Use this if you are using igraph from R
For undirected graphs, head and tail is not defined. In this case
head_of returns vertices incident to the supplied edges, and
tail_of returns the other end(s) of the edge(s).
head_of(graph, es)
graph |
The input graph. |
es |
The edges to query. |
A vertex sequence with the head(s) of the edge(s).
Other structural queries: [.igraph,
[[.igraph, adjacent_vertices,
are_adjacent, ends,
get.edge.ids, gorder,
gsize, incident_edges,
incident, is_directed,
neighbors, tail_of