Function build_personalization

nodedb/src/engine/graph/algo/pagerank.rs:126–144

Build the normalized per-node seed distribution for Personalized PageRank. Returns `None` (→ standard uniform PageRank) when no personalization vector is supplied, or when none of its seed nodes exist in the graph / all seed weights are non-positive — falling back to uniform rather than emitting an all-zero ranking. Negative weights are clamped to 0.0. The returned vector is indexed by CSR node o

(csr: &CsrIndex, params: &AlgoParams, n: usize)

/// all-zero ranking. Negative weights are clamped to 0.0. The returned vector
/// is indexed by CSR node ordinal and sums to 1.0.
fn build_personalization(csr: &CsrIndex, params: &AlgoParams, n: usize) -> Option<Vec<f64>> {
    let seeds = params.personalization_vector()?;
    let mut p = vec![0.0f64; n];
    let mut sum = 0.0;
    for (i, slot) in p.iter_mut().enumerate() {
        if let Some(&w) = seeds.get(csr.node_name_raw(i as u32)) {
            let w = w.max(0.0);
            *slot = w;
            sum += w;
        }
    }
    if sum <= 0.0 {
        return None;
    }
    for v in &mut p {
        *v /= sum;
    }
    Some(p)
}

#[cfg(test)]
mod tests {