[igraph] data presentation prob

[Ragia Ibrahim]

Hi,
 I got data like the following  taken from a graph

id          reacableh_list                  number of reachable
  ---------------------------------------------------
  1             1 4                                          2
  2             2 3 4                                         3
 3               3 2 1                                        3 
 4               4                                              1
----------------------------------------------------------


i couldn't put it in data frame since the reachable list is not the same?
i want to keep it ..be able to sort..and get intersection and union between reachable lists..
any suggestions please




Ragia.