Github user sethah commented on a diff in the pull request:
https://github.com/apache/spark/pull/15413#discussion_r85179044
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/clustering/GaussianMixture.scala ---
@@ -316,24 +319,129 @@ class GaussianMixture @Since("2.0.0") (
@Since("2.0.0")
def setSeed(value: Long): this.type = set(seed, value)
+ // number of samples per cluster to use when initializing Gaussians
+ private val nSamples = 5
+
@Since("2.0.0")
override def fit(dataset: Dataset[_]): GaussianMixtureModel = {
transformSchema(dataset.schema, logging = true)
- val rdd: RDD[OldVector] = dataset.select(col($(featuresCol))).rdd.map {
- case Row(point: Vector) => OldVectors.fromML(point)
+
+ val sc = dataset.sparkSession.sparkContext
+ val _k = $(k)
+
+ val instances: RDD[Vector] =
dataset.select(col($(featuresCol))).rdd.map {
+ case Row(features: Vector) => features
+ }.cache()
+
+ // Extract the number of features.
+ val numFeatures = instances.first().size
+
+ val shouldDistributeGaussians =
GaussianMixture.shouldDistributeGaussians(_k, numFeatures)
+
+ // Determine initial weights and corresponding Gaussians.
+ // We start with uniform weights, a random mean from the data, and
+ // diagonal covariance matrices using component variances
+ // derived from the samples.
+ // TODO: Support users supplied initial GMM.
+ val samples = instances.takeSample(withReplacement = true, _k *
nSamples, $(seed))
+ val weights: Array[Double] = Array.fill(_k)(1.0 / _k)
+ /**
--- End diff --
AFAIK we typically use `/* ... */` comments for longer comments inside
method bodies like this
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