Re: [R] reshaping data.frame question

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Tue 27 Jun 2006 - 22:27:34 EST


You might want to try the Oarray package on CRAN.

Andy

From: Matthias Braeunig
>
> Thanks, this is not what what I meant. I need to reshape the
> original dataframe that I can access p_f[X] for numerical X.
> Maybe I was not clear enough.
>
> The problem really is that X starts at 0. Note that in my
> example changing the row names to 0:2 does not have the
> desired effect.
>
>
>
> jim holtman wrote:
> > You need to specify the row/column name as character:
> >
> >> y
> > X1 X2 X3 X4
> > 0 0.1 0.1 0.1 0.1
> > 1 0.2 0.2 0.2 0.2
> > 2 0.3 0.3 0.3 0.3
> >
> >> y[,'X3']
> > [1] 0.1 0.2 0.3
> >> y['0','X3']
> > [1] 0.1
> >
> >
> >
> >
> > On 6/26/06, Matthias Braeunig <mb.atelier@web.de> wrote:
> >>
> > Dear R-helpers,
> >
> >
> > my data.frame is of the form
> >
> > x <- data.frame( f=gl(4,3), X=rep(0:2,4), p=c(.1,.2,.3)) x
> > f X p
> > 1 1 0 0.1
> > 2 1 1 0.2
> > 3 1 2 0.3
> > 4 2 0 0.1
> > 5 2 1 0.2
> > 6 2 2 0.3
> > 7 3 0 0.1
> > 8 3 1 0.2
> > 9 3 2 0.3
> > 10 4 0 0.1
> > 11 4 1 0.2
> > 12 4 2 0.3
> >
> > which tabulates some values p(X) for several factors f.
> >
> > Now I want to put it in "wide" format, so that factor
> levels appear as
> > column heads. Note also that X starts from zero. It would
> be nice if I
> > could simply access p_f[X==0] as f[0]. How can I possibly do that?
> >
> > (The resilting object does not have to be a data.frame. As
> there are
> > only numeric values, also a matrix would do.)
> >
> > I tried the following
> >
> > y<-unstack(x,form=p~f)
> > row.names(y) <- 0:2
> > y
> > X1 X2 X3 X4
> > 0 0.1 0.1 0.1 0.1
> > 1 0.2 0.2 0.2 0.2
> > 2 0.3 0.3 0.3 0.3
> >
> > Now, how to access X3[0], say?
> >
> > Maybe reshape would be the right tool, but I could not
> figure it out.
> >
> > I appreciate your help. Thanks!
>
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