Function count_loops 

pub fn count_loops(graph: &Graph) -> IgraphResult<usize>

Counts self-loop edges in graph.

A self-loop is an edge (v, v). Returns the total number of such edges, counting parallel self-loops separately.

Counterpart of igraph_count_loops() from references/igraph/src/properties/loops.c.

O(|E|) linear scan.

Examples

use rust_igraph::{Graph, count_loops};

let mut g = Graph::with_vertices(3);
g.add_edge(0, 1).unwrap();
g.add_edge(1, 1).unwrap();
g.add_edge(2, 2).unwrap();
g.add_edge(2, 2).unwrap();
assert_eq!(count_loops(&g).unwrap(), 3);