drop tmp col from OneVsRest output

Author: mengxr

mllib/src/main/scala/org/apache/spark/ml/classification/OneVsRest.scala

@@ -131,6 +131,7 @@ final class OneVsRestModel private[ml] (
     // output label and label metadata as prediction
     val labelUdf = callUDF(label, DoubleType, col(accColName))
     aggregatedDataset.withColumn($(predictionCol), labelUdf.as($(predictionCol), labelMetadata))
+      .drop(accColName)
   }
 }
 

mllib/src/test/scala/org/apache/spark/ml/classification/OneVsRestSuite.scala

@@ -17,7 +17,8 @@
 
 package org.apache.spark.ml.classification
 
-import org.apache.spark.SparkFunSuite
+import org.scalatest.FunSuite
+
 import org.apache.spark.ml.attribute.NominalAttribute
 import org.apache.spark.ml.util.MetadataUtils
 import org.apache.spark.mllib.classification.LogisticRegressionWithLBFGS
@@ -29,7 +30,7 @@ import org.apache.spark.mllib.util.TestingUtils._
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.DataFrame
 
-class OneVsRestSuite extends SparkFunSuite with MLlibTestSparkContext {
+class OneVsRestSuite extends FunSuite with MLlibTestSparkContext {
 
   @transient var dataset: DataFrame = _
   @transient var rdd: RDD[LabeledPoint] = _
@@ -93,6 +94,15 @@ class OneVsRestSuite extends SparkFunSuite with MLlibTestSparkContext {
     val datasetWithLabelMetadata = dataset.select(labelWithMetadata, features)
     ova.fit(datasetWithLabelMetadata)
   }
+
+  test("SPARK-8049: OneVsRest shouldn't output temp columns") {
+    val logReg = new LogisticRegression()
+      .setMaxIter(1)
+    val ovr = new OneVsRest()
+      .setClassifier(logReg)
+    val output = ovr.fit(dataset).transform(dataset)
+    assert(output.schema.fieldNames.toSet === Set("label", "features", "prediction"))
+  }
 }
 
 private class MockLogisticRegression(uid: String) extends LogisticRegression(uid) {