對於元組的關鍵元素的Scala圖，如何從元組中選擇（項目？）特定項目？

Question

假設我有一個具有多屬性值的地圖，我想選擇一個特定的屬性。

例如，表示具有姓名，性別，年齡，說明的人員的表格的地圖。

在SQL中，我會寫「選擇的人年齡其中名稱=‘任何人’」

我怎麼才能在斯卡拉這種效果？

val people = Map(
"Walter White" -> ("male",52,"bad boy"), 
"Skyler White" -> ("female",42,"morally challenged mom") 
) 

// equivalent of select * from people. This works. 
for ((name,(gender,age,desc)) <- people) println(s"$name is a $age year old $gender and is a $desc") 

// what should be the syntax to get "the age of Walter White is 52"? 
// in SQL, it would be "'The age of Walter White is ' || (select age from people where name='Walter White')" 
// what would it be in Scala? 
println("The age of Walter White is " + people("Walter White")(1)) // not this! 

Answer 1

您可以創建一個Person案例類，並創建Person！而非元組新的地圖。

case class Person(name: String, gender: String, age: Int, description: String) 

val persons = people map { case (name, (gender, age, descr)) => 
    name -> Person(name, gender, age, descr) 
} 

這種方式，你可以寫：

persons("Walter White").age    // Int = 52 
persons.get("Skyler White").map(_.age) // Option[Int] = Some(42) 

你也可以使用原來的代碼訪問的年齡：

people("Walter White")._2    // Int = 52