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degree_sequence_game_vl

rust_igraph::algorithms::games::degree_sequence_vl

Function degree_sequence_game_vl 

Source 
pub fn degree_sequence_game_vl(
    degrees: &[u32],
    seed: u64,
) -> IgraphResult<Graph>
Expand description

Sample a random connected, simple undirected graph that exactly realises the given degree sequence, approximately uniformly, via the Viger–Latapy edge-switch Markov chain.

  • degrees — undirected degree of every vertex. Length defines vertex count n.
  • seed — drives the internal SplitMix64 PRNG.

§Errors

  • Vertex count exceeds u32::MAX.
  • Edge count Σd / 2 exceeds u32::MAX.
  • Degree sum overflows u64.
  • Degree sequence is not graphical (sum is odd, or fails Erdős–Gallai), or any single degree exceeds n - 1.
  • Sequence is graphical but cannot be realized as a connected simple graph — e.g. it contains a 0 degree on more than one vertex while the rest demand a single component.

§Examples

use rust_igraph::degree_sequence_game_vl;

// 4-cycle: every vertex degree 2 ⇒ 4 edges total, connected.
let g = degree_sequence_game_vl(&[2, 2, 2, 2], 7).unwrap();
assert_eq!(g.vcount(), 4);
assert_eq!(g.ecount(), 4);
assert!(!g.is_directed());