Github user vasia commented on a diff in the pull request:
https://github.com/apache/flink/pull/1054#discussion_r37869769
--- Diff:
flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/library/GSATriangleCount.java
---
@@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.graph.library;
+
+
+import org.apache.flink.api.common.functions.MapFunction;
+import org.apache.flink.api.common.functions.ReduceFunction;
+import org.apache.flink.api.java.DataSet;
+import org.apache.flink.api.java.ExecutionEnvironment;
+import org.apache.flink.api.java.tuple.Tuple1;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.graph.GraphAlgorithm;
+import org.apache.flink.graph.ReduceNeighborsFunction;
+import org.apache.flink.graph.Vertex;
+import org.apache.flink.graph.Edge;
+import org.apache.flink.graph.Triplet;
+import org.apache.flink.graph.EdgeDirection;
+import org.apache.flink.graph.Graph;
+import org.apache.flink.types.NullValue;
+
+import java.util.TreeMap;
+
+/**
+ * Triangle Count Algorithm.
+ *
+ * This algorithm operates in three phases. First, vertices select
neighbors with id greater than theirs
+ * and send messages to them. Each received message is then propagated to
neighbors with higher id.
+ * Finally, if a node encounters the target id in the list of received
messages, it increments the number
+ * of triangles found.
+ *
+ * This implementation is non - iterative. The total number of triangles
can be determined by performing
+ * a single pass through the graph.
+ */
+public class GSATriangleCount implements
+ GraphAlgorithm<Long, NullValue, NullValue,
DataSet<Tuple1<Integer>>> {
+
+ @Override
+ public DataSet<Tuple1<Integer>> run(Graph<Long, NullValue, NullValue>
input) throws Exception {
+
+ ExecutionEnvironment env = input.getContext();
+
+ // order the edges so that src is always higher than trg
+ DataSet<Edge<Long, NullValue>> edges = input.getEdges()
+ .map(new OrderEdges()).distinct();
--- End diff --
this call to `distinct()` here means that basically if you have 2 edges
a->b and b->a in the input, and they are both part of a triangle, then you only
count it once?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
