# Re: [R] Re-sort list of vectors

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Tue 16 Aug 2005 - 03:18:05 EST

You could try using one of the sparse representations of matrices in the SparseM or Matrix packages. Both packages have vignettes.

Andy

> From: Jan Hummel
>
> Thanks a lot! But unfortunately I will not know the
> dimensions of both lists. And further, the lists may be
> (partly) disjoint as: x <- list("1"=c(a=1, b=2, c=3),
> "2"=c(d=4, b=5, e=6)). And last but not least I'm really have
> to have access to the names of the named list items.
>
> The problem I dealt with is in unlist() merging the names
> together, as you can see in your example given: "V1", "V2"
> and "V3". Because off interpreting the names later as
> identifiers in db queries I'm really interested in getting
> something like list("a"=c("1"=1), "b"=c("1"=2, "2"=5),
> "c"=c("1"=3), "d"=c("1"=4), "e"=c("1"=6)) for the above input.
> By giving the result this way I'm able to extract both names
> from two sets as well as the according value between both items.
>
> One point could be to build a matrix but this matrix would
> have many NA's. So I prefer Lists of Lists.
>
> Any ideas?
>
> cheers
> Jan
>
> -----Ursprüngliche Nachricht-----
> Von: Liaw, Andy [mailto:andy_liaw@merck.com]
> Gesendet: Montag, 15. August 2005 17:31
> An: Jan Hummel; r-help@stat.math.ethz.ch
> Betreff: RE: [R] Re-sort list of vectors
>
> If all vectors in the list have the same length, why not use
> a matrix? Then you'd just transpose the matrix if you need
> to. If you really have to have it as a list, here's one possibility:
>
> > x <- list("1"=c(a=1, b=2, c=3), "2"=c(a=4, b=5, c=6)) x
> \$"1"
> a b c
> 1 2 3
>
> \$"2"
> a b c
> 4 5 6
> > as.list(as.data.frame(t(matrix(unlist(x), nrow=3))))
> \$V1
> [1] 1 4
>
> \$V2
> [1] 2 5
>
> \$V3
> [1] 3 6
>
> Andy
>
>
> > From: Jan Hummel
> >
> > Hi.
> > Can anyone suggest a simple way to re-sort in R a list of
> vectors of
> > the following form?
> >
> > input
> > \$"1"
> > a b c
> > 1 2 3
> > \$"2"
> > a b c
> > 4 5 6
> >
> > Output should be something like:
> > "a"
> > "1" 1
> > "2" 4
> > "b"
> > "1" 2
> > "2" 5
> > "c"
> > "1" 3
> > "2" 6
> >
> > I've been futzing with mapply(), outer(), split(), rbind()
> and so on
> > but haven't found an elegant solution.
> >
> > Thanks,
> > Jan.
> >
> > P.S. E-mailed CCs of posted replies appreciated.
> >
> > ______________________________________________
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> >
> >
> >
>
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