Use this if you are using igraph from R
The order of the vertices only matters in directed graphs,
where the existence of a directed
(v1, v2) edge is queried.
are_adjacent(graph, v1, v2)
The first vertex, tail in directed graphs.
The second vertex, head in directed graphs.
A logical scalar,
TRUE is a
(v1, v2) exists in the
Other structural queries:
ug <- make_ring(10) ug are_adjacent(ug, 1, 2) are_adjacent(ug, 2, 1) dg <- make_ring(10, directed = TRUE) dg are_adjacent(ug, 1, 2) are_adjacent(ug, 2, 1)