ScalaCollectionsTransform.scala

package PlayGround

object ScalaCollectionsTransform {

  val evens = List(2,4,6)
  val odds = List(1,3,5)
  val a = "foo bar baz"
  val foo = "foo"
  val bar = "bar"
  val names = List("Al","Chistina","Kim")
  val firstTen = (1 to 10).toList
  val fiveToFifteen = (5 to 15).toList

  ///2) Transformer and reduction methods
  evens ++ odds          // List(2, 4, 6, 1, 3, 5)
  evens +: odds         // List(2, 4, 6, 1, 3, 5)
  0 +: evens             // List(0, 2, 4, 6)
  odds :+ 7              // List(1, 3, 5, 7)
  0 :: evens             // List(0, 2, 4, 6)
  evens :: odds          // List(List(2, 4, 6), 1, 3, 5)
  evens ::: odds         // List(2, 4, 6, 1, 3, 5)
  (0 /: evens)(_ + _)    // 12
  (evens :\ 0)(_ + _)    // 12

  // collect and collectFirst take a partial function
  firstTen.collect{case x if x % 2 == 0 => x}   // List(2, 4, 6, 8, 10)
  firstTen.collectFirst{case x if x > 1 => x}   // Some(2)

  a.diff("foo")                      // " bar baz"
  a.distinct                         // "fo barz"

  names.flatten                      // List(A, l, C, h, r, i, s, t, i, n, a, K, i, m)
  names.flatMap(_.toUpperCase)       // List(A, L, C, H, R, I, S, T, I, N, A, K, I, M)

  firstTen.groupBy(_ > 5)            // Map(false -> List(1, 2, 3, 4, 5), true -> List(6, 7, 8, 9, 10))
  firstTen.grouped(2)                // Iterator[List[Int]] = non-empty iterator
  firstTen.grouped(2).toList         // List(List(1, 2), List(3, 4), List(5, 6), List(7, 8), List(9, 10))
  firstTen.grouped(5).toList         // List(List(1, 2, 3, 4, 5), List(6, 7, 8, 9, 10))

  firstTen.indices                   // Range(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
  "foo".indices                      // Range(0, 1, 2)

  firstTen.intersect(fiveToFifteen)                  // List(5, 6, 7, 8, 9, 10)

  a.map(_.toUpper)                   // FOO BAR BAZ
  10.byteValue()
  a.mkString(",")                    // f,o,o, ,b,a,r, ,b,a,z
  a.mkString("->", ",", "<-")        // ->f,o,o, ,b,a,r, ,b,a,z<-

  a.par                              // a parallel array, ParArray(f, o, o,  , b, a, r,  , b, a, z)
  a.partition(_ > 'e')               // (foorz, " ba ba")  // a Tuple2
  firstTen.partition(_ > 5)          // (List(6, 7, 8, 9, 10),List(1, 2, 3, 4, 5))

  a.replace('o', 'x')                // fxx bar baz
  a.replace("o", "x")                // fxx bar baz
  a.replaceAll("o", "x")             // fxx bar baz
  a.replaceFirst("o", "x")           // fxo bar baz
  firstTen.reverse                   // List(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)

  // (more on scan, scanLeft, and scanRight below)
  Seq(1,2,3,4,5).scan(1)(_ + _)         // List(1, 2, 4, 7, 11, 16)
  Seq(1,2,3,4,5).scanLeft(1)(_ + _)     // List(1, 2, 4, 7, 11, 16)
  Seq(1,2,3,4,5).scanRight(1)(_ + _)    // List(16, 15, 13, 10, 6, 1)

  a.slice(0,5)                       // foo b
  a.slice(2,9)                       // o bar b

  firstTen.sliding(2)                // Iterator[List[Int]] = non-empty iterator
  firstTen.sliding(2).toList         // List(List(1, 2), List(2, 3), List(3, 4), List(4, 5), List(5, 6), List(6, 7), List(7, 8), List(8, 9), List(9, 10))
  firstTen.sliding(4).toList         // List(List(1, 2, 3, 4), List(2, 3, 4, 5), List(3, 4, 5, 6), List(4, 5, 6, 7), List(5, 6, 7, 8), List(6, 7, 8, 9), List(7, 8, 9, 10))
  firstTen.sliding(2,2).toList       // List(List(1, 2), List(3, 4), List(5, 6), List(7, 8), List(9, 10))
  firstTen.sliding(2,3).toList       // List(List(1, 2), List(4, 5), List(7, 8), List(10))
  firstTen.sliding(2,4).toList       // List(List(1, 2), List(5, 6), List(9, 10))

  a.sortWith(_ < _)                  // "  aabbfoorz"
  a.sortWith(_ > _)                  // "zroofbbaa  "
  a.sorted                           // "  aabbfoorz"

  firstTen.span(_ < 5)               // (List(1, 2, 3, 4),List(5, 6, 7, 8, 9, 10))
  a.split(" ")                       // Array(foo, bar, baz)
  a.splitAt(3)                       // (foo," bar baz")
  firstTen.startsWith(Seq(1,2))      // true

  a.take(3)                          // foo
  a.takeRight(3)                     // baz
  a.takeWhile(_ != 'r')              // foo ba
  a.toArray                          // Array(f, o, o,  , b, a, r,  , b, a, z)
  a.toBuffer                         // ArrayBuffer(f, o, o,  , b, a, r,  , b, a, z)
  a.toList                           // List(f, o, o,  , b, a, r,  , b, a, z)
  Seq(1,1,2,2,3,3).toSet             // Set(1, 2, 3)
  firstTen.toStream                  // scala.collection.immutable.Stream[Int] = Stream(1, ?)
  a.toLowerCase                      // foo bar baz
  a.toUpperCase                      // FOO BAR BAZ
  a.toVector                         // Vector(f, o, o,  , b, a, r,  , b, a, z)
  a.trim                             // "foo bar baz"

  evens.union(odds)                  // List(2, 4, 6, 1, 3, 5)

  Seq(1,2,3).updated(0,10)           // List(10, 2, 3)

  firstTen.view                      // scala.collection.SeqView[Int,List[Int]] = SeqView(...)

  a.zip(0 to 10)                                // Vector((f,10), (o,11), (o,12), ( ,13), (b,14), (a,15), (r,16), ( ,17), (b,18), (a,19), (z,20))
  Seq(1,2,3).zipAll(Seq('a', 'b'), 0, 'z')      // List((1,a), (2,b), (3,z))
  Seq(1,2).zipAll(Seq('a', 'b', 'c'), 0, 'z')   // List((1,a), (2,b), (0,c))
  a.zipWithIndex

}