Github user tgaloppo commented on a diff in the pull request:
https://github.com/apache/spark/pull/4459#discussion_r24355867
--- Diff:
mllib/src/test/scala/org/apache/spark/mllib/clustering/GaussianMixtureSuite.scala
---
@@ -80,4 +81,60 @@ class GaussianMixtureSuite extends FunSuite with
MLlibTestSparkContext {
assert(gmm.gaussians(0).sigma ~== Esigma(0) absTol 1E-3)
assert(gmm.gaussians(1).sigma ~== Esigma(1) absTol 1E-3)
}
+
+ test("single cluster with sparse data") {
+ val data = sc.parallelize(Array(
+ Vectors.sparse(3, Array(0, 2), Array(4.0, 2.0)),
+ Vectors.sparse(3, Array(0, 2), Array(2.0, 4.0)),
+ Vectors.sparse(3, Array(1), Array(6.0))
+ ))
+
+ val Ew = 1.0
+ val Emu = Vectors.dense(2.0, 2.0, 2.0)
+ val Esigma = Matrices.dense(3, 3,
+ Array(8.0 / 3.0, -4.0, 4.0 / 3.0, -4.0, 8.0, -4.0, 4.0 / 3.0, -4.0,
8.0 / 3.0)
+ )
+
+ val seeds = Array(42, 1994, 27, 11, 0)
+ seeds.foreach { seed =>
+ val gmm = new GaussianMixture().setK(1).setSeed(seed).run(data)
+ assert(gmm.weights(0) ~== Ew absTol 1E-5)
+ assert(gmm.gaussians(0).mu ~== Emu absTol 1E-5)
+ }
--- End diff --
Should check covariance matrix here. The Esigma given here does not look
right. If you need help computing it, let me know.
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