Merge pull request #352 from gilcu3/Dev

fixing division by zero error in DynBetweenness
networkit · Jun 27, 2019 · 28f34d3 · 28f34d3
2 parents 4a9b9e1 + c0ddf77
commit 28f34d3
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Showing 2 changed files with 83 additions and 6 deletions.
diff --git a/networkit/cpp/centrality/DynBetweenness.cpp b/networkit/cpp/centrality/DynBetweenness.cpp
@@ -142,12 +142,14 @@ void DynBetweenness::decreaseScore(std::vector<bool> & affected, node y, std::pr
 		}
 		G.forNeighborsOf(x, [&](node w, edgeweight weightxw){
 			if (w!= x && (w != v || x != u) && x != y && distancesOld[x][y] == distancesOld[w][y] + weightxw) {
-				if (affected[x]) {
-					// TRACE("Affected node ", x, ". Subtracting from dep of ", w, ": ", sigmaOld[w][y]/sigmaOld[x][y]*(1+dep[x]));
-					dep[w] += sigmaOld[w][y]/sigmaOld[x][y]*(1+dep[x]);
-				} else {
-					// TRACE("Non affected node ", x, ". Subtracting from dep of ", w, ": ", sigmaOld[w][y]/sigmaOld[x][y]*(dep[x]));
-					dep[w] += sigmaOld[w][y]/sigmaOld[x][y]*(dep[x]);
+				if(sigmaOld[x][y] > 0){
+					if (affected[x]) {
+						// TRACE("Affected node ", x, ". Subtracting from dep of ", w, ": ", sigmaOld[w][y]/sigmaOld[x][y]*(1+dep[x]));
+						dep[w] += sigmaOld[w][y]/sigmaOld[x][y]*(1+dep[x]);
+					} else {
+						// TRACE("Non affected node ", x, ". Subtracting from dep of ", w, ": ", sigmaOld[w][y]/sigmaOld[x][y]*(dep[x]));
+						dep[w] += sigmaOld[w][y]/sigmaOld[x][y]*(dep[x]);
+					}
 				}
 				if (! visited[w] && !affected[w] && w != y) {
 					TRACE("Inserting node ", w, " with old priority ", distancesOld[w][y]);

diff --git a/networkit/cpp/centrality/test/DynBetweennessGTest.cpp b/networkit/cpp/centrality/test/DynBetweennessGTest.cpp
@@ -16,6 +16,8 @@
 #include <networkit/graph/Sampling.hpp>
 #include <networkit/generators/DorogovtsevMendesGenerator.hpp>
 #include <networkit/generators/ErdosRenyiGenerator.hpp>
+#include <networkit/centrality/DynBetweenness.hpp>
+#include <networkit/auxiliary/Random.hpp>
 
 namespace NetworKit {
 
@@ -134,5 +136,78 @@ TEST_F(DynBetweennessGTest, runApproxBetweenness) {
 	DEBUG("Number of samples: ", bc1.numberOfSamples());
 }
 
+TEST_F(DynBetweennessGTest, runDynVsStaticCaseInsertDirected){
+	Aux::Random::setSeed(0, false);
+
+	auto genEdgeInsert = [](const Graph& g){
+		node u = g.randomNode();
+		node v = g.randomNode();
+		while (u == v || g.hasEdge(u, v)){
+			u = g.randomNode();
+			v = g.randomNode();
+		}
+		return std::make_pair(u, v);
+	};
+
+	for(count n = 2; n <= 25; n++)
+		for(count t = 0; t < 100; t++){
+			auto g = ErdosRenyiGenerator(n, 0.3, true).generate();
+
+			if(g.numberOfEdges() == g.numberOfNodes() * (g.numberOfNodes() - 1))continue;
+
+			auto e = genEdgeInsert(g);
+			auto ibet = DynBetweenness(g);
+
+			ibet.run();
+
+			auto ne = GraphEvent(GraphEvent::EDGE_ADDITION, e.first, e.second);
+			g.addEdge(e.first, e.second);
+			ibet.update(ne);
+
+			EXPECT_TRUE(g.hasEdge(e.first, e.second));
+			auto brandes = Betweenness(g);
+			brandes.run();
+			g.forNodes([&](node & v){
+				EXPECT_NEAR(brandes.score(v), ibet.score(v), 1e-8);
+			});
+		}
+}
+
+TEST_F(DynBetweennessGTest, runDynVsStaticCaseInsertUndirected){
+	Aux::Random::setSeed(0, false);
+
+	auto genEdgeInsert = [](const Graph& g){
+		node u = g.randomNode();
+		node v = g.randomNode();
+		while (u == v || g.hasEdge(u, v)){
+			u = g.randomNode();
+			v = g.randomNode();
+		}
+		return std::make_pair(u, v);
+	};
+
+	for(count n = 2; n <= 25; n++)
+		for(count t = 0; t < 100; t++){
+			auto g = ErdosRenyiGenerator(n, 0.3, false).generate();
+			if(g.numberOfEdges() == g.numberOfNodes() * (g.numberOfNodes() - 1) / 2)continue;
+
+			auto e = genEdgeInsert(g);
+			auto ibet = DynBetweenness(g);
+
+			ibet.run();
+
+			auto ne = GraphEvent(GraphEvent::EDGE_ADDITION, e.first, e.second);
+			g.addEdge(e.first, e.second);
+			ibet.update(ne);
+			EXPECT_TRUE(g.hasEdge(e.first, e.second));
+
+			auto brandes = Betweenness(g);
+			brandes.run();
+			g.forNodes([&](node & v){
+				EXPECT_NEAR(brandes.score(v), ibet.score(v), 1e-8);
+			});
+		}
+}
+
 
 } /* namespace NetworKit */