Github user andralungu commented on a diff in the pull request:
https://github.com/apache/flink/pull/408#discussion_r25852832
--- Diff:
flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/example/GSAGreedyGraphColoringExample.java
---
@@ -0,0 +1,212 @@
+/*
+ * 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.example;
+
+import org.apache.flink.api.common.ProgramDescription;
+import org.apache.flink.api.common.functions.MapFunction;
+import org.apache.flink.api.java.DataSet;
+import org.apache.flink.api.java.ExecutionEnvironment;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.tuple.Tuple3;
+import org.apache.flink.graph.Edge;
+import org.apache.flink.graph.Graph;
+import org.apache.flink.graph.Vertex;
+import org.apache.flink.graph.example.utils.ExampleUtils;
+import org.apache.flink.graph.gsa.ApplyFunction;
+import org.apache.flink.graph.gsa.GatherFunction;
+import org.apache.flink.graph.gsa.GatherSumApplyIteration;
+import org.apache.flink.graph.gsa.SumFunction;
+import org.apache.flink.graph.gsa.Triplet;
+
+import java.util.HashSet;
+
+/**
+ * This is an implementation of the Greedy Graph Coloring algorithm, using
a gather-sum-apply iteration
+ */
+public class GSAGreedyGraphColoringExample implements ProgramDescription {
+
+ //
--------------------------------------------------------------------------------------------
+ // Program
+ //
--------------------------------------------------------------------------------------------
+
+ public static void main(String[] args) throws Exception {
+
+ if (!parseParameters(args)) {
+ return;
+ }
+
+ ExecutionEnvironment env =
ExecutionEnvironment.getExecutionEnvironment();
+
+ DataSet<Vertex<Long, Double>> vertices = getVertexDataSet(env);
+ DataSet<Edge<Long, Double>> edges = getEdgeDataSet(env);
+
+ Graph<Long, Double, Double> graph = Graph.fromDataSet(vertices,
edges, env);
+
+ // Gather the target vertices into a one-element set
+ GatherFunction<Double, Double, HashSet<Double>> gather = new
GreedyGraphColoringGather();
+
+ // Merge the sets between neighbors
+ SumFunction<Double, Double, HashSet<Double>> sum = new
GreedyGraphColoringSum();
+
+ // Find the minimum vertex id in the set which will be
propagated
+ ApplyFunction<Double, Double, HashSet<Double>> apply = new
GreedyGraphColoringApply();
+
+ // Execute the GSA iteration
+ GatherSumApplyIteration<Long, Double, Double, HashSet<Double>>
iteration =
+ graph.createGatherSumApplyIteration(gather,
sum, apply, maxIterations);
+ Graph<Long, Double, Double> result =
graph.runGatherSumApplyIteration(iteration);
+
+ // Extract the vertices as the result
+ DataSet<Vertex<Long, Double>> greedyGraphColoring =
result.getVertices();
+
+ // emit result
+ if (fileOutput) {
+ greedyGraphColoring.writeAsCsv(outputPath, "\n", " ");
+ } else {
+ greedyGraphColoring.print();
+ }
+
+ env.execute("GSA Greedy Graph Coloring");
+ }
+
+ //
--------------------------------------------------------------------------------------------
+ // Greedy Graph Coloring UDFs
+ //
--------------------------------------------------------------------------------------------
+
+ private static final class GreedyGraphColoringGather
+ extends GatherFunction<Double, Double, HashSet<Double>>
{
+ @Override
+ public HashSet<Double> gather(Triplet<Double, Double> triplet) {
+
+ HashSet<Double> result = new HashSet<Double>();
+ result.add(triplet.getSrcVertexValue());
+
+ return result;
+ }
+ };
+
+ private static final class GreedyGraphColoringSum
+ extends SumFunction<Double, Double, HashSet<Double>> {
+ @Override
+ public HashSet<Double> sum(HashSet<Double> newValue,
HashSet<Double> currentValue) {
+
+ HashSet<Double> result = new HashSet<Double>();
+ result.addAll(newValue);
+ result.addAll(currentValue);
+
+ return result;
+ }
+ };
+
+ private static final class GreedyGraphColoringApply
+ extends ApplyFunction<Double, Double, HashSet<Double>> {
+ @Override
+ public void apply(HashSet<Double> set, Double src) {
+ double minValue = src;
+ for (Double d : set) {
+ if (d < minValue) {
+ minValue = d;
+ }
+ }
+
+ // This is the condition that enables the termination
of the iteration
+ if (minValue < src) {
+ setResult(minValue);
+ }
+ }
+ };
+
+ //
--------------------------------------------------------------------------------------------
+ // Util methods
+ //
--------------------------------------------------------------------------------------------
+
+ private static boolean fileOutput = false;
+ private static String vertexInputPath = null;
+ private static String edgeInputPath = null;
+ private static String outputPath = null;
+
+ private static int maxIterations = 16;
+
+ private static boolean parseParameters(String[] args) {
+
+ if(args.length > 0) {
+ // parse input arguments
+ fileOutput = true;
+
+ if(args.length != 4) {
+ System.err.println("Usage:
GSAGreedyGraphColoringExample <vertex path> <edge path> " +
+ "<result path> <max
iterations>");
+ return false;
+ }
+
+ vertexInputPath = args[0];
+ edgeInputPath = args[1];
+ outputPath = args[2];
+ maxIterations = Integer.parseInt(args[3]);
+ } else {
+ System.out.println("Executing GSA Greedy Graph Coloring
example with built-in default data.");
+ System.out.println(" Provide parameters to read input
data from files.");
+ System.out.println(" See the documentation for the
correct format of input files.");
+ System.out.println(" Usage:
GSAGreedyGraphColoringExample <vertex path> <edge path> "
+ + "<result path> <max iterations>");
+ }
+ return true;
+ }
+
+ private static DataSet<Vertex<Long, Double>>
getVertexDataSet(ExecutionEnvironment env) {
+ if(fileOutput) {
+ return env
+ .readCsvFile(vertexInputPath)
+ .fieldDelimiter(" ")
+ .lineDelimiter("\n")
+ .types(Long.class, Double.class)
+ .map(new MapFunction<Tuple2<Long,
Double>, Vertex<Long, Double>>() {
+ @Override
+ public Vertex<Long, Double>
map(Tuple2<Long, Double> value) throws Exception {
+ return new Vertex<Long,
Double>(value.f0, value.f1);
+ }
+ });
+ } else {
+ return ExampleUtils.getLongDoubleVertexData(env);
--- End diff --
This is just a cosmetic bug, but I think it could be useful to mention
it...
Could you, instead of ExampleUtils, take the data from a separate class?
For SSSP for example, you have SingleSourceShortestPathsData in example/utils.
This would be more legible(i.e. it would look nicer than getLongLongVertexData
:) ).
Also @vasia , I see nobody else is using that method in ExampleUtils so
maybe after this we can get rid of it :D
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