[R] Apply and its friends

[Ben Bolker]

  As of a recent version (1.7.1?), see ?mapply

  Ben


On Mon, 6 Oct 2003, Thomas W Blackwell wrote:

> Crispin  -
> 
> This is a familiar problem.  The only way I know of to do it is:
> 
> result <- lapply(seq(along=list.a), function(i,a,b) do.it(a[[i]], b[[i]]), list.a, list.b)
> 
> Here,  do.it()  is the function which operates on two elements.
> I use this construction frequently.
> 
> -  tom blackwell  -  u michigan medical school  -  ann arbor  -
> 
> On Mon, 6 Oct 2003, Crispin Miller wrote:
> 
> > I need to take two lists-of-lists, and apply a function to each
> > pair of elements in the lists  to return a single list...
> > For example
> >
> > l1 <- list(1:5,6:10,2:15)
> > l2 <- list(1:8,4:12,1:19,4:20)
> >
> > I could easily do an lapply across each of them, but is there a
> > function that does a sort-of pairwise-apply across both together?
> >
> > Does anybody know of a good document that discusses this kind of
> > basic matrix/list/vector manipulation in R?
> > Regards,
> > crispin
> 
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