Function join 

pub fn join(left: &Graph, right: &Graph) -> IgraphResult<Graph>

Creates the join of two graphs.

The join first takes the disjoint union of left and right, then adds all edges between the vertices originating from left and those from right. This produces a graph with |V1| + |V2| vertices and |E1| + |E2| + |V1|*|V2| edges (for undirected), or |E1| + |E2| + 2*|V1|*|V2| edges (for directed, since both directions are added).

Both graphs must have the same directedness.

Arguments

• left — the first graph.
• right — the second graph.

Errors

Returns InvalidArgument if the graphs differ in directedness.

Examples

use rust_igraph::{Graph, join};

let g1 = Graph::with_vertices(2); // 2 isolated vertices
let g2 = Graph::with_vertices(3); // 3 isolated vertices

let j = join(&g1, &g2).unwrap();
assert_eq!(j.vcount(), 5);
// 0 original edges + 2*3 = 6 cross-edges
assert_eq!(j.ecount(), 6);