Scala maps

maps.scala

//create a map
val cars = Map("james" -> "BMW", "ike" -> "Infiniti", "stephen" -> "Buick")

//create a map from an Array
//Scala does not provide a convenience method to do this... :(
val carArray = Array("james", "BMW", "ike", "Infiniti", "stephen", "Buick")
val cars = carArray.grouped(2).toList.map(c => (c.head,c.last)).toMap

//mapping over a map
//transform all string keys to symbols (interned strings)
Map("name" -> "James", "job" -> "consultant", "age" -> "28").map { keyAndValue =>
  val (key, value) = keyAndValue
  (Symbol(key),value)
}

//looking up values in a map
val urls = Map("google" -> "http://google.com", "twitter" -> "http://twitter.com")
println(urls("twitter"))

//add an entry to an immutable map
val husbandsAndWives = Map("james" -> "ashley", "pat" -> "lauren", "david" -> "jenny")
val newHusbandsAndWives = husbandsAndWives.updated("ram", "mani")

//add an entry to a mutable map
import collection.mutable
val husbandsAndWives = mutable.Map("james" -> "ashley", "pat" -> "lauren", "david" -> "jenny")
val newHusbandsAndWives = husbandsAndWives("ram") = "mani"