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refactor kmeans variables names

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This commit is contained in:
Arkadiusz Kondas 2016-05-02 14:02:00 +02:00
parent 5950af6072
commit abd3b38490
2 changed files with 16 additions and 54 deletions
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2
src/Phpml/Clustering/KMeans.php
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@ -51,7 +51,7 @@ class KMeans implements Clusterer
}
$clusters = [];
foreach ($space->solve($this->clustersNumber, $this->initialization) as $cluster) {
foreach ($space->cluster($this->clustersNumber, $this->initialization) as $cluster) {
$clusters[] = $cluster->getPoints();
}

68
src/Phpml/Clustering/KMeans/Space.php
View File

@ -125,81 +125,51 @@ class Space extends SplObjectStorage
}
/**
* @param $nbClusters
* @param int $seed
* @param null $iterationCallback
* @param int $clustersNumber
* @param int $initMethod
*
* @return array|Cluster[]
*/
public function solve($nbClusters, $seed = KMeans::INIT_RANDOM, $iterationCallback = null)
public function cluster(int $clustersNumber, int $initMethod = KMeans::INIT_RANDOM)
{
if ($iterationCallback && !is_callable($iterationCallback)) {
throw new InvalidArgumentException('invalid iteration callback');
}
$clusters = $this->initializeClusters($clustersNumber, $initMethod);
// initialize K clusters
$clusters = $this->initializeClusters($nbClusters, $seed);
// there's only one cluster, clusterization has no meaning
if (count($clusters) == 1) {
return $clusters[0];
}
// until convergence is reached
do {
$iterationCallback && $iterationCallback($this, $clusters);
} while ($this->iterate($clusters));
} while (!$this->iterate($clusters));
// clustering is done.
return $clusters;
}
/**
* @param $nbClusters
* @param $seed
* @param $clustersNumber
* @param $initMethod
*
* @return array
* @return array|Cluster[]
*/
protected function initializeClusters($nbClusters, $seed)
protected function initializeClusters(int $clustersNumber, int $initMethod)
{
if ($nbClusters <= 0) {
throw new InvalidArgumentException('invalid clusters number');
}
switch ($seed) {
// the default seeding method chooses completely random centroid
switch ($initMethod) {
case KMeans::INIT_RANDOM:
// get the space boundaries to avoid placing clusters centroid too far from points
list($min, $max) = $this->getBoundaries();
// initialize N clusters with a random point within space boundaries
for ($n = 0; $n < $nbClusters; ++$n) {
for ($n = 0; $n < $clustersNumber; ++$n) {
$clusters[] = new Cluster($this, $this->getRandomPoint($min, $max)->getCoordinates());
}
break;
// the DASV seeding method consists of finding good initial centroids for the clusters
case KMeans::INIT_KMEANS_PLUS_PLUS:
// find a random point
$position = rand(1, count($this));
for ($i = 1, $this->rewind(); $i < $position && $this->valid(); $i++, $this->next());
$clusters[] = new Cluster($this, $this->current()->getCoordinates());
// retains the distances between points and their closest clusters
$distances = new SplObjectStorage();
// create k clusters
for ($i = 1; $i < $nbClusters; ++$i) {
for ($i = 1; $i < $clustersNumber; ++$i) {
$sum = 0;
// for each points, get the distance with the closest centroid already choosen
foreach ($this as $point) {
$distance = $point->getDistanceWith($point->getClosest($clusters));
$sum += $distances[$point] = $distance;
}
// choose a new random point using a weighted probability distribution
$sum = rand(0, (int) $sum);
foreach ($this as $point) {
if (($sum -= $distances[$point]) > 0) {
@ -213,8 +183,6 @@ class Space extends SplObjectStorage
break;
}
// assing all points to the first cluster
$clusters[0]->attachAll($this);
return $clusters;
@ -227,19 +195,15 @@ class Space extends SplObjectStorage
*/
protected function iterate($clusters)
{
$continue = false;
$convergence = true;
// migration storages
$attach = new SplObjectStorage();
$detach = new SplObjectStorage();
// calculate proximity amongst points and clusters
foreach ($clusters as $cluster) {
foreach ($cluster as $point) {
// find the closest cluster
$closest = $point->getClosest($clusters);
// move the point from its old cluster to its closest
if ($closest !== $cluster) {
isset($attach[$closest]) || $attach[$closest] = new SplObjectStorage();
isset($detach[$cluster]) || $detach[$cluster] = new SplObjectStorage();
@ -247,12 +211,11 @@ class Space extends SplObjectStorage
$attach[$closest]->attach($point);
$detach[$cluster]->attach($point);
$continue = true;
$convergence = false;
}
}
}
// perform points migrations
foreach ($attach as $cluster) {
$cluster->attachAll($attach[$cluster]);
}
@ -261,11 +224,10 @@ class Space extends SplObjectStorage
$cluster->detachAll($detach[$cluster]);
}
// update all cluster's centroids
foreach ($clusters as $cluster) {
$cluster->updateCentroid();
}
return $continue;
return $convergence;
}
}