Check whether a graph is directed

`is_directed(graph)`

graph

The input graph

Logical scalar, whether the graph is directed.

Other structural queries: `[.igraph`

;
`[[.igraph`

; `adjacent_vertices`

;
`are.connected`

, `are_adjacent`

;
`ecount`

, `gsize`

;
`ends`

, `get.edge`

,
`get.edges`

; `get.edge.ids`

;
`gorder`

, `vcount`

;
`head_of`

; `incident_edges`

;
`incident`

; `neighbors`

;
`tail_of`

# NOT RUN { g <- make_ring(10) is_directed(g) g2 <- make_ring(10, directed = TRUE) is_directed(g2) # }