fix closeness distance: 1 extra length is calculated (#67)

Change-Id: I35bc20698bf93002a530b95688cd0359a9154fdf
apache · Nov 7, 2022 · 6d19a9e · 6d19a9e
1 parent a6fbb7c
commit 6d19a9e
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/...re/src/main/java/com/baidu/hugegraph/job/algorithm/cent/ClosenessCentralityAlgorithm.java b/...re/src/main/java/com/baidu/hugegraph/job/algorithm/cent/ClosenessCentralityAlgorithm.java
@@ -89,10 +89,17 @@ public Object closenessCentrality(Directions direction,
             t = t.emit().until(__.loops().is(P.gte(depth)));
             t = filterNonShortestPath(t, true);
 
+            /*
+             * We use Marchiori's algorithm(sum of reciprocal of distances):
+             *  .math("_-1").sack(Operator.div).sack().sum()
+             * for Bavelas's algorithm:
+             *  .math("_-1").sum().sack(Operator.div).sack()
+             * see https://en.wikipedia.org/wiki/Closeness_centrality
+             */
             GraphTraversal<Vertex, ?> tg;
             tg = t.group().by(__.select(Pop.first, "v").id())
                           .by(__.select(Pop.all, "v").count(Scope.local)
-                                .sack(Operator.div).sack().sum());
+                                .math("_-1").sack(Operator.div).sack().sum());
             GraphTraversal<Vertex, ?> tLimit = topN(tg, topN);
 
             return this.execute(tLimit, () -> tLimit.next());