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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-2561) Sync Gelly Java and Scala APIs
Date Wed, 07 Oct 2015 16:18:26 GMT

    [ https://issues.apache.org/jira/browse/FLINK-2561?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14947128#comment-14947128
] 

ASF GitHub Bot commented on FLINK-2561:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1211#discussion_r41411193
  
    --- Diff: flink-staging/flink-gelly-scala/src/main/scala/org/apache/flink/graph/scala/example/SingleSourceShortestPaths.scala
---
    @@ -0,0 +1,170 @@
    +/*
    + * 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.scala.example;
    +
    +import org.apache.flink.api.scala._
    +import org.apache.flink.graph.scala._
    +import org.apache.flink.types.NullValue
    +import org.apache.flink.graph.Edge
    +import org.apache.flink.api.common.functions.MapFunction
    +import org.apache.flink.graph.spargel.VertexUpdateFunction
    +import org.apache.flink.graph.spargel.MessageIterator
    +import org.apache.flink.graph.Vertex
    +import org.apache.flink.graph.spargel.MessagingFunction
    +import scala.collection.JavaConversions._
    +import org.apache.flink.graph.scala.utils.Tuple3ToEdgeMap
    +import org.apache.flink.graph.example.utils.SingleSourceShortestPathsData
    +
    +/**
    + * This example shows how to use Gelly's vertex-centric iterations.
    + * 
    + * It is an implementation of the Single-Source-Shortest-Paths algorithm. 
    + *
    + * The input file is a plain text file and must be formatted as follows:
    + * Edges are represented by tuples of srcVertexId, trgVertexId, distance which are
    + * separated by tabs. Edges themselves are separated by newlines.
    + * For example: <code>1\t2\t0.1\n1\t3\t1.4\n</code> defines two edges,
    + * edge 1-2 with distance 0.1, and edge 1-3 with distance 1.4.
    + *
    + * If no parameters are provided, the program is run with default data from
    + * [[org.apache.flink.graph.example.utils.SingleSourceShortestPathsData]]
    + */
    +object SingleSourceShortestPaths {
    +  def main(args: Array[String]) {
    +    if (!parseParameters(args)) {
    +      return
    +    }
    +
    +    val env = ExecutionEnvironment.getExecutionEnvironment
    +    val edges: DataSet[Edge[Long, Double]] = getEdgesDataSet(env)
    +    val graph = Graph.fromDataSet[Long, Double, Double](edges, new InitVertices(srcVertexId),
env)
    +
    +    // Execute the vertex-centric iteration
    +    val result = graph.runVertexCentricIteration(new VertexDistanceUpdater,
    +      new MinDistanceMessenger, maxIterations)
    +
    +    // Extract the vertices as the result
    +    val singleSourceShortestPaths = result.getVertices
    +
    +    // emit result
    +    if (fileOutput) {
    +      singleSourceShortestPaths.writeAsCsv(outputPath, "\n", ",")
    +      env.execute("Single Source Shortest Paths Example")
    +     } else {
    +        singleSourceShortestPaths.print()
    +     }
    +  }
    +
    +  // --------------------------------------------------------------------------------------------
    +  //  Single Source Shortest Path UDFs
    +  // --------------------------------------------------------------------------------------------
    +
    +  private final class InitVertices(srcId: Long) extends MapFunction[Long, Double] {
    +
    +    override def map(id: Long) = {
    +      if (id.equals(srcId)) {
    +        0.0
    +      } else {
    +        Double.PositiveInfinity
    +      }
    +    }
    +  }
    +
    +  /**
    +   * Function that updates the value of a vertex by picking the minimum
    +   * distance from all incoming messages.
    +   */
    +  private final class VertexDistanceUpdater extends VertexUpdateFunction[Long, Double,
Double] {
    +
    +    override def updateVertex(vertex: Vertex[Long, Double], inMessages: MessageIterator[Double])
{
    +      var minDistance = Double.MaxValue
    +      while (inMessages.hasNext) {
    +        var msg = inMessages.next
    +        if (msg < minDistance) {
    +          minDistance = msg
    +        }
    +      }
    +      if (vertex.getValue > minDistance) {
    +        setNewVertexValue(minDistance)
    +      }
    +    }
    +  }
    +
    +  /**
    +   * Distributes the minimum distance associated with a given vertex among all
    +   * the target vertices summed up with the edge's value.
    +   */
    +  private final class MinDistanceMessenger extends
    +    MessagingFunction[Long, Double, Double, Double] {
    +
    +    override def sendMessages(vertex: Vertex[Long, Double]) {
    +      for (edge: Edge[Long, Double] <- getEdges) {
    +        sendMessageTo(edge.getTarget(), vertex.getValue + edge.getValue)
    +      }
    +    }
    +  }
    +
    +  // ****************************************************************************
    +  // UTIL METHODS
    +  // ****************************************************************************
    +
    +  private var fileOutput = false
    +  private var srcVertexId = 1L
    +  private var edgesInputPath: String = null
    +  private var outputPath: String = null
    +  private var maxIterations = 5
    +
    +  private def parseParameters(args: Array[String]): Boolean = {
    +    if(args.length > 0) {
    +      if(args.length != 4) {
    +        System.err.println("Usage: SingleSourceShortestPaths <source vertex id>"
+
    +          " <input edges path> <output path> <num iterations>")
    +        false
    +      }
    +    fileOutput = true
    --- End diff --
    
    indention +2 spaces?


> Sync Gelly Java and Scala APIs
> ------------------------------
>
>                 Key: FLINK-2561
>                 URL: https://issues.apache.org/jira/browse/FLINK-2561
>             Project: Flink
>          Issue Type: Task
>          Components: Gelly
>            Reporter: Vasia Kalavri
>            Assignee: Vasia Kalavri
>             Fix For: 0.10
>
>
> There is some functionality and tests missing from the Gelly Scala API. This should be
added, together with documentation, a completeness test and some usage examples.



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