[R] reshaping data.frame question

[Liaw, Andy]

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 at 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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