如何使用scala在矢量中找到字數？

Question

我想在矢量字計數，例如，

我的載體是：

Vector(pen, pencil, pen pencil) 
Vector(pencil, book, eraser, pencil book, pencil eraser, book eraser, pencil book eraser) 
Vector(pen, pencil, book, pen pencil, pen book, pencil book, pen pencil book) 

我想計數爲，

(pen,2) 
(pencil,3) 
(pen pencil,2) 
(book,2) 
(eraser,1) 
(pencil book,2) 
(pencil eraser,1) 
(book eraser,1) 
(pencil book eraser,1) 
(pen book,1) 
(pen pencil book,1) 

Answer 1

這裏有一個快速的解決方案（可能不最高效的，如果這是一個問題）：

val v1 = Vector("pen", "pencil", "pen pencil") 
val v2 = Vector("pencil", "book", "eraser", "pencil book", "pencil eraser", "book eraser", "pencil book eraser") 
val v3 = Vector("pen", "pencil", "book", "pen pencil", "pen book", "pencil book", "pen pencil book") 

(v1 ++ v2 ++ v3).groupBy(v => v).mapValues(_.size) 

res1: scala.collection.immutable.Map[String,Int] = Map(pencil book eraser -> 1, pencil eraser -> 1, eraser -> 1, book eraser -> 1, pen pencil -> 2, book -> 2, pen pencil book -> 1, pencil -> 3, pen -> 2, pen book -> 1, pencil book -> 2)