[R] converting lists got by tapply to dataframes

[Liaw, Andy]

That gives you a vector, not a data frame.

The problem is that the object returned by tapply is a 1-d array of list.
When as.data.frame() is called, the default method doesn't know how to
handle arrays and gives the error.  What you really want for this particular
case is to treat the object as a list, so the unorthodox way is:

  as.data.frame.list(xb)

OK, I didn't really say that...

Andy

> From: Andrew Robinson
> 
> Wolfram,
> 
> try 
> 
> unlist(xb) 
> 
> Andrew
> 
> On Wednesday 10 March 2004 06:58, Wolfram Fischer wrote:
> > I have two lists:
> >
> >     xa <- list( X=c(1,2,3), Y=c(4,5,6), Z=c(7,8,9) )
> >
> >     xb <- with( barley, tapply( X=seq(1:nrow(barley)), INDEX=site
> >         , FUN=function(z)yield[z]))
> >
> > I can convert xa to a dataframe easily with:
> >     as.data.frame(xa)
> >
> > But if i try the same with xb I get:
> >     as.data.frame(xb)
> >     Error in as.data.frame.default(xb) :
> >     can't coerce array into a data.frame
> >
> > What helps?
> >
> > (NB: I know the formula for xb is stupid, but it generates the same
> > type of list as the list I get from my real problem.)
> >
> > Wolfram
> >
> > ______________________________________________
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> 
> -- 
> Andrew Robinson                      Ph: 208 885 7115
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