[SPARK-14340][EXAMPLE][DOC] Update Examples and User Guide for ml.BisectingKMeans

## What changes were proposed in this pull request?

1, add BisectingKMeans to ml-clustering.md
2, add the missing Scala BisectingKMeansExample
3, create a new datafile `data/mllib/sample_kmeans_data.txt`

## How was this patch tested?

manual tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #11844 from zhengruifeng/doc_bkm.

data/mllib/sample_kmeans_data.txt

+0 1:0.0 2:0.0 3:0.0
+1 1:0.1 2:0.1 3:0.1
+2 1:0.2 2:0.2 3:0.2
+3 1:9.0 2:9.0 3:9.0
+4 1:9.1 2:9.1 3:9.1
+5 1:9.2 2:9.2 3:9.2

docs/ml-clustering.md

@@ -104,4 +104,39 @@ Refer to the [Java API docs](api/java/org/apache/spark/ml/clustering/LDA.html) f
 {% include_example java/org/apache/spark/examples/ml/JavaLDAExample.java %}
 </div>
 
-</div>
\ No newline at end of file
+</div>
+
+## Bisecting k-means
+
+
+Bisecting k-means is a kind of [hierarchical clustering](https://en.wikipedia.org/wiki/Hierarchical_clustering) using a
+divisive (or "top-down") approach: all observations start in one cluster, and splits are performed recursively as one
+moves down the hierarchy.
+
+Bisecting K-means can often be much faster than regular K-means, but it will generally produce a different clustering.
+
+`BisectingKMeans` is implemented as an `Estimator` and generates a `BisectingKMeansModel` as the base model.
+
+### Example
+
+<div class="codetabs">
+
+<div data-lang="scala" markdown="1">
+Refer to the [Scala API docs](api/scala/index.html#org.apache.spark.ml.clustering.BisectingKMeans) for more details.
+
+{% include_example scala/org/apache/spark/examples/ml/BisectingKMeansExample.scala %}
+</div>
+
+<div data-lang="java" markdown="1">
+Refer to the [Java API docs](api/java/org/apache/spark/ml/clustering/BisectingKMeans.html) for more details.
+
+{% include_example java/org/apache/spark/examples/ml/JavaBisectingKMeansExample.java %}
+</div>
+
+<div data-lang="python" markdown="1">
+Refer to the [Python API docs](api/python/pyspark.ml.html#pyspark.ml.clustering.BisectingKMeans) for more details.
+
+{% include_example python/ml/bisecting_k_means_example.py %}
+</div>
+
+</div>

examples/src/main/java/org/apache/spark/examples/ml/JavaBisectingKMeansExample.java

@@ -17,27 +17,22 @@
 
 package org.apache.spark.examples.ml;
 
-import java.util.Arrays;
-import java.util.List;
-
-import org.apache.spark.sql.RowFactory;
-import org.apache.spark.sql.SparkSession;
 // $example on$
 import org.apache.spark.ml.clustering.BisectingKMeans;
 import org.apache.spark.ml.clustering.BisectingKMeansModel;
 import org.apache.spark.mllib.linalg.Vector;
-import org.apache.spark.mllib.linalg.VectorUDT;
-import org.apache.spark.mllib.linalg.Vectors;
 import org.apache.spark.sql.Dataset;
 import org.apache.spark.sql.Row;
-import org.apache.spark.sql.types.Metadata;
-import org.apache.spark.sql.types.StructField;
-import org.apache.spark.sql.types.StructType;
 // $example off$
+import org.apache.spark.sql.SparkSession;
 
 
 /**
- * An example demonstrating a bisecting k-means clustering.
+ * An example demonstrating bisecting k-means clustering.
+ * Run with
+ * <pre>
+ * bin/run-example ml.JavaBisectingKMeansExample
+ * </pre>
  */
 public class JavaBisectingKMeansExample {
 
@@ -48,30 +43,22 @@ public class JavaBisectingKMeansExample {
       .getOrCreate();
 
     // $example on$
-    List<Row> data = Arrays.asList(
-      RowFactory.create(Vectors.dense(0.1, 0.1, 0.1)),
-      RowFactory.create(Vectors.dense(0.3, 0.3, 0.25)),
-      RowFactory.create(Vectors.dense(0.1, 0.1, -0.1)),
-      RowFactory.create(Vectors.dense(20.3, 20.1, 19.9)),
-      RowFactory.create(Vectors.dense(20.2, 20.1, 19.7)),
-      RowFactory.create(Vectors.dense(18.9, 20.0, 19.7))
-    );
-
-    StructType schema = new StructType(new StructField[]{
-      new StructField("features", new VectorUDT(), false, Metadata.empty()),
-    });
-
-    Dataset<Row> dataset = spark.createDataFrame(data, schema);
+    // Loads data.
+    Dataset<Row> dataset = spark.read().format("libsvm").load("data/mllib/sample_kmeans_data.txt");
 
-    BisectingKMeans bkm = new BisectingKMeans().setK(2);
+    // Trains a bisecting k-means model.
+    BisectingKMeans bkm = new BisectingKMeans().setK(2).setSeed(1);
     BisectingKMeansModel model = bkm.fit(dataset);
 
-    System.out.println("Compute Cost: " + model.computeCost(dataset));
+    // Evaluate clustering.
+    double cost = model.computeCost(dataset);
+    System.out.println("Within Set Sum of Squared Errors = " + cost);
 
-    Vector[] clusterCenters = model.clusterCenters();
-    for (int i = 0; i < clusterCenters.length; i++) {
-      Vector clusterCenter = clusterCenters[i];
-      System.out.println("Cluster Center " + i + ": " + clusterCenter);
+    // Shows the result.
+    System.out.println("Cluster Centers: ");
+    Vector[] centers = model.clusterCenters();
+    for (Vector center : centers) {
+      System.out.println(center);
     }
     // $example off$
 

examples/src/main/python/ml/bisecting_k_means_example.py

@@ -18,15 +18,14 @@
 from __future__ import print_function
 
 # $example on$
-from pyspark.ml.clustering import BisectingKMeans, BisectingKMeansModel
-from pyspark.mllib.linalg import VectorUDT, _convert_to_vector, Vectors
-from pyspark.mllib.linalg import Vectors
-from pyspark.sql.types import Row
+from pyspark.ml.clustering import BisectingKMeans
 # $example off$
 from pyspark.sql import SparkSession
 
 """
-A simple example demonstrating a bisecting k-means clustering.
+An example demonstrating bisecting k-means clustering.
+Run with:
+  bin/spark-submit examples/src/main/python/ml/bisecting_k_means_example.py
 """
 
 if __name__ == "__main__":
@@ -36,21 +35,20 @@ if __name__ == "__main__":
         .getOrCreate()
 
     # $example on$
-    data = spark.read.text("data/mllib/kmeans_data.txt").rdd
-    parsed = data\
-        .map(lambda row: Row(features=Vectors.dense([float(x) for x in row.value.split(' ')])))
-    training = spark.createDataFrame(parsed)
+    # Loads data.
+    dataset = spark.read.format("libsvm").load("data/mllib/sample_kmeans_data.txt")
 
-    kmeans = BisectingKMeans().setK(2).setSeed(1).setFeaturesCol("features")
+    # Trains a bisecting k-means model.
+    bkm = BisectingKMeans().setK(2).setSeed(1)
+    model = bkm.fit(dataset)
 
-    model = kmeans.fit(training)
+    # Evaluate clustering.
+    cost = model.computeCost(dataset)
+    print("Within Set Sum of Squared Errors = " + str(cost))
 
-    # Evaluate clustering
-    cost = model.computeCost(training)
-    print("Bisecting K-means Cost = " + str(cost))
-
-    centers = model.clusterCenters()
+    # Shows the result.
     print("Cluster Centers: ")
+    centers = model.clusterCenters()
     for center in centers:
         print(center)
     # $example off$

examples/src/main/scala/org/apache/spark/examples/ml/BisectingKMeansExample.scala

+/*
+ * 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.examples.ml
+
+// scalastyle:off println
+
+// $example on$
+import org.apache.spark.ml.clustering.BisectingKMeans
+// $example off$
+import org.apache.spark.sql.SparkSession
+
+/**
+ * An example demonstrating bisecting k-means clustering.
+ * Run with
+ * {{{
+ * bin/run-example ml.BisectingKMeansExample
+ * }}}
+ */
+object BisectingKMeansExample {
+
+  def main(args: Array[String]): Unit = {
+    // Creates a SparkSession
+    val spark = SparkSession
+      .builder
+      .appName("BisectingKMeansExample")
+      .getOrCreate()
+
+    // $example on$
+    // Loads data.
+    val dataset = spark.read.format("libsvm").load("data/mllib/sample_kmeans_data.txt")
+
+    // Trains a bisecting k-means model.
+    val bkm = new BisectingKMeans().setK(2).setSeed(1)
+    val model = bkm.fit(dataset)
+
+    // Evaluate clustering.
+    val cost = model.computeCost(dataset)
+    println(s"Within Set Sum of Squared Errors = $cost")
+
+    // Shows the result.
+    println("Cluster Centers: ")
+    val centers = model.clusterCenters
+    centers.foreach(println)
+    // $example off$
+
+    spark.stop()
+  }
+}
+// scalastyle:on println
+