Function run

nodedb/src/engine/graph/algo/harmonic.rs:20–41

Run Harmonic Centrality on the CSR index. Returns `(node_id, centrality)` sorted by centrality descending.

(csr: &CsrIndex)

///
/// Returns `(node_id, centrality)` sorted by centrality descending.
pub fn run(csr: &CsrIndex) -> AlgoResultBatch {
    let n = csr.node_count();
    if n == 0 {
        return AlgoResultBatch::new(GraphAlgorithm::Harmonic);
    }

    let normalizer = if n > 1 { (n - 1) as f64 } else { 1.0 };
    let mut scored: Vec<(usize, f64)> = Vec::with_capacity(n);

    for v in 0..n {
        let inv_sum = bfs_inverse_distances(csr, v as u32, n);
        scored.push((v, inv_sum / normalizer));
    }

    scored.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

    let mut batch = AlgoResultBatch::new(GraphAlgorithm::Harmonic);
    for (node, centrality) in scored {
        batch.push_node_f64(csr.node_name_raw(node as u32).to_string(), centrality);
    }
    batch
}

/// BFS from source, return sum of 1/d(source, u) for all reachable u.
fn bfs_inverse_distances(csr: &CsrIndex, source: u32, n: usize) -> f64 {