Spark 学习笔记之 union/intersection/subtract

union/intersection/subtract：

import org.apache.spark.SparkContext
import org.apache.spark.rdd.RDD
import org.apache.spark.sql.SparkSession

object TransformationsDemo {
  def main(args: Array[String]): Unit = {
    val sparkSession = SparkSession.builder().appName("TransformationsDemo").master("local[1]").getOrCreate()
    val sc = sparkSession.sparkContext
    testUnion(sc)
    testIntersection(sc)
    testSubtract(sc)

  }

  private def testSubtract(sc: SparkContext) = {
    val rdd1 = sc.parallelize(1 to 3, 1)
    val rdd2 = sc.parallelize(3 to 5, 1)
    //返回在当前RDD中出现，并且不在另一个RDD中出现的元素，不去重。
    rdd1.subtract(rdd2).collect().foreach(println)
    println(s"partitions: ${rdd1.subtract(rdd2, 1).partitions.size}")
    println(s"partitions: ${rdd1.subtract(rdd2, 2).partitions.size}")

    val rdd3 = sc.parallelize(List(List(1, 2, 3), List(4, 5, 6)), 1)
    val rdd4 = sc.parallelize(List(List(4, 5, 6), List(7, 8, 9)), 1)
    rdd3.subtract(rdd4).collect().foreach(println)
  }

  private def testIntersection(sc: SparkContext) = {
    val rdd1 = sc.parallelize(1 to 2, 1)
    val rdd2 = sc.parallelize(3 to 5, 1)
    //返回两个RDD的交集，并且去重。
    rdd1.intersection(rdd2).collect().foreach(println)
    println(s"partitions: ${rdd1.intersection(rdd2, 1).partitions.size}")
    println(s"partitions: ${rdd1.intersection(rdd2, 2).partitions.size}")

    val rdd3 = sc.parallelize(List(List(1, 2, 3), List(4, 5, 6)), 1)
    val rdd4 = sc.parallelize(List(List(4, 5, 6), List(7, 8, 9)), 1)
    rdd3.intersection(rdd4).collect().foreach(println)
  }

  private def testUnion(sc: SparkContext) = {
    val rdd1 = sc.parallelize(1 to 3, 1)
    val rdd2 = sc.parallelize(3 to 5, 1)
    //将两个RDD进行合并，不去重。
    rdd1.union(rdd2).collect().foreach(println)

    val rdd3 = sc.parallelize(List(List(1, 2, 3), List(4, 5, 6)), 1)
    val rdd4 = sc.parallelize(List(List(4, 5, 6), List(7, 8, 9)), 1)
    rdd3.union(rdd4).collect().foreach(println)
  }

}

运行结果：