scala二次排序实现

二次排序就是按照不同字段进行排序

package test1

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


class secondSort(val first:Int,val second:Int) extends Ordered[secondSort] with Serializable {
  override def compare(that: secondSort): Int = {
    if (this.first != that.first){
      this.first - that.first
    }else{
      this.second - that.second
    }

  }
}
object test{
  def main(args: Array[String]): Unit = {
    val conf = new SparkConf().setAppName("second").setMaster("local")
    val sc = new SparkContext(conf)
     val arr = Array((2,1),(2,4),(2,3),(5,2),(5,4),(5,2),(4,3),(4,2),(4,1))
    sc.makeRDD(arr)
      .map(a=>(new secondSort(a._1,a._2),a))
      .sortByKey()
      .foreach(a=>
      println(a._2+"\t"))
      //    sc.textFile("D:\\a\\a.txt")
//      .map(a=>(new secondSort(a.split(",")(0).toInt,a.split(",")(1).toInt),a))
//      .sortByKey()
//      .foreach(a=>
//      println(a._2+"\t")
//      )
  }
}

类似于MapReduce里面的分组+排序的实现