for (i = 0; i < nedges; i++){
char *edge_str = NULL, edge_id[200], node_source[200], node_target[200];
read = getline (&edge_str, &size, file);
for (i = 0; i < nedges; i++){
char *edge_str = NULL, edge_id[200], node_source[200], node_target[200];
read = getline (&edge_str, &size, file);