How to construct an edge list from data in R? -

i have data looks this:

+--------+-----------+ | source |  targets  | +--------+-----------+ |      1 |   3, 4, 5 | |      2 |      1, 3 | |      3 | 6, 10, 11 | +--------+-----------+ 

where source node in graph data, , targets list of target nodes, i.e. there's connection node 1 3, 4, d 5 nodes. want create edges list, so:

+------+----+ | | | +------+----+ |    1 |  3 | |    1 |  4 | |    1 |  5 | +------+----+ 

but i'm having trouble getting done in r. best i've been able yet following:

extract_edges <- function(row) {   targets <- strsplit(as.character(locke_relations[row, 3]), ", ")   df <- data.frame()   for(t in targets) {     newrow <- data.frame(from=locke_relations[row,1], to=t)     df <- rbind(df, newrow)   }   df } lapply((2:3), extract_edges) 

locke_relations above data more or less in form above, , in code above, processing 2 rows (rows 2 & 3). gets me list containing dataframes more or less corrrect:

[[1]]       1 47678 48378 2 47678 48379  [[2]]       1 47686 47804 2 47686 49326 

but want here is:

      1 47678 48378 2 47678 48379 3 47686 47804 4 47686 49326 

i try find way merge list feel whole approach here off , in r there more efficient way this. know how best way in r?

you can use separate_rows tidyr:

tidyr::separate_rows(df, targets)  #  source target #1      1      3 #2      1      4 #3      1      5 #4      2      1 #5      2      3 #6      3      6 #7      3     10 #8      3     11