apache-spark - Apache Spark GraphX 连接组件

Question

如何使用子图函数获取仅包含来自特定连接组件的顶点和边的图？假设我知道连接组件 id，最终目标是基于连接组件创建一个新图。我想保留原始图中的顶点属性。

Answer 1

您必须将带有组件 ID 的图连接到原始图，按组件 ID 过滤(取子图)，然后丢弃组件 ID。

import scala.reflect._
import org.apache.spark.graphx._
import org.apache.spark.graphx.lib.ConnectedComponents

def getComponent[VD: ClassTag, ED: ClassTag](
    g: Graph[VD, ED], component: VertexId): Graph[VD, ED] = {
  val cc: Graph[VertexId, ED] = ConnectedComponents.run(g)
  // Join component ID to the original graph.
  val joined = g.outerJoinVertices(cc.vertices) {
    (vid, vd, cc) => (vd, cc)
  }
  // Filter by component ID.
  val filtered = joined.subgraph(vpred = {
    (vid, vdcc) => vdcc._2 == Some(component)
  })
  // Discard component IDs.
  filtered.mapVertices {
    (vid, vdcc) => vdcc._1
  }
}