list - Determine level of nesting in R?

Question

Is there an easy way (i.e. a function) to determine the level of nesting in list? I know there is str which can be used to get this information. But is there something that simply gives back the result? And can I use such a function to get the names of all levels of alist (recursively) ?

Answer 1

A little recursive function can do this for you:

depth <- function(this,thisdepth=0){
  if(!is.list(this)){
    return(thisdepth)
  }else{
    return(max(unlist(lapply(this,depth,thisdepth=thisdepth+1))))    
  }
}

If you've got package:testthat, here's a test set:

l1=list(1,2,3)
l2=list(1,2,l1,4)
l3=list(1,l1,l2,5)

require(testthat)
expect_equal(depth(l1),1)
expect_equal(depth(l2),2)
expect_equal(depth(l3),3)

Apologies for using lower-case L in variable names. Readability fail.