[email protected] schrieb am 19/02/2009 17:39:52:
> All--
> Loading the whole dataset may hog memory, but
> use in 1 using...
> works fine, as shown in my previous post. -describe- would be
> preferable, since it does not load the data in memory at all, but it
> does not save a list of variables, and _describe is built-in, hence
> not hackable.
But it does save the list of variables in a local macro, if you choose the
option [varlist] - or am I missing a point? The problem is - as Martin
suggested - that this local macro is limited to a low number of characters
(244) which might not be enough in many occasions.
Johannes
It would be possible to write a program that loads no
> data and gets all the variable lists, either by parsing the output of
> _describe using -file- commands, or as is Sergiy's wont, via a direct
> file-access approach. But it wouldn't be nice if there were a Mata
> command to get a view onto a dataset not in memory?
>
> On Thu, Feb 19, 2009 at 11:24 AM, Johannes Geyer <[email protected]> wrote:
> > what about:
> >
> > *************
> > clear*
> > sysuse auto, clear
> > drop gear_ratio displacement
> > save newauto, replace
> > sysuse auto, clear
> > qui ds
> > loc first `r(varlist)'
> >
> > des using auto, varlist
> >
> > loc second `r(varlist)'
> > loc diff: list first - second
> > di in red "Differences: `diff'"
> > *************
> >
> > -describe- does not need to load the dataset which may be of interest
here
> >
> >
> > Johannes
> >
> *
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