kongkong的专栏

  Scala的变量分为两种：val和var。val跟java的final变量类似，一旦初始化就不能被重新赋值。而var则不同，类似于Java的非final变量，在整个生命周期内var可以被重新赋值。 val msg="Hello"; var msg:String = "hello";                                   ...

  #flatMap val favMovies = sc.parallelize(List("Pulp Fiction","Requiem for a dream","Aclockwork Orange")); favMovies.flatMap(movieTitle=>movieTitle.split(" ")).collect()   #sample val data = s...

spark下载地址：http://spark.apache.org/downloads.html   #解压:    tar -xzvf spark-2.4.0-bin-hadoop2.6.tgz cd  spark-2.4.0-bin-hadoop2.6 #执行命名 进入控制台 ./bin/spark-shell var lines = sc.textFile("README...

val names = List("a", b", "c") names.map(_.toUpperCase) names.foreach(println) names.foreach{ name => println(name) } # res10: List[Int] = List(1, 2, 1, 3, 4, 3, 5) 数据展开 # flatten可以把嵌套的展开 L...