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  1. import scala.math.Numeric
  2. import scala.reflect.ClassTag
  3.  
  4. trait ScalesBy[A, B] {
  5. 	def scale(value: A, scale: B): A
  6. }
  7.  
  8. object ScalesByInstances {
  9.   implicit val scalesIntByInt = new ScalesBy[Int, Int] {
  10.     def scale(value: Int, scale: Int) = value * scale  
  11.   }
  12.   implicit val scalesIntByDouble = new ScalesBy[Int, Double] {
  13.     def scale(value: Int, scale: Double) = (value.toDouble * scale).toInt  
  14.   }
  15.   implicit val scalesDoubleByDouble = new ScalesBy[Double, Double] {
  16.     def scale(value: Double, scale: Double) = value * scale  
  17.   }
  18.   implicit val scalesDoubleByInt = new ScalesBy[Double, Int] {
  19.     def scale(value: Double, scale: Int) = value * scale  
  20.   }
  21.   // TODO: Provide more instances
  22. }
  23.  
  24. class Matrix[A](val rowsCount: Int, val columnsCount: Int)
  25. 		(implicit numOps: Numeric[A], classTag: ClassTag[A]) {
  26.  
  27. 	private[this] val data = new Array[A](rowsCount * columnsCount)
  28.  
  29. 	def apply(coords: (Int, Int)) = {
  30. 		val (row, column) = coords
  31. 		data(row * columnsCount + column)
  32. 	}
  33.  
  34. 	def update(coords: (Int, Int), newVal: A) = {
  35. 		val (row, column) = coords
  36. 		data.update(row * columnsCount + column, newVal)
  37. 	}
  38.  
  39. 	def scaledBy[B](scale: B)(implicit scalesBy: ScalesBy[A, B]) = {
  40. 	  val result = new Matrix(rowsCount, columnsCount)
  41. 	  for (r <- 0 until rowsCount; c <- 0 until columnsCount) {
  42. 	    val cell = apply((r, c))		
  43.         val scaledCell = scalesBy.scale(cell, scale)
  44.         result.update((r, c), scaledCell)
  45.       }		
  46.       result	
  47. 	}
  48. }
  49.  
  50. object Main {
  51.   import ScalesByInstances._
  52.  
  53.   def main(args: Array[String]) = {
  54. 	// your code goes here
  55.     val intMx = new Matrix[Int](3, 2)
  56.     val doubleMx = new Matrix[Double](3, 2)
  57.     intMx((1, 2)) = 3
  58.     doubleMx((1, 2)) = 3
  59.     println("Int cell before: " + intMx((1, 2)))
  60.     println("Double cell before: " + doubleMx((1, 2)))
  61.     val scaledIntMx = intMx.scaledBy(2.5)
  62.     println("Int cell scaled by 2.5: " + scaledIntMx((1, 2)))
  63.     val scaledDoubleMx = doubleMx.scaledBy(2.5)
  64.     println("Double cell scaled by 2.5: " + scaledDoubleMx((1, 2)))	
  65.   }
  66. }
Success #stdin #stdout 0.33s 322240KB
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Int cell before: 3
Double cell before: 3.0
Int cell scaled by 2.5: 7
Double cell scaled by 2.5: 7.5
https://ideone.com/SHd9XQ
language:
Scala (scala 2.12.8)
created:
9 years ago
visibility:
public

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