spark取一串字的topN

Java：

package cn.spark.sparktest;

import org.apache.spark.SparkConf;
import org.apache.spark.SparkContext;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.api.java.function.PairFunction;
import scala.Tuple2;

import java.util.List;

public class top3 {
    public static void main(String[] args){
        SparkConf conf = new SparkConf().setMaster("local").setAppName("top3");
        JavaSparkContext sc = new JavaSparkContext(conf);

        JavaRDD<String> lines = sc.textFile("C://Users//Desktop//top.txt");
//對讀取的的RDD進行map操作
        JavaPairRDD<Integer,String> pairs = lines.mapToPair(new PairFunction<String, Integer, String>() {
            @Override
            public Tuple2<Integer, String> call(String s) throws Exception {
                return new Tuple2<Integer, String>(Integer.valueOf(s),s);
            }
        });

        JavaPairRDD<Integer,String> sortPair = pairs.sortByKey(false);
//只取出數組中的第一列元素
        JavaRDD<Integer> result = sortPair.map(new Function<Tuple2<Integer, String>, Integer>() {
            @Override
            public Integer call(Tuple2<Integer, String> i) throws Exception {
                return i._1;
            }
        });

        List<Integer> sortList = result.take(3);

        for (Integer n : sortList){
            System.out.println(n);
        }

        sc.close();
    }
}

測試：

Scala

package cn.spark.study.core

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

object top3 {
  def main(args: Array[String]): Unit = {


    val conf = new SparkConf()
      .setMaster("local")
      .setAppName("top3")
    val sc = new SparkContext(conf)

    val lines = sc.textFile("C://Users//Desktop//top.txt")

    val sort = lines.map(sort => (sort.toInt, sort))
    val result = sort.sortByKey(false)
    val mid = result.map(x => (x._1))
    val top = mid.take(3)

    for (num <- top) {
      println(num)
    }
  }
}

測試：