[Rd] [R] data.frame() size

[Gabor Grothendieck]

There was nothing attached in the copy that came through
to me.

By the way, there was some discussion earlier this year
on a light-weight data.frame class but I don't think anyone
ever posted any code.

On 12/9/05, Matthew Dowle <mdowle at concordiafunds.com> wrote:
>
> Hi,
>
> Please see below for post on r-help regarding data.frame() and the
> possibility of dropping rownames, for space and time reasons.
> I've made some changes, attached, and it seems to be working well. I see the
> expected space (90% saved) and time (10 times faster) savings. There are no
> doubt some bugs, and needs more work and testing, but I thought I would post
> first at this stage.
>
> Could some changes along these lines be made to R ? I'm happy to help with
> testing and further work if required. In the meantime I can work with
> overloaded functions which fixes the problems in my case.
>
> Functions effected :
>
>   dim.data.frame
>   format.data.frame
>   print.data.frame
>   data.frame
>   [.data.frame
>   as.matrix.data.frame
>
> Modified source code attached.
>
> Regards,
> Matthew
>
>
> -----Original Message-----
> From: Matthew Dowle
> Sent: 09 December 2005 09:44
> To: 'Peter Dalgaard'
> Cc: 'r-help at stat.math.ethz.ch'
> Subject: RE: [R] data.frame() size
>
>
>
> That explains it. Thanks. I don't need rownames though, as I'll only ever
> use integer subscripts. Is there anyway to drop them, or even better not
> create them in the first place? The memory saved (90%) by not having them
> and 10 times speed up would be very useful. I think I need a data.frame
> rather than a matrix because I have columns of different types in real life.
>
> > rownames(d) = NULL
> Error in "dimnames<-.data.frame"(`*tmp*`, value = list(NULL, c("a", "b" :
>        invalid 'dimnames' given for data frame
>
>
> -----Original Message-----
> From: pd at pubhealth.ku.dk [mailto:pd at pubhealth.ku.dk] On Behalf Of Peter
> Dalgaard
> Sent: 08 December 2005 18:57
> To: Matthew Dowle
> Cc: 'r-help at stat.math.ethz.ch'
> Subject: Re: [R] data.frame() size
>
>
> Matthew Dowle <mdowle at concordiafunds.com> writes:
>
> > Hi,
> >
> > In the example below why is d 10 times bigger than m, according to
> > object.size ? It also takes around 10 times as long to create, which
> > fits with object.size() being truthful.  gcinfo(TRUE) also indicates a
> > great deal more garbage collector activity caused by data.frame() than
> > matrix().
> >
> > $ R --vanilla
> > ....
> > > nr = 1000000
> > > system.time(m<<-matrix(integer(1), nrow=nr, ncol=2))
> > [1] 0.22 0.01 0.23 0.00 0.00
> > > system.time(d<<-data.frame(a=integer(nr), b=integer(nr)))
> > [1] 2.81 0.20 3.01 0.00 0.00                  # 10 times longer
> >
> > > dim(m)
> > [1] 1000000       2
> > > dim(d)
> > [1] 1000000       2                           # same dimensions
> >
> > > storage.mode(m)
> > [1] "integer"
> > > sapply(d, storage.mode)
> >         a         b
> > "integer" "integer"                           # same storage.mode
> >
> > > object.size(m)/1024^2
> > [1] 7.629616
> > > object.size(d)/1024^2
> > [1] 76.29482                                  # but 10 times bigger
> >
> > > sum(sapply(d, object.size))/1024^2
> > [1] 7.629501                                  # or is it ?    If its not
> > really 10 times bigger, why 10 times longer above ?
>
> Row names!!
>
>
> > r <- as.character(1:1e6)
> > object.size(r)
> [1] 72000056
> > object.size(r)/1024^2
> [1] 68.6646
>
> 'nuff said?
>
> --
>   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
>  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
>  (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907
>
>
>
>
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