pub fn efficiency(graph: &Graph, source: &str, target: &str) -> Option<f64>Expand description
Compute the efficiency of a pair of distinct nodes.
Efficiency is the reciprocal of the unweighted shortest-path distance.
Returns 0.0 when no path exists and None when both node arguments are
the same, allowing the Python binding to mirror NetworkX’s
ZeroDivisionError behavior for efficiency(G, u, u).