[SPARK-16445][MLLIB][SPARKR] Multilayer Perceptron Classifier wrapper in SparkR

https://issues.apache.org/jira/browse/SPARK-16445

## What changes were proposed in this pull request?

Create Multilayer Perceptron Classifier wrapper in SparkR

## How was this patch tested?

Tested manually on local machine

Author: Xin Ren <iamshrek@126.com>

Closes #14447 from keypointt/SPARK-16445.

1 files changed, 32 insertions, 0 deletions

diff --git a/R/pkg/inst/tests/testthat/test_mllib.R b/R/pkg/inst/tests/testthat/test_mllib.R
index de9bd48662..1e6da650d1 100644
--- a/R/pkg/inst/tests/testthat/test_mllib.R
+++ b/R/pkg/inst/tests/testthat/test_mllib.R
@@ -347,6 +347,38 @@ test_that("spark.kmeans", {
   unlink(modelPath)
 })
 
+test_that("spark.mlp", {
+  df <- read.df("data/mllib/sample_multiclass_classification_data.txt", source = "libsvm")
+  model <- spark.mlp(df, blockSize = 128, layers = c(4, 5, 4, 3), solver = "l-bfgs", maxIter = 100,
+                     tol = 0.5, stepSize = 1, seed = 1)
+
+  # Test summary method
+  summary <- summary(model)
+  expect_equal(summary$labelCount, 3)
+  expect_equal(summary$layers, c(4, 5, 4, 3))
+  expect_equal(length(summary$weights), 64)
+
+  # Test predict method
+  mlpTestDF <- df
+  mlpPredictions <- collect(select(predict(model, mlpTestDF), "prediction"))
+  expect_equal(head(mlpPredictions$prediction, 6), c(0, 1, 1, 1, 1, 1))
+
+  # Test model save/load
+  modelPath <- tempfile(pattern = "spark-mlp", fileext = ".tmp")
+  write.ml(model, modelPath)
+  expect_error(write.ml(model, modelPath))
+  write.ml(model, modelPath, overwrite = TRUE)
+  model2 <- read.ml(modelPath)
+  summary2 <- summary(model2)
+
+  expect_equal(summary2$labelCount, 3)
+  expect_equal(summary2$layers, c(4, 5, 4, 3))
+  expect_equal(length(summary2$weights), 64)
+
+  unlink(modelPath)
+
+})
+
 test_that("spark.naiveBayes", {
   # R code to reproduce the result.
   # We do not support instance weights yet. So we ignore the frequencies.