scala学习之Map、Tuple、zip

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默认Map是不可变的Map

val map=Map("book"->10,"gun"->18,"ipad"->1000)//map: scala.collection.immutable.Map[String,Int] = Map(book -> 10, gun -> 18, ipad -> 1000)</span>

构造一个可以变的Map[String,Int],其值是可以变化的

val bmap=scala.collection.mutable.Map("book"->10,"gun"->18,"ipad"->1000)

通过已有Map创建Map

val d=for((k,v) <- map) yield (k,v*2)//d: scala.collection.immutable.Map[String,Int] = Map(book -> 20, gun -> 36, ipad-> 2000)</span>

val b=d.getOrElse("book",0)//b: Int =20val bmap=scala.collection.mutable.Map("book"->10,"gun"->18,"ipad"->1000)val mybook=bmap.getOrElse("book",0)//mybook: Int = 10bmap+=("gpl"->66)//res0: bmap.type = Map(book -> 10, gun -> 18, ipad -> 1000, gpl -> 66)bmap-="gpl"//res1: bmap.type = Map(book -> 10, gun -> 18, ipad -> 1000)val sortedMap=scala.collection.immutable.SortedMap("scala"->7,"hadoop"->8,"spark"->9)//sortedMap: scala.collection.immutable.SortedMap[String,Int] = Map(hadoop -> 8, scala -> 7, spark -> 9)//按key排序</span>

Tuple:

元组(tuple) 中可以是不同类型的值

val tuple=(100,"gpl","yl",'a')//print(tuple._1+" "+tuple._2+" "+tuple._3)print(tuple._1)print(tuple._2)print(tuple._3)

val tuple=(1,2,3,14,"scala","spark")val third=tuple._3//third: Int = 3val (first,second,third,fourth,fifth,six)=tupleval (first,second,third,fourth,_,_)=tupleval s="Rocky Spark".partition(_.isUpper)//s: (String, String) = (RS,ocky park)

zip:

//zipval symbols=Array("1","4","2")val counts=Array(2,5,2)val pairs=symbols.zip(counts)pairs: Array[(String, Int)] = Array((1,2), (4,5), (2,2))

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