charles/scala_parallelism_concurrency
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Test 2

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Kali Live user 2020-03-15 12:02:25 +00:00
parent 9a3514a468
commit 16b6696555
1 changed files with 11 additions and 11 deletions
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22
src/main/scala/kmeans/KMeans.scala
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@ -45,10 +45,9 @@ class KMeans extends KMeansInterface {
}
def classify(points: ParSeq[Point], means: ParSeq[Point]): ParMap[Point, ParSeq[Point]] = {
val meansWithPoints = points.groupBy( p => findClosest(p, means) )
means
.map(m => (m, if (meansWithPoints.contains(m)) List() ++ meansWithPoints(m) else List()))
.toMap
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 {
@ -64,20 +63,21 @@ class KMeans extends KMeansInterface {
}
def update(classified: ParMap[Point, ParSeq[Point]], oldMeans: ParSeq[Point]): ParSeq[Point] = {
oldMeans.map( mean => findAverage(mean, classified(mean)) )
oldMeans.par.map(oldMean => findAverage(oldMean, classified(oldMean)))
}
def converged(eta: Double, oldMeans: ParSeq[Point], newMeans: ParSeq[Point]): Boolean = {
oldMeans
.zip(newMeans)
.map(p => p._1.squareDistance(p._2) <= eta)
.forall( t => t )
(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 freshMints = update(classify(points, means), means)
if (!converged(eta)(means, freshMints)) kMeans(points, freshMints, eta) else freshMints // your implementation need to be tail recursive
val classified = classify(points, means)
val newMeans = update(classified, means)
if (!converged(eta, means, newMeans)) kMeans(points, newMeans, eta) else newMeans
}
}