Scala Cookbook

11.29. Using a Range

Problem

You want to use a Range in a Scala application.

Solution

Ranges are often used to populate data structures, and to iterate over for loops. Ranges provide a lot of power with just a few methods, as shown in these examples:

scala> 1 to 10
res0: scala.collection.immutable.Range.Inclusive =
  Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

scala> 1 until 10
res1: scala.collection.immutable.Range = Range(1, 2, 3, 4, 5, 6, 7, 8, 9)

scala> 1 to 10 by 2
res2: scala.collection.immutable.Range = Range(1, 3, 5, 7, 9)

scala> 'a' to 'c'
res3: collection.immutable.NumericRange.Inclusive[Char] = NumericRange(a, b, c)

You can use ranges to create and populate sequences:

scala> val x = (1 to 10).toList
x: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

scala> val x = (1 to 10).toArray
x: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

scala> val x = (1 to 10).toSet
x: scala.collection.immutable.Set[Int] = Set(5, 10, 1, 6, 9, 2, 7, 3, 8, 4)

Some sequences have a range method in their objects to perform the same function:

scala> val x = Array.range(1, 10)
x: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9)

scala> val x = Vector.range(1, 10)
x: collection.immutable.Vector[Int] = Vector(1, 2, 3, 4, 5, 6, 7, 8, 9)

scala> val x = List.range(1, 10)
x: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9)

scala> val x = List.range(0, 10, 2)
x: List[Int] = List(0, 2, 4, 6, 8)

scala> val x = collection.mutable.ArrayBuffer.range('a', 'd')
x: scala.collection.mutable.ArrayBuffer[Char] = ArrayBuffer(a, b, c)

Ranges ...