those comments was my post from June 29th.
The thing to remember is that bundles are just a transport mechanism
for series. You can't "really" have a series in a bundle, since series
belong to datasets and bundles know absolutely nothing about datasets;
you can only have the ghost of a series.
A "series" in a bundle has a status akin to a soul being rowed across
the Styx by Charon, with the difference that it is possible to regain
the living side under the right circumstances (the ghost-series is
extracted into a conformable dataset).
Very nice metaphor! I wonder how this whole affair should be
communicated to script writers. Maybe it should be pointer-to-series
instead of series in a bundle then?
How is the "ghost" actually kept in the bundle? By ID number, and if so,
what happens upon renumbering? Or by name?
thanks,
sven
4:51 p.m.
On Wed, 4 Jul 2018, Sven Schreiber wrote:
Am 04.07.2018 um 01:19 schrieb Allin Cottrell:
> I've had my head down in dbnomics stuff lately (informative posting to come
> before long), but I noticed in passing some comments/queries about series
> in bundles. I'm afraid I've lost the references but I'll post on the
topic
> in general.
Perhaps one of those comments was my post from June 29th.
Yes, I think so.
> The thing to remember is that bundles are just a transport
mechanism for
> series. You can't "really" have a series in a bundle, since series
belong
> to datasets and bundles know absolutely nothing about datasets; you can
> only have the ghost of a series.
>
> A "series" in a bundle has a status akin to a soul being rowed across the
> Styx by Charon, with the difference that it is possible to regain the
> living side under the right circumstances (the ghost-series is extracted
> into a conformable dataset).
Very nice metaphor! I wonder how this whole affair should be communicated to
script writers. Maybe it should be pointer-to-series instead of series in a
bundle then?
I need to look back at the doc and see what's there now. I'll try to
do that soon.
How is the "ghost" actually kept in the bundle? By ID
number, and
if so, what happens upon renumbering? Or by name?
By ID number or name would be too fragile, given that series can be
deleted or renamed. We store in the bundle an array of "doubles"
along with a record of its length. This array can be pulled back out
as a series if its length matches that of the current dataset
(either its total length or the current sample size).
Here's a little llustration:
<hansl>
open data4-1
bundle b
series b.y = price
series by = b.y
print --byobs
smpl 3 10
series b.x = sqft
series by2 = b.y # OK
series bx = b.x
smpl full
print --byobs
</hansl>
What you can't do is simply index into a "series" within a bundle:
we don't know if that's a valid operation until we try pulling it
out.
Allin
4:33 a.m.
Am 06.07.2018 um 22:51 schrieb Allin Cottrell:
On Wed, 4 Jul 2018, Sven Schreiber wrote:
> How is the "ghost" actually kept in the bundle? By ID number, and if
> so, what happens upon renumbering? Or by name?
By ID number or name would be too fragile, given that series can be
deleted or renamed. We store in the bundle an array of "doubles" along
with a record of its length. This array can be pulled back out as a
series if its length matches that of the current dataset (either its
total length or the current sample size).
Hm, but the same thing can be done with a matrix (vector), no? Then
what's really the difference between a series and a matrix in a bundle?
Plain series can be used in gretl commands, but AFAIK you can't put
series-in-bundles directly in commands (as in ols b.y const b.x), either
- for certain reasons that we have discussed previously.
My feeling is that either some meta data needs to be attached to a
series, or otherwise the official recommendation perhaps should be to go
via matrix explicitly. Not that I'm pushing for the first option, just
thinking in terms of coherent design.
thanks,
sven
2325
days inactive
2329
days old
3 comments
2 participants
participants (2)
-
Allin Cottrell -
Sven Schreiber