Created
July 22, 2015 22:51
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Connected Component Problem
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package me.invkrh.train | |
import org.apache.spark.{SparkContext, SparkConf} | |
import org.apache.spark.rdd.RDD | |
/** | |
* Created with IntelliJ IDEA. | |
* User: invkrh | |
* Date: 22/07/15 | |
* Time: 23:14 | |
*/ | |
object ConnectedComponent extends App { | |
val conf = new SparkConf() | |
.setAppName(this.getClass.getName) | |
.setMaster("local[*]") | |
val sc = new SparkContext(conf) | |
val arcs = sc.makeRDD(Seq((1, 2), (2, 3), (2, 4), (5, 6))) | |
val input = arcs.flatMap { | |
case pair => Array(pair, pair.swap) | |
}.map { | |
case (left, right) => (Set(left), Set(right)) | |
} | |
val output = connectedComponent(input.persist()).keys.collect foreach println | |
def connectedComponent(dataSet: RDD[(Set[Int], Set[Int])]): RDD[(Set[Int], Set[Int])] = { | |
val keys = dataSet.keys | |
val cnt = keys.count() | |
val distCnt = keys.distinct().count() | |
if (cnt != distCnt) { | |
val next = dataSet.reduceByKey(_ union _) | |
.flatMap { case (cc, neighbours) => | |
if (neighbours.nonEmpty) { | |
neighbours.map(n => (cc + n, neighbours - n)) | |
} else { | |
Array((cc, Set[Int]())) | |
} | |
}.persist() | |
next.count() | |
dataSet.unpersist(false) | |
connectedComponent(next) | |
} else { | |
dataSet | |
} | |
} | |
} |
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