[R] dimensions of a all objects
Gabor Grothendieck
ggrothendieck at gmail.com
Tue Jan 9 16:38:35 CET 2007
See below.
On 1/9/07, Farrel Buchinsky <fjbuch at gmail.com> wrote:
> You have assumed everything as I meant it.
> I understand what is happening now. ls() simply creates a vector with
> character elements and dim() sees each element as not having dimensions. The
> critical part of what you have shown is the get(command) that turns what is
> just a string into the dataframe or vector whose name is the string. The
> other issue which you showed, and one that I have come across before is that
> sapply and tapply and lapply cannot handle a function on a function. I would
> have thought that I should get the same result from
>
> lapply(ls(),dim(get())) or something such as that.
The gsubfn package can do nearly that. Just preface the function
of interest (in this case sapply) with fn$ and then you can
write the function as a formula:
> library(gsubfn)
> fn$sapply(c("iris", "CO2"), ~ dim(get(x)), simplify = FALSE)
$iris
[1] 150 5
$CO2
[1] 84 5
>
> But instead one has to create a function command within the lapply to handle
> a dimension command upon a get command.
>
>
> On 1/9/07, Barry Rowlingson <b.rowlingson at lancaster.ac.uk> wrote:
> >
> > Farrel Buchinsky wrote:
> > > Why will the following command not work
> > > sapply(objects(),dim)
> > > What does it say about the objects list? What does it say about the dim
> > > command?
> > >
> > > Likewise, the following also does not work
> > > all<-ls()
> > > for (f in all) print(dim(f))
> >
> > 'objects()' returns character strings - the names of objects - then
> > the dim of the character strings are all NULL.
> >
> > I'll assume that's what you are getting at - you've not posted an
> > example or the output you are getting or why it 'does not work'.
> >
> > Maybe you want this:
> > > sapply(objects(),function(x){dim(get(x))})
> > $f
> > NULL
> >
> > $m
> > [1] 2 5
> >
> > $x
> > NULL
> >
> > $y
> > [1] 5 2
> >
> > - where m and y are matrices, f is a function, x is a scalar.
> >
> > Barry
> >
> >
>
>
> --
> Farrel Buchinsky
> Mobile: (412) 779-1073
>
> [[alternative HTML version deleted]]
>
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