encode (x,y) coordinates in a single int / published by https://github.com/dacr/code-examples-manager #5b9dcda7-194a-4d1d-8711-355c59a4f8da/9e067961ee5163c9e48e11f643920a2e2265f6c8

algo-coordinates-encoding.sc

// summary : encode (x,y) coordinates in a single int
// keywords : scala, coordinates, conversions, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 5b9dcda7-194a-4d1d-8711-355c59a4f8da
// created-on : 2020-05-27T12:29:46Z
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.5.2"
//> using dep "org.scalatest::scalatest:3.2.19"
//> using objectWrapper
// ---------------------

import org.scalatest._, flatspec._, matchers._

trait Encoding {
  type Coord = (Int, Int)
  type Position = Int

  val width: Int
  val height: Int

  final def coord(x: Int, y: Int): Coord = (x, y)

  final def coord2pos(x: Int, y: Int): Position = y * width + x

  final def coord2pos(coord: Coord): Position = coord match {
    case (x, y) => y * width + x
  }

  final def pos2coord(pos: Position): Coord = (pos % width, pos / width)

}


class TranscodingTest extends AnyFlatSpec with should.Matchers {
  override def suiteName: String = "TranscodingTest"

  val simple = new Encoding {
    override val width = 100
    override val height = 10
  }

  import simple._

  "Encoding" should "encode x,y coordinate into single int value" in {
    coord2pos(0, 0) shouldBe 0
    coord2pos(9, 0) shouldBe 9
    coord2pos(0, 1) shouldBe 100
    coord2pos(width - 1, height - 1) shouldBe width * height - 1
  }

  it should "decode int encoded position into (x,y) coordinates" in {
    pos2coord(100) shouldBe(0, 1)
    pos2coord(width * height - 1) shouldBe(width - 1, height - 1)
  }

}

org.scalatest.tools.Runner.main(Array("-oDF", "-s", classOf[TranscodingTest].getName))