Function are_adjacent 

pub fn are_adjacent(
    graph: &Graph,
    v1: VertexId,
    v2: VertexId,
) -> IgraphResult<bool>

Check whether two vertices are connected by at least one edge.

For directed graphs, checks if there is an edge from v1 to v2 or from v2 to v1 (i.e. direction is ignored, matching the C implementation which uses IGRAPH_DIRECTED but still checks adjacency in both directions for undirected queries).

Errors

• Returns an error if either v1 or v2 is out of range.

Examples

use rust_igraph::{Graph, are_adjacent};

let mut g = Graph::with_vertices(4);
g.add_edge(0, 1).unwrap();
g.add_edge(2, 3).unwrap();

assert!(are_adjacent(&g, 0, 1).unwrap());
assert!(!are_adjacent(&g, 0, 2).unwrap());