[R] Creating a list from all combinations of two lists

[Jim Lemon]

On 11/22/2011 06:31 AM, Jonathan Greenberg wrote:
> R-helpers:
>
> Say I have two lists of arbitrary elements, e.g.:
>
>   list1=list(c(1:3),"R is fun!",c(3:6))
>
> list2=list(c(10:5),c(5:3),c(13,5),"I am so confused")
>
>
> I would like to produce a single new list that is composed of all
> combinations of the "top level" of list1 and list2, e.g.:
>
> listcombo=list(list(list1[[1]],list2[[1]]),list(list1[[1]],list2[[2]]
> ),...,list(list1[[length(list1)]],list2[[length(list2]]))
>
> What is the most efficient way to do this?  Thanks!
>
Hi Jonathan,
The makeIntersectList function (plotrix) does this for the attribute 
labels that represent the top level sets. However, it assumes that the 
attribute labels are character variables. You may be able to generalize 
the code to handle arbitrary objects.

Jim