[R] Unlisting while preserving object types?

Turner, Jason Jason.Turner at chh.co.nz
Wed Oct 10 00:42:06 CEST 2001


Thanks Jake, 

The example I gave is a toy one, however, and I neglected to mention that I
need it
automated because the number of members (in the example, a and b) isn't
known in 
advance, and could typically be as high as 30.  I got tired of typing it all
out each time.
Sorry I forgot the most crucial details - I keep forgetting that the whole
world isn't
working on this with me.  ;-)

Cheers

Jason

> Hi Jason,
> 
> How about this:
> 
> zz.spec<-lapply(zz,FUN=function(x){
> spectrum(x,plot=F)
> })
> 
> yourmatrix<-cbind(zz.spec$a$spec,zz.spec$b$spec)
> 
> Best,
> Jake
> 
> On Wed, 10 Oct 2001, Turner, Jason wrote:
> 
> > Hi
> > 
> > A toy example is probably the least ambiguous way of explaining what I'm
> > trying to do.
> > 
> > > library(ts)
> > > zz<-list(a=rnorm(100),b=rt(100,3))
> > > zz.spec<-lapply(zz,spectrum,plot=F)
> > > summary(zz.spec)
> >   Length Class Mode
> > a 15     spec  list
> > b 15     spec  list
> > 
> > I'm looking for an elegant way to fetch components of the sub-lists a
> and b
> > of zz.spec; 
> > e.g. to make a matrix with columns a$spec and b$spec.  
> > 
> >
> matrix(unlist(lapply(zz.spec,function(x){return(x$spec)})),ncol=length(zz.
> sp
> > ec))
> > 
> > is about the best I've come up with.  Is there a more direct way?  This
> gets
> > particularly
> > important with nested sub-lists - lists of lists of lists.  Is the best
> > approach is to 
> > have the good sense to avoid such structures in the first place?
> > 
> > Cheers
> > 
> > Jason
> > 
> > 

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