[Rd] data frame subset patch, take 2

[Martin Maechler]

>>>>> "MM" == Martin Maechler <maechler at stat.math.ethz.ch>
>>>>>     on Sat, 16 Dec 2006 22:31:21 +0100 writes:

>>>>> "Vladimir" == Vladimir Dergachev <vdergachev at rcgardis.com>
>>>>>     on Wed, 13 Dec 2006 13:03:21 -0500 writes:

    Vladimir> On Wednesday 13 December 2006 6:01 am, Martin Maechler wrote:
    >>> 
    >>> - Vladimir, have you verified your 'take2' against recent versions
    >>> of R-devel?

    Vladimir> Yes. 

    MM> indeed it applies cleanly

    >>> - If they still work, could you re-post them to R-devel, this
    >>> time using a proper MIME type,
    >>> i.e. most probably one of
    >>> application/x-tar
    >>> application/x-compressed-tar
    >>> application/x-gzip
    >>> 
    >>> In case you don't know how to achieve this,
    >>> I'd be interested to get it by "private" e-mail.

    Vladimir> No problem. The old e-mail did have a mime type: "text/x-diff".
    Vladimir> I am resending the patch - now compressed, hopefully it will get pass whatever 
    Vladimir> filters are in place.

    MM> It did pass --- and  "text/x-diff" should pass through too from
    MM> now on.

    MM> However, even though the patch looks quite ok
    MM> {apart from one border case:  swiss[2, , drop = TRUE]  should give a list;
    MM> and that was easy to fix; see the attached dataframe.R-diff
    MM> file which incorporates that fix (and my other cosmetic changes)}

    MM> but running 'make check-all' then shows segmentation faults --- only on one platform of the
    MM> two I've tested {in mgcv's gam() example, boot's  boot()
    MM> example, and I think one other place}

Correction: the problems show on both platforms;

one is in mgcv, gam(), an error in [[ <-  -- pretty clearly linked to your
changes but not reproducible when tried isolatedly
interactively,

the other one is a seg.fault "memory not mapped" when running
the  example
   > nuke.boot <- boot(nuke.data, nuke.fun, R=999, m=1, 
   +      fit.pred=new.fit, x.pred=new.data)


    MM> My guess: typically when dealing with model.frames (which
    MM> internally are "just" data frames with a particular "terms" attribute)
    MM> but the problems are not reproducible when run interactively.
    MM> It may really be that .subset() and .subset2() are sometimes
    MM> used in cases they should not be in your new code; or they even have a bug that
    MM> is not triggered unless by using them in the new context of [.data.frame

    MM> So I'm sorry, but we might have to wait for a "take 3"
    MM> or rather try to find the problem with your patch. 
    MM> Maybe you can try yourself?

    [my diff for dataframe.R]

    MM> Thanks anyway, Vladimir!

    MM> Regards,
    MM> Martin Maechler, ETH Zurich