Function get_shortest_path 

pub fn get_shortest_path(
    graph: &Graph,
    from: VertexId,
    to: VertexId,
    weights: Option<&[f64]>,
    mode: DijkstraMode,
) -> IgraphResult<ShortestPath>

Calculate a single shortest path from from to to.

Returns the path as both its vertex sequence (source first, target last) and the edge sequence along it. If several shortest paths exist, an arbitrary one is returned.

The backend mirrors igraph_get_shortest_paths:

• weights == None: unweighted breadth-first search,
• weights == Some(w) with all w[e] >= 0: Dijkstra,
• weights == Some(w) with any w[e] < 0: Bellman-Ford.

On directed graphs mode selects which adjacency is followed (DijkstraMode::Out / DijkstraMode::In / DijkstraMode::All); it is ignored on undirected graphs.

Errors

Returns IgraphError::VertexOutOfRange if from or to is not a valid vertex, or IgraphError::InvalidArgument if weights is provided and its length differs from the edge count or contains NaN.

Examples

use rust_igraph::{Graph, get_shortest_path, DijkstraMode};

let mut g = Graph::new(4, false).unwrap();
g.add_edge(0, 1).unwrap(); // edge 0
g.add_edge(1, 2).unwrap(); // edge 1
g.add_edge(2, 3).unwrap(); // edge 2
let p = get_shortest_path(&g, 0, 3, None, DijkstraMode::Out).unwrap();
assert_eq!(p.vertices, vec![0, 1, 2, 3]);
assert_eq!(p.edges, vec![0, 1, 2]);

// Unreachable target → empty path.
let mut h = Graph::new(2, true).unwrap();
h.add_edge(0, 1).unwrap();
let q = get_shortest_path(&h, 1, 0, None, DijkstraMode::Out).unwrap();
assert!(q.vertices.is_empty());
assert!(q.edges.is_empty());