Function degree_closeness_correlation 

pub fn degree_closeness_correlation(graph: &Graph) -> IgraphResult<f64>

Compute the degree-closeness correlation.

Pearson correlation between vertex degree and closeness centrality (reciprocal of mean distance). Returns 0.0 for disconnected or trivial graphs, or when degree or closeness has zero variance.

Examples

use rust_igraph::{Graph, degree_closeness_correlation};

// K_3: constant degree and closeness → 0.0
let g = Graph::from_edges(&[(0,1),(1,2),(0,2)], false, Some(3)).unwrap();
assert!(degree_closeness_correlation(&g).unwrap().abs() < 1e-10);