Method subgraph

nodedb-graph/src/traversal.rs:302–342

Materialize a subgraph as edge tuples within max_depth. `max_visited` caps the number of nodes visited to prevent supernode fan-out explosion. Pass [`DEFAULT_MAX_VISITED`] for the standard limit.

(
        &self,
        start_nodes: &[&str],
        label_filter: Option<&str>,
        max_depth: usize,
        max_visited: usize,
    )

    /// `max_visited` caps the number of nodes visited to prevent supernode fan-out
    /// explosion. Pass [`DEFAULT_MAX_VISITED`] for the standard limit.
    pub fn subgraph(
        &self,
        start_nodes: &[&str],
        label_filter: Option<&str>,
        max_depth: usize,
        max_visited: usize,
    ) -> Vec<(String, String, String)> {
        let label_id = label_filter.and_then(|l| self.label_id(l));
        let mut visited: HashSet<u32> = HashSet::new();
        let mut queue: VecDeque<(u32, usize)> = VecDeque::new();
        let mut edges = Vec::new();

        for &node in start_nodes {
            if let Some(&id) = self.node_to_id.get(node)
                && visited.insert(id)
            {
                queue.push_back((id, 0));
            }
        }

        while let Some((node_id, depth)) = queue.pop_front() {
            if depth >= max_depth || visited.len() >= max_visited {
                continue;
            }
            self.record_access(node_id);
            for (lid, dst) in self.dense_iter_out(node_id) {
                if label_id.is_none_or(|f| f == lid) {
                    edges.push((
                        self.id_to_node[node_id as usize].clone(),
                        self.label_name(lid).to_string(),
                        self.id_to_node[dst as usize].clone(),
                    ));
                    if visited.len() < max_visited && visited.insert(dst) {
                        queue.push_back((dst, depth + 1));
                    }
                }
            }
        }

        edges
    }
}

#[cfg(test)]