format_index_ids is deprecated and will be removed in a future release.
format_index_ids(g, return_list = FALSE)list containing an adjacency matrix and a lengths vector indicating
the number of connections from each node. If return_list is TRUE, return
will also include a data.frame with an indid column and a toindid list
column.
data.frame graph with id, inid and toindid as returned by make_index_ids
logical if TRUE, the returned list will include a "froms_list" element containing all from ids in a list form.