add test suite

mllib/src/main/scala/org/apache/spark/ml/feature/Bucketizer.scala

@@ -19,7 +19,7 @@ package org.apache.spark.ml.feature
 
 import org.apache.spark.annotation.AlphaComponent
 import org.apache.spark.ml.Transformer
-import org.apache.spark.ml.attribute.{NominalAttribute, BinaryAttribute}
+import org.apache.spark.ml.attribute.NominalAttribute
 import org.apache.spark.ml.param._
 import org.apache.spark.ml.param.shared.{HasInputCol, HasOutputCol}
 import org.apache.spark.ml.util.SchemaUtils
@@ -29,18 +29,17 @@ import org.apache.spark.sql.types.{DoubleType, StructType}
 
 /**
  * :: AlphaComponent ::
- * Binarize a column of continuous features given a threshold.
+ * `Bucketizer` maps a column of continuous features to a column of feature buckets.
  */
 @AlphaComponent
 final class Bucketizer extends Transformer with HasInputCol with HasOutputCol {
 
   /**
-   * Param for threshold used to binarize continuous features.
-   * The features greater than the threshold, will be binarized to 1.0.
-   * The features equal to or less than the threshold, will be binarized to 0.0.
+   * Parameter for mapping continuous features into buckets.
    * @group param
    */
-  val buckets: Param[Array[Double]] = new Param[Array[Double]](this, "buckets", "")
+  val buckets: Param[Array[Double]] = new Param[Array[Double]](this, "buckets",
+    "Map continuous features into buckets.")
 
   /** @group getParam */
   def getBuckets: Array[Double] = $(buckets)
@@ -64,7 +63,7 @@ final class Bucketizer extends Transformer with HasInputCol with HasOutputCol {
   }
 
   /**
-   * Binary searching in several bins to place each data point.
+   * Binary searching in several buckets to place each data point.
    */
   private def binarySearchForBins(splits: Array[Double], feature: Double): Double = {
     val wrappedSplits = Array(Double.MinValue) ++ splits ++ Array(Double.MaxValue)

mllib/src/test/scala/org/apache/spark/ml/feature/BucketizerSuite.scala

@@ -0,0 +1,44 @@
+/*
+ * 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.feature
+
+import org.apache.spark.mllib.util.MLlibTestSparkContext
+import org.apache.spark.sql.{DataFrame, Row, SQLContext}
+import org.scalatest.FunSuite
+
+class BucketizerSuite extends FunSuite with MLlibTestSparkContext {
+
+  test("Bucket continuous features with setter") {
+    val sqlContext = new SQLContext(sc)
+    val data = Array(0.1, -0.5, 0.2, -0.3, 0.8, 0.7, -0.1, -0.4)
+    val buckets = Array(-0.5, 0.0, 0.5)
+    val bucketizedData = Array(2.0, 0.0, 2.0, 1.0, 3.0, 3.0, 1.0, 1.0)
+    val dataFrame: DataFrame = sqlContext.createDataFrame(
+        data.zip(bucketizedData)).toDF("feature", "expected")
+
+    val bucketizer: Bucketizer = new Bucketizer()
+      .setInputCol("feature")
+      .setOutputCol("result")
+      .setBuckets(buckets)
+
+    bucketizer.transform(dataFrame).select("result", "expected").collect().foreach {
+      case Row(x: Double, y: Double) =>
+        assert(x === y, "The feature value is not correct after bucketing.")
+    }
+  }
+}