Spark-shell交互式编程
Posted daisy99lijing
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1.该系总共有多少学生
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val par = lines.map(row=>row.split(",")(0)) val distinct_par = par.distinct() //去重操作 distinct_par.count //取得总数
2.该系共开设来多少门课程
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val par = lines.map(row=>row.split(",")(1)) val distinct_par = par.distinct() distinct_par.count
3.Tom 同学的总成绩平均分是多少
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val pare = lines.filter(row=>row.split(",")(0)=="Tom") pare.foreach(println) Tom,DataBase,26 Tom,Algorithm,12 Tom,OperatingSystem,16 Tom,Python,40 Tom,Software,60 pare.map(row=>(row.split(",")(0),row.split(",")(2).toInt)).mapValues(x=>(x,1)).reduceByKey((x,y ) => (x._1+y._1,x._2 + y._2)).mapValues(x => (x._1 / x._2)).collect() //res9: Array[(String, Int)] = Array((Tom,30))
4.求每名同学的选修的课程门数
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val pare = lines.filter(row=>row.split(",")(1)=="DataBase") pare.count res1: Long = 126
5.该系 DataBase 课程共有多少人选修
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val pare = lines.filter(row=>row.split(",")(1)=="DataBase") pare.count res1: Long = 126
6.各门课程的平均分是多少
val lines = sc.textFile("file:///usr/local/spark/sparksqldata/Data01.txt") val pare = lines.map(row=>(row.split(",")(1),row.split(",")(2).toInt)) pare.mapValues(x=>(x,1)).reduceByKey((x,y) => (x._1+y._1,x._2 + y._2)).mapValues(x => (x._1 / x._2)).collect() res0: Array[(String, Int)] = Array((Python,57), (OperatingSystem,54), (CLanguage,50), (Software,50), (Algorithm,48), (DataStructure,47), (DataBase,50), (ComputerNetwork,51))
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