[SPARK-17315][SPARKR] Kolmogorov-Smirnov test SparkR wrapper

## What changes were proposed in this pull request?

This PR tries to add Kolmogorov-Smirnov Test wrapper to SparkR. This wrapper implementation only supports one sample test against normal distribution.

## How was this patch tested?

R unit test.

Author: Junyang Qian <junyangq@databricks.com>

Closes #14881 from junyangq/SPARK-17315.

1 files changed, 57 insertions, 0 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/ml/r/KSTestWrapper.scala b/mllib/src/main/scala/org/apache/spark/ml/r/KSTestWrapper.scala
new file mode 100644
index 0000000000..21531eb057
--- /dev/null
+++ b/mllib/src/main/scala/org/apache/spark/ml/r/KSTestWrapper.scala
@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.ml.r
+
+import org.apache.spark.mllib.stat.Statistics.kolmogorovSmirnovTest
+import org.apache.spark.mllib.stat.test.KolmogorovSmirnovTestResult
+import org.apache.spark.sql.{DataFrame, Row}
+
+private[r] class KSTestWrapper private (
+    val testResult: KolmogorovSmirnovTestResult,
+    val distName: String,
+    val distParams: Array[Double]) {
+
+  lazy val pValue = testResult.pValue
+
+  lazy val statistic = testResult.statistic
+
+  lazy val nullHypothesis = testResult.nullHypothesis
+
+  lazy val degreesOfFreedom = testResult.degreesOfFreedom
+
+  def summary: String = testResult.toString
+}
+
+private[r] object KSTestWrapper {
+
+  def test(
+      data: DataFrame,
+      featureName: String,
+      distName: String,
+      distParams: Array[Double]): KSTestWrapper = {
+
+    val rddData = data.select(featureName).rdd.map {
+      case Row(feature: Double) => feature
+    }
+
+    val ksTestResult = kolmogorovSmirnovTest(rddData, distName, distParams : _*)
+
+    new KSTestWrapper(ksTestResult, distName, distParams)
+  }
+}
+