Scala深入浅出实战经典：6,Map、Tuple、Zip实战解析

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Map操作，
//> 标记是因为在scala worksheet上即时显示执行结果的标识符，类似shell命令行

//定义一个可变的map
val map = scala.collection.mutable.Map("book"->10,"Run"->12,"IPad"->111)
//循环map，把其值赋给k,v ，然后再把v*0.9
for((k,v)<-map) yield (k,v * 0.9)
//结果
res24: scala.collection.mutable.Map[String,Double] = Map(book -> 9.0, Run -> 10.8, IPad -> 99.9)

//getOrElse
 val hadoopScore = map.getOrElse("book", "is null")
 //> hadoopScore  : Any = 10
 val hadoopScore = map.getOrElse("books", "is null")
 //> hadoopScore  : Any = is null

 //给map增加一个k，v
 map += ("R"->90) 
 //> res25: com.wy.scala.ScalaInAction.map.type = Map(book -> 10, R -> 90, Run -> 12, IPad -> 111)
 //给map去除一个k，v
  map -= "Run"
  //> res26: com.wy.scala.ScalaInAction.map.type = Map(book -> 10, R -> 90, IPad  -> 111)

//map 排序
val sortedScore = scala.collection.immutable.SortedMap("Spark"->11,"Hadoop"->12,"Scala"->14)
//结果，可以看到他们是按map的key的字典排序的
//> sortedScore  : scala.collection.immutable.SortedMap[String,Int] = Map(Hadoop -> 12, Scala -> 14, Spark -> 11)

Tuple,

//定义一个tuple
val tuple =(1,2,3.14,"Rocky","Spark")      
//> tuple  : (Int, Int, Double, String, String) = (1,2,3.14,Rocky,Spark)
//取出tuple的第三个数据
val tv = tuple._3                          
//> tv  : Double = 3.14
//把tuple赋值给--，他们会自动对应，并类型推导
val (first,second,third,four,five) = tuple 
//> first  : Int = 1
    second  : Int = 2
    third  : Double = 3.14
    four  : String = Rocky
    five  : String = Spark
//占位符，但是只取了前俩个
val (f,ss,_,_,_) = tuple                   
//> f  : Int = 1
    ss  : Int = 2
//错误
val (ff,sss) = tuple

//partition分组,大写的归为一组
"Rock Spark".partition(_.isUpper)          
//> res27: (String, String) = (RS,ock park)

Zip，

//zip操作
val zip1 = Array("[","-","]")              
//> zip1  : Array[String] = Array([, -, ])
val zip2 = Array(2,5,2)                    
//> zip2  : Array[Int] = Array(2, 5, 2)
val zip3 = zip1.zip(zip2)                  
//> zip3  : Array[(String, Int)] = Array(([,2), (-,5), (],2))

//打印2次【,打印5次-,打印2次】
       for ((x,y) <- zip3) Console.print(x*y)
//？在worksheet里，这里并没有打印出结果[[-----]]，重新在一个Object里写了下代码，run了一下，控制台就能打印“[[-----]]”，郁闷...  难道在worksheet里的打印到控制台操作不能响应？

so easy …