使用scala spark中的第一列连接两个数据集

Question

import org.apache.spark.rdd.RDD
import org.apache.spark.{SparkConf, SparkContext}

import scala.io.Source

object spark {
  def main(args: Array[String]): Unit = {
    val sparkConf = new SparkConf().setAppName("FindFrequentPairs").setMaster("local[2]")
    val sc = new SparkContext(sparkConf)
    val text1: RDD[String] = sc.textFile(args(0))
    val text2: RDD[String] = sc.textFile(args(1))

    val joined = text1.join(text2)

('"Please Like Me" (2013) {Rhubarb and Custard (#1.1)}', '$haniqua')
('"Please Like Me" (2013) {Spanish Eggs (#1.5)}', '$haniqua')
('A Woman of Distinction (1950)  (uncredited)', '& Ashour, Lucienne')
('Around the World (1943)  (uncredited)', '& Ashour, Lucienne')
('Chain Lightning (1950)  (uncredited)', '& Ashour, Lucienne')

Answer 1

您必须首先为数据集创建PairRDD，然后应用联接转换。您的数据集看起来不准确。

请考虑下面的例子。

**Dataset1**

a 1
b 2
c 3

**Dataset2**

a 8
b 4

在Scala中，您的代码应该如下所示

val pairRDD1 = sc.textFile("/path_to_yourfile/first.txt").map(line => (line.split(" ")(0),line.split(" ")(1)))

val pairRDD2 = sc.textFile("/path_to_yourfile/second.txt").map(line => (line.split(" ")(0),line.split(" ")(1)))

val joinRDD = pairRDD1.join(pairRDD2)

joinRDD.collect

下面是scala shell的结果

res10: Array[(String, (String, String))] = Array((a,(1,8)), (b,(2,4)))