transpose nested list

Question

I have a list structure which represents a table being handed to me like this

> l = list(list(1, 4), list(2, 5), list(3, 6))
> str(l)
List of 3
 $ :Lis         


        

Answer 1

For the specific example, you can use this pretty simple approach:

split(unlist(l), c("x", "y"))
#$x
#[1] 1 2 3
#
#$y
#[1] 4 5 6

It recycles the x-y vector and splits on that.

---

To generalize this to "n" elements in each list, you can use:

l = list(list(1, 4, 5), list(2, 5, 5), list(3, 6, 5)) # larger test case

split(unlist(l, use.names = FALSE), paste0("x", seq_len(length(l[[1L]]))))
# $x1
# [1] 1 2 3
# 
# $x2
# [1] 4 5 6
# 
# $x3
# [1] 5 5 5

This assumes, that all the list elements on the top-level of l have the same length, as in your example.