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https://issues.apache.org/jira/browse/FLINK-2044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15267211#comment-15267211
]
ASF GitHub Bot commented on FLINK-2044:
---------------------------------------
Github user greghogan commented on a diff in the pull request:
https://github.com/apache/flink/pull/1956#discussion_r61780511
--- Diff:
flink-libraries/flink-gelly/src/main/java/org/apache/flink/graph/library/HITSAlgorithm.java
---
@@ -0,0 +1,194 @@
+/*
+ * 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.aggregators.DoubleSumAggregator;
+import org.apache.flink.api.java.DataSet;
+
+import org.apache.flink.graph.Edge;
+import org.apache.flink.graph.EdgeDirection;
+import org.apache.flink.graph.Graph;
+import org.apache.flink.graph.GraphAlgorithm;
+import org.apache.flink.graph.Vertex;
+import org.apache.flink.graph.spargel.MessageIterator;
+import org.apache.flink.graph.spargel.MessagingFunction;
+import org.apache.flink.graph.spargel.ScatterGatherConfiguration;
+import org.apache.flink.graph.spargel.VertexUpdateFunction;
+import org.apache.flink.types.DoubleValue;
+
+/**
+ * This is an implementation of HITS algorithm, using a scatter-gather
iteration.
+ * The user can define the maximum number of iterations. HITS algorithm is
determined by two parameters,
+ * hubs and authorities. A good hub represented a page that pointed to
many other pages, and a good authority
+ * represented a page that was linked by many different hubs. The
implementation assumes that the two value on
+ * every vertex are the same at the beginning.
+ * <p>
+ * If the number of vertices of the input graph is known, it should be
provided as a parameter
+ * to speed up computation. Otherwise, the algorithm will first execute a
job to count the vertices.
+ */
+public class HITSAlgorithm<K> implements GraphAlgorithm<K, Double, Double,
DataSet<Vertex<K, Double>>> {
+
+ public static enum HITSParameter {
+ HUB,
+ AUTHORITY
+ }
+
+ private int maxIterations;
+ private long numberOfVertices;
+
+ /**
+ * Creates an instance of HITS algorithm.
+ * If the number of vertices of the input graph is known,
+ * use the {@link HITSAlgorithm#HITSAlgorithm(int, long,
HITSParameter)} constructor instead.
+ *
+ * @param maxIterations the maximum number of iterations
+ * @param hitsParameter the type of final web pages users want to get
by this algorithm
+ */
+ public HITSAlgorithm(int maxIterations, HITSParameter hitsParameter) {
+ if (hitsParameter == HITSParameter.AUTHORITY) {
+ this.maxIterations = maxIterations * 2;
+ } else {
+ this.maxIterations = maxIterations * 2 + 1;
+ }
+ }
+
+ /**
+ * Creates an instance of HITS algorithm.
+ * If the number of vertices of the input graph is unknown,
+ * use the {@link HITSAlgorithm#HITSAlgorithm(int, HITSParameter)}
constructor instead.
+ *
+ * @param maxIterations the maximum number of iterations
+ * @param hitsParameter the type of final web pages users want to get
by this algorithm
+ */
+ public HITSAlgorithm(int maxIterations, long numberOfVertices,
HITSParameter hitsParameter) {
+ if (hitsParameter == HITSParameter.AUTHORITY) {
+ this.maxIterations = maxIterations * 2;
+ } else {
+ this.maxIterations = maxIterations * 2 + 1;
+ }
+ this.numberOfVertices = numberOfVertices;
+ }
+
+ @Override
+ public DataSet<Vertex<K, Double>> run(Graph<K, Double, Double>
netGraph) throws Exception {
+ if (this.numberOfVertices == 0) {
+ this.numberOfVertices = netGraph.numberOfVertices();
+ }
+
+ ScatterGatherConfiguration parameter = new
ScatterGatherConfiguration();
+ parameter.setDirection(EdgeDirection.ALL);
+ parameter.registerAggregator("sumAllValue", new
DoubleSumAggregator());
+
+ return netGraph.runScatterGatherIteration(new
VertexUpdate<K>(maxIterations),
+ new MessageUpdate<K>(maxIterations),
maxIterations, parameter).getVertices();
+ }
+
+ /**
+ * Function that updates the value of a vertex by summing up the partial
+ * values from all messages and normalize the value.
+ */
+ @SuppressWarnings("serial")
+ public static final class VertexUpdate<K> extends
VertexUpdateFunction<K, Double, Double> {
+ private int maxIteration;
+ private DoubleSumAggregator doubleSumAggregator;
+
+ public VertexUpdate(int maxIteration) {
+ this.maxIteration = maxIteration;
+ }
+
+ @Override
+ public void preSuperstep() {
+ doubleSumAggregator =
getIterationAggregator("sumAllValue");
+ }
+
+ @Override
+ public void updateVertex(Vertex<K, Double> vertex,
MessageIterator<Double> inMessages) {
+ double updateValue = 0;
+
+ for (double element : inMessages) {
+ if (getSuperstepNumber() == maxIteration) {
+ updateValue = element;
+ break;
+ }
+ updateValue += element;
+ }
+
+ if (getSuperstepNumber() != maxIteration) {
+ setNewVertexValue(updateValue);
+ doubleSumAggregator.aggregate(updateValue);
+ } else {
+ setNewVertexValue(vertex.getValue() /
updateValue);
+ }
+ }
+ }
+
+ /**
+ * Distributes the value of a vertex among all neighbor vertices and
sum all the
+ * value in every superstep.
+ */
+ @SuppressWarnings("serial")
+ public static final class MessageUpdate<K> extends MessagingFunction<K,
Double, Double, Double> {
+ private int maxIteration;
+
+ public MessageUpdate(int maxIteration) {
+ this.maxIteration = maxIteration;
+ }
+
+ @Override
+ public void sendMessages(Vertex<K, Double> vertex) {
+ for (Edge<K, Double> edge : getEdges()) {
+ if (getSuperstepNumber() % 2 == 1) {
--- End diff --
The only difference between the if and else is the flipping of source and
target, so this could be condensed.
> Implementation of Gelly HITS Algorithm
> --------------------------------------
>
> Key: FLINK-2044
> URL: https://issues.apache.org/jira/browse/FLINK-2044
> Project: Flink
> Issue Type: New Feature
> Components: Gelly
> Reporter: Ahamd Javid
> Assignee: GaoLun
> Priority: Minor
>
> Implementation of Hits Algorithm in Gelly API using Java. the feature branch
> can be found here: (https://github.com/JavidMayar/flink/commits/HITS)
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