[SPARK-9893] User guide with Java test suite for VectorSlicer

Add user guide for `VectorSlicer`, with Java test suite and Python version VectorSlicer.

Note that Python version does not support selecting by names now.

Author: Xusen Yin <yinxusen@gmail.com>

Closes #8267 from yinxusen/SPARK-9893.

(cherry picked from commit 630a994e6a9785d1704f8e7fb604f32f5dea24f8)
Signed-off-by: Xiangrui Meng <meng@databricks.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java
new file mode 100644
index 0000000000..56988b9fb2
--- /dev/null
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java
@@ -0,0 +1,85 @@
+/*
+ * 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 com.google.common.collect.Lists;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.ml.attribute.Attribute;
+import org.apache.spark.ml.attribute.AttributeGroup;
+import org.apache.spark.ml.attribute.NumericAttribute;
+import org.apache.spark.mllib.linalg.Vector;
+import org.apache.spark.mllib.linalg.Vectors;
+import org.apache.spark.sql.DataFrame;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.RowFactory;
+import org.apache.spark.sql.SQLContext;
+import org.apache.spark.sql.types.StructType;
+
+
+public class JavaVectorSlicerSuite {
+  private transient JavaSparkContext jsc;
+  private transient SQLContext jsql;
+
+  @Before
+  public void setUp() {
+    jsc = new JavaSparkContext("local", "JavaVectorSlicerSuite");
+    jsql = new SQLContext(jsc);
+  }
+
+  @After
+  public void tearDown() {
+    jsc.stop();
+    jsc = null;
+  }
+
+  @Test
+  public void vectorSlice() {
+    Attribute[] attrs = new Attribute[]{
+      NumericAttribute.defaultAttr().withName("f1"),
+      NumericAttribute.defaultAttr().withName("f2"),
+      NumericAttribute.defaultAttr().withName("f3")
+    };
+    AttributeGroup group = new AttributeGroup("userFeatures", attrs);
+
+    JavaRDD<Row> jrdd = jsc.parallelize(Lists.newArrayList(
+      RowFactory.create(Vectors.sparse(3, new int[]{0, 1}, new double[]{-2.0, 2.3})),
+      RowFactory.create(Vectors.dense(-2.0, 2.3, 0.0))
+    ));
+
+    DataFrame dataset = jsql.createDataFrame(jrdd, (new StructType()).add(group.toStructField()));
+
+    VectorSlicer vectorSlicer = new VectorSlicer()
+      .setInputCol("userFeatures").setOutputCol("features");
+
+    vectorSlicer.setIndices(new int[]{1}).setNames(new String[]{"f3"});
+
+    DataFrame output = vectorSlicer.transform(dataset);
+
+    for (Row r : output.select("userFeatures", "features").take(2)) {
+      Vector features = r.getAs(1);
+      Assert.assertEquals(features.size(), 2);
+    }
+  }
+}