.gitlab-ci.yml

@@ -25,7 +25,7 @@ grade:
   tags:
     - cs206
   image:
-    name: smarter3/moocs:reactive-actorbintree-2020-04-15
+    name: smarter3/moocs:parprog1-kmeans-2020-02-24-2
     entrypoint: [""]
   allow_failure: true
   before_script:

assignment.sbt

@@ -1,4 +1,9 @@
 // Student tasks (i.e. submit, packageSubmission)
 enablePlugins(StudentTasks)
 
-
+courseraId := ch.epfl.lamp.CourseraId(
+  key = "UJmFEtoIEeWJwRKcpT8ChQ",
+  itemId = "Olt0g",
+  premiumItemId = Some("akLxD"),
+  partId = "mz8iL"
+)

build.sbt

@@ -1,24 +1,13 @@
-course := "reactive"
-assignment := "actorbintree"
-
-testOptions in Test += Tests.Argument(TestFrameworks.JUnit, "-a", "-v", "-s")
-parallelExecution in Test := false
-
-val akkaVersion = "2.6.0"
+course := "parprog1"
+assignment := "kmeans"
 
 scalaVersion := "0.23.0-bin-20200211-5b006fb-NIGHTLY"
-
-scalacOptions ++= Seq(
-  "-feature",
-  "-deprecation",
-  "-encoding", "UTF-8",
-  "-unchecked",
-  "-language:implicitConversions"
-)
-
+scalacOptions ++= Seq("-language:implicitConversions", "-deprecation")
 libraryDependencies ++= Seq(
-  "com.typesafe.akka"        %% "akka-actor"         % akkaVersion,
-  "com.typesafe.akka"        %% "akka-testkit"       % akkaVersion % Test,
-  "com.novocode"             % "junit-interface"     % "0.11"      % Test
+  "com.storm-enroute" %% "scalameter-core" % "0.19",
+  "org.scala-lang.modules" %% "scala-parallel-collections" % "0.2.0",
+  "com.novocode" % "junit-interface" % "0.11" % Test
 ).map(_.withDottyCompat(scalaVersion.value))
-testSuite := "actorbintree.BinaryTreeSuite"
+
+testOptions in Test += Tests.Argument(TestFrameworks.JUnit, "-a", "-v", "-s")
+testSuite := "kmeans.KMeansSuite"

src/main/scala/actorbintree/BinaryTreeSet.scala

@@ -1,189 +0,0 @@
-/**
- * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
- */
-package actorbintree
-
-import akka.actor._
-import scala.collection.immutable.Queue
-
-object BinaryTreeSet {
-
-  trait Operation {
-    def requester: ActorRef
-    def id: Int
-    def elem: Int
-  }
-
-  trait OperationReply {
-    def id: Int
-  }
-
-  /** Request with identifier `id` to insert an element `elem` into the tree.
-    * The actor at reference `requester` should be notified when this operation
-    * is completed.
-    */
-  case class Insert(requester: ActorRef, id: Int, elem: Int) extends Operation
-
-  /** Request with identifier `id` to check whether an element `elem` is present
-    * in the tree. The actor at reference `requester` should be notified when
-    * this operation is completed.
-    */
-  case class Contains(requester: ActorRef, id: Int, elem: Int) extends Operation
-
-  /** Request with identifier `id` to remove the element `elem` from the tree.
-    * The actor at reference `requester` should be notified when this operation
-    * is completed.
-    */
-  case class Remove(requester: ActorRef, id: Int, elem: Int) extends Operation
-
-  /** Request to perform garbage collection */
-  case object GC
-
-  /** Holds the answer to the Contains request with identifier `id`.
-    * `result` is true if and only if the element is present in the tree.
-    */
-  case class ContainsResult(id: Int, result: Boolean) extends OperationReply
-
-  /** Message to signal successful completion of an insert or remove operation. */
-  case class OperationFinished(id: Int) extends OperationReply
-
-}
-
-
-class BinaryTreeSet extends Actor {
-  import BinaryTreeSet._
-  import BinaryTreeNode._
-
-  def createRoot: ActorRef = context.actorOf(BinaryTreeNode.props(0, initiallyRemoved = true))
-
-  var root = createRoot
-
-  // optional
-  var pendingQueue = Queue.empty[Operation]
-
-  // optional
-  def receive = normal
-
-  // optional
-  /** Accepts `Operation` and `GC` messages. */
-  val normal: Receive = {
-    case op:Operation => root ! op
-    case GC => {
-      val newRoot = createRoot;
-      root ! CopyTo(newRoot)
-      context.become(garbageCollecting(newRoot))
-    }
-   }
-
-  // optional
-  /** Handles messages while garbage collection is performed.
-    * `newRoot` is the root of the new binary tree where we want to copy
-    * all non-removed elements into.
-    */
-  def garbageCollecting(newRoot: ActorRef): Receive = {
-    case op:Operation => pendingQueue = pendingQueue.enqueue(op)
-    case CopyFinished =>
-      pendingQueue.foreach(newRoot ! _) //foreach preserves order of a queue (same as dequeueing)
-      root ! PoisonPill //Will also stop all of its children
-      pendingQueue = Queue.empty
-      root = newRoot;
-      context.become(normal)
-    //Ignore GC messages here
-  }
-}
-
-object BinaryTreeNode {
-  trait Position
-
-  case object Left extends Position
-  case object Right extends Position
-
-  case class CopyTo(treeNode: ActorRef)
-  case object CopyFinished
-
-  def props(elem: Int, initiallyRemoved: Boolean) = Props(classOf[BinaryTreeNode],  elem, initiallyRemoved)
-}
-
-class BinaryTreeNode(val elem: Int, initiallyRemoved: Boolean) extends Actor {
-  import BinaryTreeNode._
-  import BinaryTreeSet._
-
-  var subtrees = Map[Position, ActorRef]()
-  var removed = initiallyRemoved
-
-  // optional
-  def receive = normal
-
-  def goDownTo(elem : Int) : Position = if(elem < this.elem) Left else Right
-  // optional
-  /** Handles `Operation` messages and `CopyTo` requests. */
-  val normal: Receive = {
-    case Insert  (requester, id, elem) =>
-      if(elem == this.elem && !removed){
-        requester ! OperationFinished(id)
-      }else{
-        val nextPos = goDownTo(elem)
-        
-        subtrees get nextPos match{
-          case Some(node) => node ! Insert(requester, id, elem)
-          case None => {
-              val newActorSubtree = (nextPos, context.actorOf(BinaryTreeNode.props(elem, false)))
-              subtrees = subtrees + newActorSubtree
-              requester ! OperationFinished(id);
-          }
-        }
-      }
-    case Contains(requester, id, elem) =>
-      if(elem == this.elem && !removed)
-        requester ! ContainsResult(id, true)
-      else{
-        //Need to search subtrees
-        subtrees get goDownTo(elem) match{
-          case Some(node) => node ! Contains(requester, id, elem)
-          case None => requester ! ContainsResult(id, false)
-        }
-      }
-        
-    case Remove  (requester, id, elem) => 
-      if(elem == this.elem && !removed){
-        removed = true
-        requester ! OperationFinished(id)
-      }else{
-        subtrees get goDownTo(elem) match{
-          case Some(node) => node ! Remove(requester, id, elem)
-          case None => requester ! OperationFinished(id) // (elem isn't in the tree)
-        }
-      }
-
-    case CopyTo(newRoot) =>
-      //We are already done, nothing to do
-      if(removed && subtrees.isEmpty) context.parent ! CopyFinished
-      else{
-        if(!removed) newRoot ! Insert(self, elem, elem)
-        subtrees.values foreach(_ ! CopyTo(newRoot)) //Copy subtrees elems
-        //val insertConfirmed = if(removed) true else false, hence we can simply pass removed
-        context.become(copying(subtrees.values.toSet, removed))
-      }
-  }
-
-  // optional
-  /** `expected` is the set of ActorRefs whose replies we are waiting for,
-    * `insertConfirmed` tracks whether the copy of this node to the new tree has been confirmed.
-    */
-  def copying(expected: Set[ActorRef], insertConfirmed: Boolean): Receive = {
-    //To catch the insert of this node into the new tree beeing finished
-    case OperationFinished(_) => {
-      if(expected.isEmpty) context.parent ! CopyFinished
-      else context.become(copying(expected, true))
-    }
-    
-    case CopyFinished => {
-      val newExp = expected-sender
-      if(insertConfirmed && newExp.isEmpty){
-        context.parent ! CopyFinished
-      }else{
-        context.become(copying(newExp, insertConfirmed))
-      }
-    }
-  }
-}

src/main/scala/kmeans/KMeans.scala

@@ -0,0 +1,147 @@
+package kmeans
+
+import scala.annotation.tailrec
+import scala.collection.{Map, Seq, mutable}
+import scala.collection.parallel.CollectionConverters._
+import scala.collection.parallel.{ForkJoinTaskSupport, ParMap, ParSeq}
+import scala.util.Random
+import org.scalameter._
+import java.util.concurrent.ForkJoinPool
+
+class KMeans extends KMeansInterface {
+
+  def generatePoints(k: Int, num: Int): ParSeq[Point] = {
+    val randx = new Random(1)
+    val randy = new Random(3)
+    val randz = new Random(5)
+    (0 until num)
+      .map({ i =>
+        val x = ((i + 1) % k) * 1.0 / k + randx.nextDouble() * 0.5
+        val y = ((i + 5) % k) * 1.0 / k + randy.nextDouble() * 0.5
+        val z = ((i + 7) % k) * 1.0 / k + randz.nextDouble() * 0.5
+        new Point(x, y, z)
+      }).to(mutable.ArrayBuffer).par
+  }
+
+  def initializeMeans(k: Int, points: ParSeq[Point]): ParSeq[Point] = {
+    val rand = new Random(7)
+    (0 until k).map(_ => points(rand.nextInt(points.length))).to(mutable.ArrayBuffer).par
+  }
+
+  def findClosest(p: Point, means: IterableOnce[Point]): Point = {
+    val it = means.iterator
+    assert(it.nonEmpty)
+    var closest = it.next()
+    var minDistance = p.squareDistance(closest)
+    while (it.hasNext) {
+      val point = it.next()
+      val distance = p.squareDistance(point)
+      if (distance < minDistance) {
+        minDistance = distance
+        closest = point
+      }
+    }
+    closest
+  }
+
+  def classify(points: ParSeq[Point], means: ParSeq[Point]): ParMap[Point, ParSeq[Point]] = {
+    val pointsMeanMap = points.par.groupBy(findClosest(_, means))
+    // So iterate over means get (empty) list and return map
+    means.par.map(mean => mean -> pointsMeanMap.getOrElse(mean, ParSeq())).toMap
+  }
+
+  def findAverage(oldMean: Point, points: ParSeq[Point]): Point = if (points.isEmpty) oldMean else {
+    var x = 0.0
+    var y = 0.0
+    var z = 0.0
+    points.seq.foreach { p =>
+      x += p.x
+      y += p.y
+      z += p.z
+    }
+    new Point(x / points.length, y / points.length, z / points.length)
+  }
+
+  def update(classified: ParMap[Point, ParSeq[Point]], oldMeans: ParSeq[Point]): ParSeq[Point] = {
+    oldMeans.par.map(oldMean => findAverage(oldMean, classified(oldMean)))
+  }
+
+  def converged(eta: Double, oldMeans: ParSeq[Point], newMeans: ParSeq[Point]): Boolean = {
+    (oldMeans zip newMeans).forall{
+      case (oldMean, newMean) => oldMean.squareDistance(newMean) <=  eta
+    }
+  }
+
+  @tailrec
+  final def kMeans(points: ParSeq[Point], means: ParSeq[Point], eta: Double): ParSeq[Point] = {
+    val classified = classify(points, means)
+    val newMeans = update(classified, means)
+
+    if (!converged(eta, means, newMeans)) kMeans(points, newMeans, eta) else newMeans
+  }
+}
+
+/** Describes one point in three-dimensional space.
+ *
+ *  Note: deliberately uses reference equality.
+ */
+class Point(val x: Double, val y: Double, val z: Double) {
+  private def square(v: Double): Double = v * v
+  def squareDistance(that: Point): Double = {
+    square(that.x - x)  + square(that.y - y) + square(that.z - z)
+  }
+  private def round(v: Double): Double = (v * 100).toInt / 100.0
+  override def toString = s"(${round(x)}, ${round(y)}, ${round(z)})"
+}
+
+
+object KMeansRunner {
+
+  val standardConfig = config(
+    Key.exec.minWarmupRuns -> 20,
+    Key.exec.maxWarmupRuns -> 40,
+    Key.exec.benchRuns -> 25,
+    Key.verbose -> false
+  ) withWarmer(new Warmer.Default)
+
+  def main(args: Array[String]): Unit = {
+    val kMeans = new KMeans()
+
+    val numPoints = 500000
+    val eta = 0.01
+    val k = 32
+    val points = kMeans.generatePoints(k, numPoints)
+    val means = kMeans.initializeMeans(k, points)
+
+    val seqtime = {
+      val parTasksupport = points.tasksupport
+      val seqPool = new ForkJoinPool(1)
+      val seqTasksupport = new ForkJoinTaskSupport(seqPool)
+      try {
+        points.tasksupport = seqTasksupport
+        means.tasksupport = seqTasksupport
+        standardConfig measure {
+          kMeans.kMeans(points, means, eta)
+        }
+      }
+      finally {
+        points.tasksupport = parTasksupport
+        means.tasksupport = parTasksupport
+        seqPool.shutdown()
+      }
+    }
+
+    val partime = standardConfig measure {
+      kMeans.kMeans(points, means, eta)
+    }
+
+    println(s"sequential time: $seqtime")
+    println(s"parallel time: $partime")
+    println(s"speedup: ${seqtime.value / partime.value}")
+  }
+
+  // Workaround Dotty's handling of the existential type KeyValue
+  implicit def keyValueCoerce[T](kv: (Key[T], T)): KeyValue = {
+    kv.asInstanceOf[KeyValue]
+  }
+}

src/main/scala/kmeans/KMeansInterface.scala

@@ -0,0 +1,15 @@
+package kmeans
+
+import scala.collection.{Map, Seq}
+import scala.collection.parallel.{ParMap, ParSeq}
+
+/**
+ * The interface used by the grading infrastructure. Do not change signatures
+ * or your submission will fail with a NoSuchMethodError.
+ */
+trait KMeansInterface {
+  def classify(points: ParSeq[Point], means: ParSeq[Point]): ParMap[Point, ParSeq[Point]]
+  def update(classified: ParMap[Point, ParSeq[Point]], oldMeans: ParSeq[Point]): ParSeq[Point]
+  def converged(eta: Double, oldMeans: ParSeq[Point], newMeans: ParSeq[Point]): Boolean
+  def kMeans(points: ParSeq[Point], means: ParSeq[Point], eta: Double): ParSeq[Point]
+}

src/main/scala/kmeans/fun/IndexedColors.scala

@@ -0,0 +1,117 @@
+package kmeans
+package fun
+
+import scala.collection.Seq
+import scala.collection.parallel.ParSeq
+import scala.collection.parallel.CollectionConverters._
+
+abstract sealed trait InitialSelectionStrategy
+case object RandomSampling extends InitialSelectionStrategy
+case object UniformSampling extends InitialSelectionStrategy
+case object UniformChoice extends InitialSelectionStrategy
+
+abstract sealed trait ConvergenceStrategy
+case class ConvergedWhenSNRAbove(x: Double) extends ConvergenceStrategy
+case class ConvergedAfterNSteps(n: Int) extends ConvergenceStrategy
+case class ConvergedAfterMeansAreStill(eta: Double) extends ConvergenceStrategy
+
+
+class IndexedColorFilter(initialImage: Img,
+                         colorCount: Int,
+                         initStrategy: InitialSelectionStrategy,
+                         convStrategy: ConvergenceStrategy) extends KMeans {
+
+  private var steps = 0
+
+  val points = imageToPoints(initialImage).par
+  val means = initializeIndex(colorCount, points).par
+
+  /* The work is done here: */
+  private val newMeans = kMeans(points, means, 0.01)
+
+  /* And these are the results exposed */
+  def getStatus() = s"Converged after $steps steps."
+  def getResult() = indexedImage(initialImage, newMeans)
+
+  private def imageToPoints(img: Img): Seq[Point] =
+    for (x <- 0 until img.width; y <- 0 until img.height) yield {
+      val rgba = img(x, y)
+      new Point(red(rgba), green(rgba), blue(rgba))
+    }
+
+  private def indexedImage(img: Img, means: ParSeq[Point]) = {
+    val dst = new Img(img.width, img.height)
+    val pts = collection.mutable.Set[Point]()
+
+    for (x <- 0 until img.width; y <- 0 until img.height) yield {
+      val v = img(x, y)
+      var point = new Point(red(v), green(v), blue(v))
+      point = findClosest(point, means)
+      pts += point
+      dst(x, y) = rgba(point.x, point.y, point.z, 1d)
+    }
+
+    dst
+  }
+
+  private def initializeIndex(numColors: Int, points: ParSeq[Point]): Seq[Point] = {
+    val initialPoints: Seq[Point] =
+      initStrategy match {
+        case RandomSampling =>
+          val d: Int = points.size / numColors
+          (0 until numColors) map (idx => points(d * idx))
+        case UniformSampling =>
+          val sep: Int = 32
+          (for (r <- 0 until 255 by sep; g <- 0 until 255 by sep; b <- 0 until 255 by sep) yield {
+            def inside(p: Point): Boolean =
+              (p.x >= (r.toDouble / 255)) &&
+              (p.x <= ((r.toDouble + sep) / 255)) &&
+              (p.y >= (g.toDouble / 255)) &&
+              (p.y <= ((g.toDouble + sep) / 255)) &&
+              (p.z >= (b.toDouble / 255)) &&
+              (p.z <= ((b.toDouble + sep) / 255))
+
+            val pts = points.filter(inside(_))
+            val cnt = pts.size * 3 * numColors / points.size
+            if (cnt >= 1) {
+              val d = pts.size / cnt
+              (0 until cnt) map (idx => pts(d * idx))
+            } else
+              Seq()
+          }).flatten
+        case UniformChoice =>
+          val d: Int = math.max(1, (256 / math.cbrt(numColors.toDouble).ceil).toInt)
+          for (r <- 0 until 256 by d; g <- 0 until 256 by d; b <- 0 until 256 by d) yield
+            new Point(r.toDouble / 256,g.toDouble / 256, b.toDouble / 256)
+      }
+
+    val d2 = initialPoints.size.toDouble / numColors
+    (0 until numColors) map (idx => initialPoints((idx * d2).toInt))
+  }
+
+  private def computeSNR(points: ParSeq[Point], means: ParSeq[Point]): Double = {
+    var sound = 0.0
+    var noise = 0.0
+
+    for (point <- points) {
+      import math.{pow, sqrt}
+      val closest = findClosest(point, means)
+      sound += sqrt(pow(point.x, 2) + pow(point.y, 2) + pow(point.z, 2))
+      noise += sqrt(pow(point.x - closest.x, 2) + pow(point.y - closest.y, 2) + pow(point.z - closest.z, 2))
+    }
+    sound/noise
+  }
+
+  override def converged(eta: Double, oldMeans: ParSeq[Point], newMeans: ParSeq[Point]): Boolean = {
+    steps += 1
+    convStrategy match {
+      case ConvergedAfterNSteps(n) =>
+        steps >= n
+      case ConvergedAfterMeansAreStill(eta) =>
+        super.converged(eta, oldMeans, newMeans)
+      case ConvergedWhenSNRAbove(snr_desired) =>
+        val snr_computed = computeSNR(points.par, newMeans)
+        snr_computed >= snr_desired
+    }
+  }
+}

src/main/scala/kmeans/fun/PhotoCanvas.scala

@@ -0,0 +1,95 @@
+package kmeans
+package fun
+
+import java.awt._
+import java.awt.event._
+import java.awt.image._
+import java.io._
+import javax.imageio._
+import javax.swing._
+import javax.swing.event._
+
+class PhotoCanvas extends JComponent {
+
+  var imagePath: Option[String] = None
+
+  var image = loadEPFLImage()
+
+  val timerDelay = 100
+  val timer =
+    new Timer(timerDelay, new ActionListener() {
+      def actionPerformed(e: ActionEvent): Unit = repaint()
+    })
+
+  override def getPreferredSize = {
+    new Dimension(image.width, image.height)
+  }
+
+  private def loadEPFLImage(): Img = {
+    val stream = this.getClass.getResourceAsStream("/kmeans/epfl-view.jpg")
+    try {
+      loadImage(stream)
+    } finally {
+      stream.close()
+    }
+  }
+
+  private def loadFileImage(path: String): Img = {
+    val stream = new FileInputStream(path)
+    try {
+      loadImage(stream)
+    } finally {
+      stream.close()
+    }
+  }
+
+  private def loadImage(inputStream: InputStream): Img = {
+    val bufferedImage = ImageIO.read(inputStream)
+    val width = bufferedImage.getWidth
+    val height = bufferedImage.getHeight
+    val img = new Img(width, height)
+    for (x <- 0 until width; y <- 0 until height)
+      img(x, y) = bufferedImage.getRGB(x, y)
+    img
+  }
+
+  def reload(): Unit = {
+    image = imagePath match {
+      case Some(path) => loadFileImage(path)
+      case None => loadEPFLImage()
+    }
+    repaint()
+  }
+
+  def loadFile(path: String): Unit = {
+    imagePath = Some(path)
+    reload()
+  }
+
+  def saveFile(path: String): Unit = {
+    reload()
+    val stream = new FileOutputStream(path)
+    val bufferedImage = new BufferedImage(image.width, image.height, BufferedImage.TYPE_INT_ARGB)
+    for (x <- 0 until image.width; y <- 0 until image.height) bufferedImage.setRGB(x, y, image(x, y))
+    ImageIO.write(bufferedImage, "png", stream)
+  }
+
+  def applyIndexedColors(colorCount: Int, initStrategy: InitialSelectionStrategy, convStrategy: ConvergenceStrategy): String = {
+    val filter = new IndexedColorFilter(image, colorCount, initStrategy, convStrategy)
+    image = filter.getResult()
+    repaint()
+    filter.getStatus()
+  }
+
+  override def paintComponent(gcan: Graphics) = {
+    super.paintComponent(gcan)
+
+    val width = image.width
+    val height = image.height
+    val bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB)
+    for (x <- 0 until width; y <- 0 until height) bufferedImage.setRGB(x, y, image(x, y))
+
+    gcan.drawImage(bufferedImage, 0, 0, null)
+  }
+
+}

src/main/scala/kmeans/fun/ScalaShop.scala

@@ -0,0 +1,218 @@
+package kmeans
+package fun
+
+import java.awt._
+import java.awt.event._
+import javax.swing._
+import javax.swing.event._
+import scala.collection.mutable.ArrayBuffer
+import scala.reflect.ClassTag
+import org.scalameter._
+
+object ScalaShop {
+
+  class ScalaShopFrame extends JFrame("ScalaShop\u2122") {
+    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE)
+    setSize(800, 500)
+    setLayout(new BorderLayout)
+
+    val rightpanel = new JPanel
+    rightpanel.setBorder(BorderFactory.createEtchedBorder(border.EtchedBorder.LOWERED))
+    rightpanel.setLayout(new BorderLayout)
+    add(rightpanel, BorderLayout.EAST)
+
+    val allControls = new JPanel
+    allControls.setLayout(new BoxLayout(allControls, BoxLayout.Y_AXIS))
+    rightpanel.add(allControls, BorderLayout.NORTH)
+
+    // Color count selection
+    val colorControls = new JPanel
+    colorControls.setLayout(new GridLayout(0, 2))
+    allControls.add(colorControls)
+
+    val colorCountLabel = new JLabel("Colors")
+    colorControls.add(colorCountLabel)
+
+    val colorCountSpinner = new JSpinner(new SpinnerNumberModel(32, 16, 512, 16))
+    colorControls.add(colorCountSpinner)
+
+    // Initial selection
+    val initSelectionControls = new JPanel
+    initSelectionControls.setLayout(new GridLayout(0, 1))
+    allControls.add(initSelectionControls)
+
+    val initialSelectionGroup = new ButtonGroup()
+
+    val initSelectionLabel = new JLabel("Initial Color Selection:")
+    initSelectionControls.add(initSelectionLabel)
+
+    val uniformSamplingButton = new JRadioButton("Uniform Sampling")
+    uniformSamplingButton.setSelected(true);
+    initSelectionControls.add(uniformSamplingButton)
+
+    val randomSamplingButton = new JRadioButton("Random Sampling")
+    initSelectionControls.add(randomSamplingButton)
+
+    val uniformChoiceButton = new JRadioButton("Uniform Choice")
+    initSelectionControls.add(uniformChoiceButton)
+
+    initialSelectionGroup.add(randomSamplingButton)
+    initialSelectionGroup.add(uniformSamplingButton)
+    initialSelectionGroup.add(uniformChoiceButton)
+
+    // Initial means selection
+    val convergenceControls = new JPanel
+    convergenceControls.setLayout(new BoxLayout(convergenceControls, BoxLayout.Y_AXIS))
+    allControls.add(convergenceControls)
+
+    val convergenceGroup = new ButtonGroup()
+
+    val convergenceLabel = new JLabel("Convergence criteria:")
+    initSelectionControls.add(convergenceLabel)
+
+    val criteriaControls = new JPanel
+    criteriaControls.setLayout(new GridLayout(0, 2))
+    convergenceControls.add(criteriaControls)
+
+    val stepConvergenceButton = new JRadioButton("Steps")
+    criteriaControls.add(stepConvergenceButton)
+
+    val stepCountSpinner = new JSpinner(new SpinnerNumberModel(5, 1, 50, 1))
+    criteriaControls.add(stepCountSpinner)
+
+    val etaConvergenceButton = new JRadioButton("Eta")
+    etaConvergenceButton.setSelected(true);
+    criteriaControls.add(etaConvergenceButton)
+
+    val etaCountSpinner = new JSpinner(new SpinnerNumberModel(0.001, 0.00001, 0.01, 0.00001))
+    criteriaControls.add(etaCountSpinner)
+
+    val snrConvergenceButton = new JRadioButton("Sound-to-noise")
+    criteriaControls.add(snrConvergenceButton)
+
+    val snrCountSpinner = new JSpinner(new SpinnerNumberModel(40, 10, 80, 1))
+    criteriaControls.add(snrCountSpinner)
+
+    convergenceGroup.add(stepConvergenceButton)
+    convergenceGroup.add(etaConvergenceButton)
+    convergenceGroup.add(snrConvergenceButton)
+
+    // Action Buttons
+    val actionControls = new JPanel
+    actionControls.setLayout(new GridLayout(0, 2))
+    allControls.add(actionControls)
+
+    val stepbutton = new JButton("Apply filter")
+    stepbutton.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        var status = ""
+        val time = measure {
+          status = canvas.applyIndexedColors(getColorCount, getInitialSelectionStrategy, getConvergenceStragegy)
+        }
+        updateInformationBox(status, time.value)
+      }
+    })
+    actionControls.add(stepbutton)
+
+    val clearButton = new JButton("Reload")
+    clearButton.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        canvas.reload()
+      }
+    })
+    actionControls.add(clearButton)
+
+    val info = new JTextArea("              ")
+    info.setBorder(BorderFactory.createLoweredBevelBorder)
+    rightpanel.add(info, BorderLayout.SOUTH)
+
+    val mainMenuBar = new JMenuBar()
+
+    val fileMenu = new JMenu("File")
+    val openMenuItem = new JMenuItem("Open...")
+    openMenuItem.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        val fc = new JFileChooser()
+        if (fc.showOpenDialog(ScalaShopFrame.this) == JFileChooser.APPROVE_OPTION) {
+          canvas.loadFile(fc.getSelectedFile.getPath)
+        }
+      }
+    })
+    fileMenu.add(openMenuItem)
+    val saveMenuItem = new JMenuItem("Save...")
+    saveMenuItem.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        val fc = new JFileChooser("epfl-view.png")
+        if (fc.showSaveDialog(ScalaShopFrame.this) == JFileChooser.APPROVE_OPTION) {
+          canvas.saveFile(fc.getSelectedFile.getPath)
+        }
+      }
+    })
+    fileMenu.add(saveMenuItem)
+    val exitMenuItem = new JMenuItem("Exit")
+    exitMenuItem.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        sys.exit(0)
+      }
+    })
+    fileMenu.add(exitMenuItem)
+
+    mainMenuBar.add(fileMenu)
+
+    val helpMenu = new JMenu("Help")
+    val aboutMenuItem = new JMenuItem("About")
+    aboutMenuItem.addActionListener(new ActionListener {
+      def actionPerformed(e: ActionEvent): Unit = {
+        JOptionPane.showMessageDialog(null, "ScalaShop, the ultimate image manipulation tool\nBrought to you by EPFL, 2015")
+      }
+    })
+    helpMenu.add(aboutMenuItem)
+
+    mainMenuBar.add(helpMenu)
+
+    setJMenuBar(mainMenuBar)
+
+    val canvas = new PhotoCanvas
+
+    val scrollPane = new JScrollPane(canvas)
+
+    add(scrollPane, BorderLayout.CENTER)
+    setVisible(true)
+
+    def updateInformationBox(status: String, time: Double): Unit = {
+      info.setText(s"$status\nTime: ${time.toInt} ms.")
+    }
+
+    def getColorCount: Int =
+      colorCountSpinner.getValue.asInstanceOf[Int]
+
+    def getInitialSelectionStrategy: InitialSelectionStrategy =
+      if (randomSamplingButton.isSelected())
+        RandomSampling
+      else if (uniformSamplingButton.isSelected())
+        UniformSampling
+      else
+        UniformChoice
+
+    def getConvergenceStragegy: ConvergenceStrategy =
+      if (stepConvergenceButton.isSelected())
+        ConvergedAfterNSteps(stepCountSpinner.getValue.asInstanceOf[Int])
+      else if (etaConvergenceButton.isSelected())
+        ConvergedAfterMeansAreStill(etaCountSpinner.getValue.asInstanceOf[Double])
+      else
+        ConvergedWhenSNRAbove(snrCountSpinner.getValue.asInstanceOf[Int])
+  }
+
+  try {
+    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName())
+  } catch {
+    case _: Exception => println("Cannot set look and feel, using the default one.")
+  }
+
+  val frame = new ScalaShopFrame
+
+  def main(args: Array[String]): Unit = {
+    frame.repaint()
+  }
+
+}

src/main/scala/kmeans/fun/package.scala

@@ -0,0 +1,41 @@
+package kmeans
+
+package object fun {
+
+  /** The value of every pixel is represented as a 32 bit integer. */
+  type RGBA = Int
+
+  /** Returns the alpha component. */
+  def alpha(c: RGBA): Double = ((0xff000000 & c) >>> 24).toDouble / 256
+
+  /** Returns the red component. */
+  def red(c: RGBA): Double = ((0x00ff0000 & c) >>> 16).toDouble / 256
+
+  /** Returns the green component. */
+  def green(c: RGBA): Double = ((0x0000ff00 & c) >>> 8).toDouble / 256
+
+  /** Returns the blue component. */
+  def blue(c: RGBA): Double = ((0x000000ff & c) >>> 0).toDouble / 256
+
+  /** Used to create an RGBA value from separate components. */
+  def rgba(r: Double, g: Double, b: Double, a: Double): RGBA = {
+    (clamp((a * 256).toInt, 0, 255) << 24) |
+    (clamp((r * 256).toInt, 0, 255) << 16) |
+    (clamp((g * 256).toInt, 0, 255) <<  8) |
+    (clamp((b * 256).toInt, 0, 255) <<  0)
+  }
+
+  /** Restricts the integer into the specified range. */
+  def clamp(v: Int, min: Int, max: Int): Int = {
+    if (v < min) min
+    else if (v > max) max
+    else v
+  }
+
+  /** Image is a two-dimensional matrix of pixel values. */
+  class Img(val width: Int, val height: Int, private val data: Array[RGBA]) {
+    def this(w: Int, h: Int) = this(w, h, new Array(w * h))
+    def apply(x: Int, y: Int): RGBA = data(y * width + x)
+    def update(x: Int, y: Int, c: RGBA): Unit = data(y * width + x) = c
+  }
+}

src/test/scala/actorbintree/BinaryTreeSuite.scala

@@ -1,126 +0,0 @@
-/**
- * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
- */
-package actorbintree
-
-import akka.actor.{ActorRef, ActorSystem, Props, actorRef2Scala, scala2ActorRef}
-import akka.testkit.{ImplicitSender, TestKit, TestProbe}
-import org.junit.Test
-import org.junit.Assert._
-
-import scala.util.Random
-import scala.concurrent.duration._
-
-class BinaryTreeSuite extends TestKit(ActorSystem("BinaryTreeSuite")) with ImplicitSender {
-
-  import actorbintree.BinaryTreeSet._
-
-  def receiveN(requester: TestProbe, ops: Seq[Operation], expectedReplies: Seq[OperationReply]): Unit =
-    requester.within(5.seconds) {
-      val repliesUnsorted = for (i <- 1 to ops.size) yield try {
-        requester.expectMsgType[OperationReply]
-      } catch {
-        case ex: Throwable if ops.size > 10 => sys.error(s"failure to receive confirmation $i/${ops.size}\n$ex")
-        case ex: Throwable                  => sys.error(s"failure to receive confirmation $i/${ops.size}\nRequests:" + ops.mkString("\n    ", "\n     ", "") + s"\n$ex")
-      }
-      val replies = repliesUnsorted.sortBy(_.id)
-      if (replies != expectedReplies) {
-        val pairs = (replies zip expectedReplies).zipWithIndex filter (x => x._1._1 != x._1._2)
-        fail("unexpected replies:" + pairs.map(x => s"at index ${x._2}: got ${x._1._1}, expected ${x._1._2}").mkString("\n    ", "\n    ", ""))
-      }
-    }
-
-  def verify(probe: TestProbe, ops: Seq[Operation], expected: Seq[OperationReply]): Unit = {
-    val topNode = system.actorOf(Props[BinaryTreeSet])
-
-    ops foreach { op =>
-      topNode ! op
-    }
-
-    receiveN(probe, ops, expected)
-    // the grader also verifies that enough actors are created
-  }
-
-  @Test def `proper inserts and lookups (5pts)`(): Unit = {
-    val topNode = system.actorOf(Props[BinaryTreeSet])
-
-    topNode ! Contains(testActor, id = 1, 1)
-    expectMsg(ContainsResult(1, false))
-
-    topNode ! Insert(testActor, id = 2, 1)
-    topNode ! Contains(testActor, id = 3, 1)
-
-    expectMsg(OperationFinished(2))
-    expectMsg(ContainsResult(3, true))
-    ()
-  }
-
-  @Test def `instruction example (5pts)`(): Unit = {
-    val requester = TestProbe()
-    val requesterRef = requester.ref
-    val ops = List(
-      Insert(requesterRef, id=100, 1),
-      Contains(requesterRef, id=50, 2),
-      Remove(requesterRef, id=10, 1),
-      Insert(requesterRef, id=20, 2),
-      Contains(requesterRef, id=80, 1),
-      Contains(requesterRef, id=70, 2)
-    )
-
-    val expectedReplies = List(
-      OperationFinished(id=10),
-      OperationFinished(id=20),
-      ContainsResult(id=50, false),
-      ContainsResult(id=70, true),
-      ContainsResult(id=80, false),
-      OperationFinished(id=100)
-    )
-
-    verify(requester, ops, expectedReplies)
-  }
-
-
-  @Test def `behave identically to built-in set (includes GC) (40pts)`(): Unit = {
-    val rnd = new Random()
-    def randomOperations(requester: ActorRef, count: Int): Seq[Operation] = {
-      def randomElement: Int = rnd.nextInt(100)
-      def randomOperation(requester: ActorRef, id: Int): Operation = rnd.nextInt(4) match {
-        case 0 => Insert(requester, id, randomElement)
-        case 1 => Insert(requester, id, randomElement)
-        case 2 => Contains(requester, id, randomElement)
-        case 3 => Remove(requester, id, randomElement)
-      }
-
-      for (seq <- 0 until count) yield randomOperation(requester, seq)
-    }
-
-    def referenceReplies(operations: Seq[Operation]): Seq[OperationReply] = {
-      var referenceSet = Set.empty[Int]
-      def replyFor(op: Operation): OperationReply = op match {
-        case Insert(_, seq, elem) =>
-          referenceSet = referenceSet + elem
-          OperationFinished(seq)
-        case Remove(_, seq, elem) =>
-          referenceSet = referenceSet - elem
-          OperationFinished(seq)
-        case Contains(_, seq, elem) =>
-          ContainsResult(seq, referenceSet(elem))
-      }
-
-      for (op <- operations) yield replyFor(op)
-    }
-
-    val requester = TestProbe()
-    val topNode = system.actorOf(Props[BinaryTreeSet])
-    val count = 1000
-
-    val ops = randomOperations(requester.ref, count)
-    val expectedReplies = referenceReplies(ops)
-
-    ops foreach { op =>
-      topNode ! op
-      if (rnd.nextDouble() < 0.1) topNode ! GC
-    }
-    receiveN(requester, ops, expectedReplies)
-  }
-}

src/test/scala/kmeans/KMeansSuite.scala

@@ -0,0 +1,28 @@
+package kmeans
+
+import java.util.concurrent._
+import scala.collection.{mutable, Map, Seq}
+import scala.collection.parallel.{ParMap, ParSeq}
+import scala.collection.parallel.CollectionConverters._
+import scala.math._
+import org.junit._
+import org.junit.Assert.assertEquals
+
+class KMeansSuite {
+  object KM extends KMeans
+  import KM._
+
+  def checkParClassify(points: ParSeq[Point], means: ParSeq[Point], expected: ParMap[Point, ParSeq[Point]]): Unit = {
+    assertEquals(s"classify($points, $means) should equal to $expected", expected, classify(points, means))
+  }
+
+  @Test def `'classify' should work for empty 'points' and empty 'means'`: Unit = {
+    val points: ParSeq[Point] = IndexedSeq().par
+    val means: ParSeq[Point] = IndexedSeq().par
+    val expected = ParMap[Point, ParSeq[Point]]()
+    checkParClassify(points, means, expected)
+  }
+
+}
+
+