Spark组件之GraphX学习11--PageRank例子（PageRankAboutBerkeleyWiki）

更多代码请见：https://github.com/xubo245/SparkLearning

1解释

使用PageRank来对wiki中有关berkeley的链接进行计算，取top（10）

2.代码：

/**
 * @author xubo
 * ref http://spark.apache.org/docs/1.5.2/graphx-programming-guide.html
 * time 20160503
 */

package org.apache.spark.graphx.learning

import org.apache.log4j.{Level, Logger}
import org.apache.spark.{SparkContext, SparkConf}
import org.apache.spark.graphx._
import org.apache.spark.rdd.RDD

object PageRankAboutBerkeleyWiki {
  def main(args: Array[String]) {
    //屏蔽日志
    Logger.getLogger("org.apache.spark").setLevel(Level.WARN)
    Logger.getLogger("org.eclipse.jetty.server").setLevel(Level.OFF)

    //设置运行环境
    val conf = new SparkConf().setAppName("PageRankAboutBerkeleyWiki").setMaster("local")
    val sc = new SparkContext(conf)

    //读入数据文件
    val articles: RDD[String] = sc.textFile("file/data/graphx/input/graphx-wiki-vertices.txt")
    val links: RDD[String] = sc.textFile("file/data/graphx/input/graphx-wiki-edges.txt")

    //装载顶点和边
    val vertices = articles.map { line =>
      val fields = line.split('\t')
      (fields(0).toLong, fields(1))
    }

    val edges = links.map { line =>
      val fields = line.split('\t')
      Edge(fields(0).toLong, fields(1).toLong, 0)
    }

    //cache操作
    //val graph = Graph(vertices, edges, "").persist(StorageLevel.MEMORY_ONLY_SER)
    val graph = Graph(vertices, edges, "").persist()
    //graph.unpersistVertices(false)

    //测试
    println("**********************************************************")
    println("获取5个triplet信息")
    println("**********************************************************")
    graph.triplets.take(5).foreach(println(_))

    //pageRank算法里面的时候使用了cache()，故前面persist的时候只能使用MEMORY_ONLY
    println("**********************************************************")
    println("PageRank计算，获取最有价值的数据")
    println("**********************************************************")
    val prGraph = graph.pageRank(0.001).cache()

    val titleAndPrGraph = graph.outerJoinVertices(prGraph.vertices) {
      (v, title, rank) => (rank.getOrElse(0.0), title)
    }

    titleAndPrGraph.vertices.top(10) {
      Ordering.by((entry: (VertexId, (Double, String))) => entry._2._1)
    }.foreach(t => println(t._2._2 + ": " + t._2._1))

    sc.stop()
  }
}

直接调用

 prGraph = graph.pageRank(0.001).cache()

就行了，0.001为前后两次收敛的误差阈值，小于这个阈值时则结束计算，越小精度越到

3.结果：

**********************************************************
获取5个triplet信息
**********************************************************
((146271392968588,Computer Consoles Inc.),(7097126743572404313,Berkeley Software Distribution),0)
((146271392968588,Computer Consoles Inc.),(8830299306937918434,University of California, Berkeley),0)
((625290464179456,List of Penguin Classics),(1735121673437871410,George Berkeley),0)
((1342848262636510,List of college swimming and diving teams),(8830299306937918434,University of California, Berkeley),0)
((1889887370673623,Anthony Pawson),(8830299306937918434,University of California, Berkeley),0)
**********************************************************
PageRank计算，获取最有价值的数据
**********************************************************
University of California, Berkeley: 1321.111754312097
Berkeley, California: 664.8841977233583
Uc berkeley: 162.50132743397873
Berkeley Software Distribution: 90.4786038848606
Lawrence Berkeley National Laboratory: 81.90404939641944
George Berkeley: 81.85226118457985
Busby Berkeley: 47.871998218019655
Berkeley Hills: 44.76406979519754
Xander Berkeley: 30.324075347288037
Berkeley County, South Carolina: 28.908336483710308

参考

【1】 http://spark.apache.org/docs/1.5.2/graphx-programming-guide.html

【2】https://github.com/xubo245/SparkLearning

【3】 炼数成金视频