Github user vasia commented on a diff in the pull request:
https://github.com/apache/flink/pull/452#discussion_r26487919
--- Diff:
flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/example/EuclideanGraphExample.java
---
@@ -0,0 +1,231 @@
+/*
+ * 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.Tuple3;
+import org.apache.flink.graph.Edge;
+import org.apache.flink.graph.Graph;
+import org.apache.flink.graph.Triplet;
+import org.apache.flink.graph.Vertex;
+import org.apache.flink.graph.example.utils.EuclideanGraphData;
+
+import java.io.Serializable;
+
+/**
+ * Given a directed, unweighted graph, with vertex values representing
points in a plan,
+ * return a weighted graph where the edge weights are equal to the
Euclidean distance between the
+ * src and the trg vertex values.
+ *
+ * <p>
+ * Input files are plain text files and must be formatted as follows:
+ * <ul>
+ * <li> Vertices are represented by their vertexIds and vertex
values and are separated by newlines,
+ * the value being formed of two doubles separated by a comma.
+ * For example: <code>1,1.0,1.0\n2,2.0,2.0\n3,3.0,3.0\n</code>
defines a data set of three vertices
+ * <li> Edges are represented by triples of srcVertexId,
srcEdgeId, weight which are
+ * separated by commas. Edges themselves are separated by
newlines. The initial edge value will be overwritten.
+ * For example: <code>1,2,13.0\n1,3,6.0\n</code> defines two edges
1-2 and 1-3 having
+ * weights 13 and 6 respectively.
+ * </ul>
+ * </p>
+ *
+ * Usage <code>EuclideanDistanceExample <vertex path> <edge
path> <result path></code><br>
+ * If no parameters are provided, the program is ran with default data from
+ * {@link org.apache.flink.graph.example.utils.EuclideanGraphData}
+ */
+@SuppressWarnings("serial")
+public class EuclideanGraphExample implements ProgramDescription {
+
+ public static void main(String[] args) throws Exception {
+
+ if (!parseParameters(args)) {
+ return;
+ }
+
+ ExecutionEnvironment env =
ExecutionEnvironment.getExecutionEnvironment();
+
+ DataSet<Vertex<Long, Point>> vertices = getVerticesDataSet(env);
+
+ DataSet<Edge<Long, Double>> edges = getEdgesDataSet(env);
+
+ Graph<Long, Point, Double> graph = Graph.fromDataSet(vertices,
edges, env);
+
+ DataSet<Triplet<Long, Point, Double>> triplets =
graph.getTriplets();
+
+ // the edge value will be the Euclidean distance between its
src and trg vertex
+ DataSet<Triplet<Long, Point, Double>> resultedTriplets =
triplets
+ .map(new MapFunction<Triplet<Long, Point,
Double>, Triplet<Long, Point, Double>>() {
+
+ @Override
+ public Triplet<Long, Point, Double>
map(Triplet<Long, Point, Double> triplet) throws Exception {
+
+ Vertex<Long, Point> srcVertex =
triplet.getSrcVertex();
+ Vertex<Long, Point> trgVertex =
triplet.getTrgVertex();
+ Edge<Long, Double> edge =
triplet.getEdge();
+
+
edge.setValue(srcVertex.getValue().euclideanDistance(trgVertex.getValue()));
+
+ return new Triplet<Long, Point,
Double>(srcVertex, trgVertex, edge);
+ }
+ });
+
+ // retrieve the edges from the final result
+ DataSet<Edge<Long, Double>> result = resultedTriplets
+ .map(new MapFunction<Triplet<Long, Point,
Double>, Edge<Long, Double>>() {
+
+ @Override
+ public Edge<Long, Double>
map(Triplet<Long, Point, Double> triplet) throws Exception {
+ return triplet.getEdge();
+ }
+ });
+
+ // emit result
+ if (fileOutput) {
+ result.writeAsCsv(outputPath, "\n", ",");
+ } else {
+ result.print();
+ }
+
+ env.execute("Euclidean Graph Example");
+ }
+
+ @Override
+ public String getDescription() {
+ return "Weighing a graph by computing the Euclidean distance " +
+ "between its vertices";
+ }
+
+ //
*************************************************************************
+ // DATA TYPES
+ //
*************************************************************************
+
+ /**
+ * A simple two-dimensional point.
+ */
+ public static class Point implements Serializable {
+
+ public double x, y;
+
+ public Point() {}
+
+ public Point(double x, double y) {
+ this.x = x;
+ this.y = y;
+ }
+
+ public Point add(Point other) {
+ x += other.x;
+ y += other.y;
+ return this;
+ }
+
+ public Point div(long val) {
+ x /= val;
+ y /= val;
+ return this;
+ }
+
+ public double euclideanDistance(Point other) {
+ return Math.sqrt((x-other.x)*(x-other.x) +
(y-other.y)*(y-other.y));
+ }
+
+ public void clear() {
+ x = y = 0.0;
+ }
+
+ @Override
+ public String toString() {
+ return x + " " + y;
+ }
+ }
+
+ //
******************************************************************************************************************
+ // UTIL METHODS
+ //
******************************************************************************************************************
+
+ private static boolean fileOutput = false;
+
+ private static String verticesInputPath = null;
+
+ private static String edgesInputPath = null;
+
+ private static String outputPath = null;
+
+ private static boolean parseParameters(String[] args) {
+
+ if (args.length > 0) {
+ if (args.length == 3) {
+ fileOutput = true;
+ verticesInputPath = args[0];
+ edgesInputPath = args[1];
+ outputPath = args[2];
+ } else {
+ System.out.println("Executing Euclidean Graph
example with default parameters and 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.err.println("Usage:
EuclideanGraphExample <input vertices path> <input edges path>" +
+ " <output path>");
+ return false;
+ }
+ }
+ return true;
+ }
+
+ private static DataSet<Vertex<Long, Point>>
getVerticesDataSet(ExecutionEnvironment env) {
+ if (fileOutput) {
+ return env.readCsvFile(verticesInputPath)
+ .lineDelimiter("\n")
+ .types(Long.class, Double.class,
Double.class)
+ .map(new MapFunction<Tuple3<Long,
Double, Double>, Vertex<Long, Point>>() {
+
+ @Override
+ public Vertex<Long, Point>
map(Tuple3<Long, Double, Double> value) throws Exception {
+ return new Vertex<Long,
Point>(value.f0, new Point(value.f1, value.f2));
+ }
+ });
+ } else {
+ System.err.println("Usage: EuclideanGraphExample <input
vertices path> <input edges path>" +
+ " <output path>");
+ return EuclideanGraphData.getDefaultVertexDataSet(env);
+ }
+ }
+
+ private static DataSet<Edge<Long, Double>>
getEdgesDataSet(ExecutionEnvironment env) {
+ if (fileOutput) {
+ return env.readCsvFile(edgesInputPath)
+ .lineDelimiter("\n")
+ .types(Long.class, Long.class,
Double.class)
+ .map(new MapFunction<Tuple3<Long, Long,
Double>, Edge<Long, Double>>() {
+
+ @Override
+ public Edge<Long, Double>
map(Tuple3<Long, Long, Double> tuple3) throws Exception {
+ return new Edge<Long,
Double>(tuple3.f0, tuple3.f1, tuple3.f2);
+ }
+ });
+ } else {
+ System.err.println("Usage: EuclideanGraphExample <input
vertices path> <input edges path>" +
--- End diff --
same :-)
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