For undirected graphs, head and tail is not defined. In this case
tail_of()
returns vertices incident to the supplied edges, and
head_of()
returns the other end(s) of the edge(s).
See also
Other structural queries:
[.igraph()
,
[[.igraph()
,
adjacent_vertices()
,
are_adjacent()
,
ends()
,
get.edge.ids()
,
gorder()
,
gsize()
,
head_of()
,
incident()
,
incident_edges()
,
is_directed()
,
neighbors()