def union(other: RDD[T]): RDD[T]
该函数比较简单，就是将两个RDD进行合并，不去重。
scala> var rdd1 = sc.makeRDD(1 to 2,1)rdd1: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[45] at makeRDD at :21 scala> rdd1.collectres42: Array[Int] = Array(1, 2) scala> var rdd2 = sc.makeRDD(2 to 3,1)rdd2: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[46] at makeRDD at :21 scala> rdd2.collectres43: Array[Int] = Array(2, 3) scala> rdd1.union(rdd2).collectres44: Array[Int] = Array(1, 2, 2, 3)def intersection(other: RDD[T]): RDD[T] def intersection(other: RDD[T], numPartitions: Int): RDD[T] def intersection(other: RDD[T], partitioner: Partitioner)(implicit ord: Ordering[T] = null): RDD[T]
该函数返回两个RDD的交集，并且去重。 参数numPartitions指定返回的RDD的分区数。 参数partitioner用于指定分区函数
scala> var rdd1 = sc.makeRDD(1 to 2,1)rdd1: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[45] at makeRDD at :21 scala> rdd1.collectres42: Array[Int] = Array(1, 2) scala> var rdd2 = sc.makeRDD(2 to 3,1)rdd2: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[46] at makeRDD at :21 scala> rdd2.collectres43: Array[Int] = Array(2, 3) scala> rdd1.intersection(rdd2).collectres45: Array[Int] = Array(2) scala> var rdd3 = rdd1.intersection(rdd2)rdd3: org.apache.spark.rdd.RDD[Int] = MapPartitionsRDD[59] at intersection at :25 scala> rdd3.partitions.sizeres46: Int = 1 scala> var rdd3 = rdd1.intersection(rdd2,2)rdd3: org.apache.spark.rdd.RDD[Int] = MapPartitionsRDD[65] at intersection at :25 scala> rdd3.partitions.sizeres47: Int = 2def subtract(other: RDD[T]): RDD[T] def subtract(other: RDD[T], numPartitions: Int): RDD[T] def subtract(other: RDD[T], partitioner: Partitioner)(implicit ord: Ordering[T] = null): RDD[T]
该函数类似于intersection，但返回在RDD中出现，并且不在otherRDD中出现的元素，不去重。 参数含义同intersection
scala> var rdd1 = sc.makeRDD(Seq(1,2,2,3))rdd1: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[66] at makeRDD at :21 scala> rdd1.collectres48: Array[Int] = Array(1, 2, 2, 3) scala> var rdd2 = sc.makeRDD(3 to 4)rdd2: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[67] at makeRDD at :21 scala> rdd2.collectres49: Array[Int] = Array(3, 4) scala> rdd1.subtract(rdd2).collectres50: Array[Int] = Array(1, 2, 2)