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Spark Transformation —— intersection

2016-07-22 19:52 162 查看
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.collect
res42: 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.collect
res43: Array[Int] = Array(2, 3)

scala> rdd1.intersection(rdd2).collect
res45: 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.size
res46: 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.size
res47: Int = 2
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标签:  spark 合并集合 去重