unlisting a list while keeping the indices

Question

I have a list which can have either empty entries, entries containing one elements and entries containing multiple elements.

l1 = list(integer(0), 11L, integer(         


        

Answer 1

We can have two options. Make the list a named one, enframe it to a tbl_df and then unnest the list element. The NULL elements will be automatically removed

library(tidyverse)
l1 %>% 
     set_names(seq_along(.)) %>% 
     enframe %>%
     unnest

Or after naming the list, stack it to a 2 column data.frame

stack(setNames(l1, seq_along(l1)))[2:1]