直接上代码：
package horizon.graphx.util
import java.security.InvalidParameterException
import horizon.graphx.util.CollectionUtil.CollectionHelper
import org.apache.spark.graphx._
import org.apache.spark.rdd.RDD
import org.apache.spark.storage.StorageLevel
import scala.collection.mutable.ArrayBuffer
import scala.reflect.ClassTag
/**
* Created by yepei.ye on 2017/1/19.
* Description:用于在图中为指定的节点计算这些节点的N度关系节点，输出这些节点与源节点的路径长度和节点id
*/
object GraphNdegUtil {
val maxNDegVerticesCount = 10000
val maxDegree = 1000
/**
* 计算节点的N度关系
*
* @param edges
* @param choosedVertex
* @param degree
* @tparam ED
* @return
*/
def aggNdegreedVertices[ED: ClassTag](edges: RDD[(VertexId, VertexId)], choosedVertex: RDD[VertexId], degree: Int): VertexRDD[Map[Int, Set[VertexId]]] = {
val simpleGraph = Graph.fromEdgeTuples(edges, 0, Option(PartitionStrategy.EdgePartition2D), StorageLevel.MEMORY_AND_DISK_SER, StorageLevel.MEMORY_AND_DISK_SER)
aggNdegreedVertices(simpleGraph, choosedVertex, degree)
}
def aggNdegreedVerticesWithAttr[VD: ClassTag, ED: ClassTag](graph: Graph[VD, ED], choosedVertex: RDD[VertexId], degree: Int, sendFilter: (VD, VD) => Boolean = (_: VD, _: VD) => true): VertexRDD[Map[Int, Set[VD]]] = {
val ndegs: VertexRDD[Map[Int, Set[VertexId]]] = aggNdegreedVertices(graph, choosedVertex, degree, sendFilter)
val flated: RDD[Ver[VD]] = ndegs.flatMap(e => e._2.flatMap(t => t._2.map(s => Ver(e._1, s, t._1, null.asInstanceOf[VD])))).persist(StorageLevel.MEMORY_AND_DISK_SER)
val matched: RDD[Ver[VD]] = flated.map(e => (e.id, e)).join(graph.vertices).map(e => e._2._1.copy(attr = e._2._2)).persist(StorageLevel.MEMORY_AND_DISK_SER)
flated.unpersist(blocking = false)
ndegs.unpersist(blocking = false)
val grouped: RDD[(VertexId, Map[Int, Set[VD]])] = matched.map(e => (e.source, ArrayBuffer(e))).reduceByKey(_ ++= _).map(e => (e._1, e._2.map(t => (t.degree, Set(t.attr))).reduceByKey(_ ++ _).toMap))
matched.unpersist(blocking = false)
VertexRDD(grouped)
}
def aggNdegreedVertices[VD: ClassTag, ED: ClassTag](graph: Graph[VD, ED],
choosedVertex: RDD[VertexId],
degree: Int,
sendFilter: (VD, VD) => Boolean = (_: VD, _: VD) => true
): VertexRDD[Map[Int, Set[VertexId]]] = {
if (degree < 1) {
throw new InvalidParameterException("度参数错误:" + degree)
}
val initVertex = choosedVertex.map(e => (e, true)).persist(StorageLevel.MEMORY_AND_DISK_SER)
var g: Graph[DegVertex[VD], Int] = graph.outerJoinVertices(graph.degrees)((_, old, deg) => (deg.getOrElse(0), old))
.subgraph(vpred = (_, a) => a._1 <= maxDegree)
//去掉大节点
.outerJoinVertices(initVertex)((id, old, hasReceivedMsg) => {
DegVertex(old._2, hasReceivedMsg.getOrElse(false), ArrayBuffer((id, 0))) //初始化要发消息的节点
}).mapEdges(_ => 0).cache() //简化边属性
choosedVertex.unpersist(blocking = false)
var i = 0
var prevG: Graph[DegVertex[VD], Int] = null
var newVertexRdd: VertexRDD[ArrayBuffer[(VertexId, Int)]] = null
while (i < degree + 1) {
prevG = g
//发第i+1轮消息
newVertexRdd = prevG.aggregateMessages[ArrayBuffer[(VertexId, Int)]](sendMsg(_, sendFilter), (a, b) => reduceVertexIds(a ++ b)).persist(StorageLevel.MEMORY_AND_DISK_SER)
g = g.outerJoinVertices(newVertexRdd)((vid, old, msg) => if (msg.isDefined) updateVertexByMsg(vid, old, msg.get) else old.copy(init = false)).cache()
prevG.unpersistVertices(blocking = false)
prevG.edges.unpersist(blocking = false)
newVertexRdd.unpersist(blocking = false)
i += 1
}
newVertexRdd.unpersist(blocking = false)
val maped = g.vertices.join(initVertex).mapValues(e => sortResult(e._1)).persist(StorageLevel.MEMORY_AND_DISK_SER)
initVertex.unpersist()
g.unpersist(blocking = false)
VertexRDD(maped)
}
private case class Ver[VD: ClassTag](source: VertexId, id: VertexId, degree: Int, attr: VD = null.asInstanceOf[VD])
private def updateVertexByMsg[VD: ClassTag](vertexId: VertexId, oldAttr: DegVertex[VD], msg: ArrayBuffer[(VertexId, Int)]): DegVertex[VD] = {
val addOne = msg.map(e => (e._1, e._2 + 1))
val newMsg = reduceVertexIds(oldAttr.degVertices ++ addOne)
oldAttr.copy(init = msg.nonEmpty, degVertices = newMsg)
}
private def sortResult[VD: ClassTag](degs: DegVertex[VD]): Map[Int, Set[VertexId]] = degs.degVertices.map(e => (e._2, Set(e._1))).reduceByKey(_ ++ _).toMap
case class DegVertex[VD: ClassTag](var attr: VD, init: Boolean = false, degVertices: ArrayBuffer[(VertexId, Int)])
case class VertexDegInfo[VD: ClassTag](var attr: VD, init: Boolean = false, degVertices: ArrayBuffer[(VertexId, Int)])
private def sendMsg[VD: ClassTag](e: EdgeContext[DegVertex[VD], Int, ArrayBuffer[(VertexId, Int)]], sendFilter: (VD, VD) => Boolean): Unit = {
try {
val src = e.srcAttr
val dst = e.dstAttr
//只有dst是ready状态才接收消息
if (src.degVertices.size < maxNDegVerticesCount && (src.init || dst.init) && dst.degVertices.size < maxNDegVerticesCount && !isAttrSame(src, dst)) {
if (sendFilter(src.attr, dst.attr)) {
e.sendToDst(reduceVertexIds(src.degVertices))
}
if (sendFilter(dst.attr, dst.attr)) {
e.sendToSrc(reduceVertexIds(dst.degVertices))
}
}
} catch {
case ex: Exception =>
println(s"==========error found: exception:${ex.getMessage}," +
s"edgeTriplet:(srcId:${e.srcId},srcAttr:(${e.srcAttr.attr},${e.srcAttr.init},${e.srcAttr.degVertices.size}))," +
s"dstId:${e.dstId},dstAttr:(${e.dstAttr.attr},${e.dstAttr.init},${e.dstAttr.degVertices.size}),attr:${e.attr}")
ex.printStackTrace()
throw ex
}
}
private def reduceVertexIds(ids: ArrayBuffer[(VertexId, Int)]): ArrayBuffer[(VertexId, Int)] = ArrayBuffer() ++= ids.reduceByKey(Math.min)
private def isAttrSame[VD: ClassTag](a: DegVertex[VD], b: DegVertex[VD]): Boolean = a.init == b.init && allKeysAreSame(a.degVertices, b.degVertices)
private def allKeysAreSame(a: ArrayBuffer[(VertexId, Int)], b: ArrayBuffer[(VertexId, Int)]): Boolean = {
val aKeys = a.map(e => e._1).toSet
val bKeys = b.map(e => e._1).toSet
if (aKeys.size != bKeys.size || aKeys.isEmpty) return false
aKeys.diff(bKeys).isEmpty && bKeys.diff(aKeys).isEmpty
}
}
其中sortResult方法里对Traversable[(K,V)]类型的集合使用了reduceByKey方法，这个方法是自行封装的，使用时需要导入，代码如下：
/**
* Created by yepei.ye on 2016/12/21.
* Description:
*/
object CollectionUtil {
/**
* 对具有Traversable[(K, V)]类型的集合添加reduceByKey相关方法
*
* @param collection
* @param kt
* @param vt
* @tparam K
* @tparam V
*/
implicit class CollectionHelper[K, V](collection: Traversable[(K, V)])(implicit kt: ClassTag[K], vt: ClassTag[V]) {
def reduceByKey(f: (V, V) => V): Traversable[(K, V)] = collection.groupBy(_._1).map { case (_: K, values: Traversable[(K, V)]) => values.reduce((a, b) => (a._1, f(a._2, b._2))) }
/**
* reduceByKey的同时，返回被reduce掉的元素的集合
*
* @param f
* @return
*/
def reduceByKeyWithReduced(f: (V, V) => V)(implicit kt: ClassTag[K], vt: ClassTag[V]): (Traversable[(K, V)], Traversable[(K, V)]) = {
val reduced: ArrayBuffer[(K, V)] = ArrayBuffer()
val newSeq = collection.groupBy(_._1).map {
case (_: K, values: Traversable[(K, V)]) => values.reduce((a, b) => {
val newValue: V = f(a._2, b._2)
val reducedValue: V = if (newValue == a._2) b._2 else a._2
val reducedPair: (K, V) = (a._1, reducedValue)
reduced += reducedPair
(a._1, newValue)
})
}
(newSeq, reduced.toTraversable)
}
}
}
总结
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