[SPARK-19291][SPARKR][ML] spark.gaussianMixture supports output log-likelihood.

## What changes were proposed in this pull request?
```spark.gaussianMixture``` supports output total log-likelihood for the model like R ```mvnormalmixEM```.

## How was this patch tested?
R unit test.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16646 from yanboliang/spark-19291.

1 files changed, 7 insertions, 0 deletions

diff --git a/R/pkg/inst/tests/testthat/test_mllib_clustering.R b/R/pkg/inst/tests/testthat/test_mllib_clustering.R
index cfbdea5c04..9de8362cde 100644
--- a/R/pkg/inst/tests/testthat/test_mllib_clustering.R
+++ b/R/pkg/inst/tests/testthat/test_mllib_clustering.R
@@ -56,6 +56,10 @@ test_that("spark.gaussianMixture", {
   #            [,1]     [,2]
   #  [1,] 0.2961543 0.160783
   #  [2,] 0.1607830 1.008878
+  #
+  #' model$loglik
+  #
+  #  [1] -46.89499
   # nolint end
   data <- list(list(-0.6264538, 0.1836433), list(-0.8356286, 1.5952808),
                list(0.3295078, -0.8204684), list(0.4874291, 0.7383247),
@@ -72,9 +76,11 @@ test_that("spark.gaussianMixture", {
   rMu <- c(0.11731091, -0.06192351, 10.363673, 9.897081)
   rSigma <- c(0.62049934, 0.06880802, 0.06880802, 1.27431874,
               0.2961543, 0.160783, 0.1607830, 1.008878)
+  rLoglik <- -46.89499
   expect_equal(stats$lambda, rLambda, tolerance = 1e-3)
   expect_equal(unlist(stats$mu), rMu, tolerance = 1e-3)
   expect_equal(unlist(stats$sigma), rSigma, tolerance = 1e-3)
+  expect_equal(unlist(stats$loglik), rLoglik, tolerance = 1e-3)
   p <- collect(select(predict(model, df), "prediction"))
   expect_equal(p$prediction, c(0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1))
 
@@ -88,6 +94,7 @@ test_that("spark.gaussianMixture", {
   expect_equal(stats$lambda, stats2$lambda)
   expect_equal(unlist(stats$mu), unlist(stats2$mu))
   expect_equal(unlist(stats$sigma), unlist(stats2$sigma))
+  expect_equal(unlist(stats$loglik), unlist(stats2$loglik))
 
   unlink(modelPath)
 })