# are_adjacent

From igraph v1.0.1
by Gabor Csardi

##### Are two vertices adjacent?

The order of the vertices only matters in directed graphs,
where the existence of a directed `(v1, v2)`

edge is queried.

##### Usage

`are_adjacent(graph, v1, v2)`

##### Arguments

- graph
The graph.

- v1
The first vertex, tail in directed graphs.

- v2
The second vertex, head in directed graphs.

##### Value

A logical scalar, `TRUE`

is a `(v1, v2)`

exists in the
graph.

##### See Also

Other structural queries: `[.igraph`

;
`[[.igraph`

; `adjacent_vertices`

;
`ecount`

, `gsize`

;
`ends`

, `get.edge`

,
`get.edges`

; `get.edge.ids`

;
`gorder`

, `vcount`

;
`head_of`

; `incident_edges`

;
`incident`

; `is.directed`

,
`is_directed`

; `neighbors`

;
`tail_of`

##### Examples

```
# NOT RUN {
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)
# }
```

*Documentation reproduced from package igraph, version 1.0.1, License: GPL (>= 2)*

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