Added java example for VectorSizeHint.

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

@@ -0,0 +1,79 @@
+/*
+ * 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;
+
+import org.apache.spark.ml.feature.VectorAssembler;
+import org.apache.spark.ml.feature.VectorSizeHint;
+import org.apache.spark.ml.linalg.VectorUDT;
+import org.apache.spark.ml.linalg.Vectors;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.RowFactory;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.types.StructField;
+import org.apache.spark.sql.types.StructType;
+
+import java.util.Arrays;
+
+import static org.apache.spark.sql.types.DataTypes.*;
+
+// $example on$
+// $example off$
+
+public class JavaVectorSizeHintExample {
+  public static void main(String[] args) {
+    SparkSession spark = SparkSession
+      .builder()
+      .appName("JavaVectorSizeHintExample")
+      .getOrCreate();
+
+    // $example on$
+    StructType schema = createStructType(new StructField[]{
+      createStructField("id", IntegerType, false),
+      createStructField("hour", IntegerType, false),
+      createStructField("mobile", DoubleType, false),
+      createStructField("userFeatures", new VectorUDT(), false),
+      createStructField("clicked", DoubleType, false)
+    });
+    Row row = RowFactory.create(0, 18, 1.0, Vectors.dense(0.0, 10.0, 0.5), 1.0);
+    Dataset<Row> dataset = spark.createDataFrame(Arrays.asList(row), schema);
+
+    VectorSizeHint sizeHint = new VectorSizeHint()
+      .setInputCol("userFeatures")
+      .setHandleInvalid("skip")
+      .setSize(3);
+
+    Dataset<Row> datasetWithSize = sizeHint.transform(dataset);
+    System.out.println("Rows where 'userFeatures' is not the right size are filtered out");
+    datasetWithSize.show(false);
+
+    VectorAssembler assembler = new VectorAssembler()
+      .setInputCols(new String[]{"hour", "mobile", "userFeatures"})
+      .setOutputCol("features");
+
+    // This dataframe can be used by used by downstream transformers as before
+    Dataset<Row> output = assembler.transform(datasetWithSize);
+    System.out.println("Assembled columns 'hour', 'mobile', 'userFeatures' to vector column " +
+        "'features'");
+    output.select("features", "clicked").show(false);
+    // $example off$
+
+    spark.stop();
+  }
+}
+