#daimonscala 22 My Work

gistfile1.scala

// -----------------
// #daimonscala 22 ハンズオン

// -----------------
// 1. ListからMapをつくろう

val list = List("Scala", "http://scala-lang.org", "Java", "http://java.net/", "Haskell", "http://haskell.org/")

// Map(Scala -> http://scala-lang.org, Java -> http://java.net/, Haskell -> http://haskell.org/)



// -----------------
// 2. ユニークに絞り込もう

val list = List(1,2,1,3,2,4,4,2,4,3)

// List(1, 2, 3, 4)



// -----------------
// 3. 並び替えて平方にしよう

val list = List(2,3,0,1,5,4)

// List(0, 1, 4, 9, 16, 25)



// -----------------
// 4. for式を使って以下のようなListをつくろう

List(
  (1,1,1), 
  (2,1,2), 
  (2,2,4), 
  (3,1,3), 
  (3,2,6), 
  (3,3,9), 
  (4,1,4), 
  (4,2,8), 
  (4,3,12), 
  (4,4,16), 
  (5,1,5), 
  (5,2,10), 
  (5,3,15), 
  (5,4,20), 
  (5,5,25)
)



// -----------------
// 5. CSVを出力しよう

val h = List("name","lang","country")
val ds = List(("Andy","Scala","Japan"),("Brian","Python","America"),("Samir","Java","India"))

// name,lang,country
// Andy,Scala,Japan
// Brian,Python,America
// Samir,Java,India



// -----------------
// 6. 未成年と成人に分類しよう

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

val people = List(
  Person("Andy",34), 
  Person("Bob",18), 
  Person("Charles",45), 
  Person("Eric",13)
)

// adults: List[Person] = List(Person(Andy,34), Person(Charles,45))
// minors: List[Person] = List(Person(Bob,18), Person(Eric,13))



// -----------------
// 7. 並列コレクションを使ってみよう（Scala 2.9.0以降）

Range(1,100).par foreach { e => print(e +",") }



// -----------------
// 8. flatMapを使ってみよう1

val input = List(1,2,3,"a","3",4)

val square = (a: Any) => a match {
  case i: Int => Some(i*i)
  case _ => None
}

// List(1, 4, 9, 16)



// -----------------
// 9. flatMapを使ってみよう2

case class Device(name: String)
case class User(name: String, devices: List[Device])

val users = List(
  User("Andy",    List(Device("iPhone"), Device("iPad"))),
  User("Brian",   List(Device("iPhone"))),
  User("Charles", List(Device("Android"), Device("iPhone"))),
  User("Dennis",  List(Device("iPad"), Device("Android"), Device("iPad"))),
  User("Eric",    Nil)
)

// Map(iPad -> 3, iPhone -> 3, Android -> 2)



// -----------------
// 10. andThenを使ってUNIXパイプのような処理を書いてみよう

val emails = List(
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]"
)

// $ cat emails.txt
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// [email protected]
// $ awk -F@ '{print $2}' emails.txt | sort | uniq -c
//  1 aol.com
//  1 facebook.com
//  3 gmail.com
//  2 hotmail.com
//  1 yahoo.co.jp
//  2 yahoo.com
//

// Map(hotmail.com -> 2, gmail.com -> 3, aol.com -> 1, facebook.com -> 1, yahoo.co.jp -> 1, yahoo.com -> 2)




// -----------------
/*
（回答例）


1.
val list = List("Scala", "http://scala-lang.org", "Java", "http://java.net/", "Haskell", "http://haskell.org/")
list sliding(2,2) map { case e => (e(0), e(1)) } toMap

2.
val list = List(1,2,1,3,2,4,4,2,4,3)
list distinct

3.
val list = List(2,3,0,1,5,4)

list sortWith(_<_) map { i => i * i }
for(i <- list sorted) yield i * i

4.
(for(i <- 1 to 5; j <- 1 to i; k = i*j) yield (i,j,k)).toList

5.
val h = List("name","lang","country")
val ds = List(("Andy","Scala","Japan"),("Brian","Python","America"),("Samir","Java","India"))

println(h.mkString(","))
ds map { d => d.productIterator mkString(",") } foreach println

6.
case class Person(name: String, age: Int)
val people = List(
  Person("Andy",34), 
  Person("Bob",18), 
  Person("Charles",45), 
  Person("Eric",13)
)

val (adults, minors) = people partition { p => p.age > 20 } 

8.
val input = List(1,2,3,"a","3",4)
val square = (a: Any) => a match {
  case i: Int => Some(i*i)
  case _ => None
}

List(1,2,3,"a","3",4) flatMap { i => square(i) }

9.
case class Device(name: String)
case class User(name: String, devices: List[Device])
val users = List(
  User("Andy",    List(Device("iPhone"), Device("iPad"))),
  User("Brian",   List(Device("iPhone"))),
  User("Charles", List(Device("Android"), Device("iPhone"))),
  User("Dennis",  List(Device("iPad"), Device("Android"), Device("iPad"))),
  User("Eric",    Nil)
)

users flatMap { user => user.devices } groupBy { _.name } map { case (name, list) => (name, list.size) }

10.

val emails = List(
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]"
)

val extractDomain = (emails: List[String]) => emails map { case email => email.split("@").tail.head }
val sort = (domains: List[String]) => domains sortWith { _ < _ }
val uniqCount = (domains: List[String]) => domains groupBy { domain => domain } map { case (name, list) => (name, list.size) }

val main = extractDomain andThen sort andThen uniqCount
main(emails)

*/