[SPARK-5885][MLLIB] Add VectorAssembler as a feature transformer

VectorAssembler merges multiple columns into a vector column. This PR contains content from #5195.

~~carry ML attributes~~ (moved to a follow-up PR)

Author: Xiangrui Meng <meng@databricks.com>

Closes #5196 from mengxr/SPARK-5885 and squashes the following commits:

a52b101 [Xiangrui Meng] recognize more types
35daac2 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-5885
bb5e64b [Xiangrui Meng] add TODO for null
976a3d6 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-5885
0859311 [Xiangrui Meng] Revert "add CreateStruct"
29fb6ac [Xiangrui Meng] use CreateStruct
adb71c4 [Xiangrui Meng] Merge branch 'SPARK-6542' into SPARK-5885
85f3106 [Xiangrui Meng] add CreateStruct
4ff16ce [Xiangrui Meng] add VectorAssembler

1 files changed, 63 insertions, 0 deletions

diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/VectorAssemblerSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/VectorAssemblerSuite.scala
new file mode 100644
index 0000000000..57d0278e03
--- /dev/null
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/VectorAssemblerSuite.scala
@@ -0,0 +1,63 @@
+/*
+ * 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.scalatest.FunSuite
+
+import org.apache.spark.SparkException
+import org.apache.spark.mllib.linalg.{Vector, Vectors}
+import org.apache.spark.mllib.util.MLlibTestSparkContext
+import org.apache.spark.sql.{Row, SQLContext}
+
+class VectorAssemblerSuite extends FunSuite with MLlibTestSparkContext {
+
+  @transient var sqlContext: SQLContext = _
+
+  override def beforeAll(): Unit = {
+    super.beforeAll()
+    sqlContext = new SQLContext(sc)
+  }
+
+  test("assemble") {
+    import org.apache.spark.ml.feature.VectorAssembler.assemble
+    assert(assemble(0.0) === Vectors.sparse(1, Array.empty, Array.empty))
+    assert(assemble(0.0, 1.0) === Vectors.sparse(2, Array(1), Array(1.0)))
+    val dv = Vectors.dense(2.0, 0.0)
+    assert(assemble(0.0, dv, 1.0) === Vectors.sparse(4, Array(1, 3), Array(2.0, 1.0)))
+    val sv = Vectors.sparse(2, Array(0, 1), Array(3.0, 4.0))
+    assert(assemble(0.0, dv, 1.0, sv) ===
+      Vectors.sparse(6, Array(1, 3, 4, 5), Array(2.0, 1.0, 3.0, 4.0)))
+    for (v <- Seq(1, "a", null)) {
+      intercept[SparkException](assemble(v))
+      intercept[SparkException](assemble(1.0, v))
+    }
+  }
+
+  test("VectorAssembler") {
+    val df = sqlContext.createDataFrame(Seq(
+      (0, 0.0, Vectors.dense(1.0, 2.0), "a", Vectors.sparse(2, Array(1), Array(3.0)), 10L)
+    )).toDF("id", "x", "y", "name", "z", "n")
+    val assembler = new VectorAssembler()
+      .setInputCols(Array("x", "y", "z", "n"))
+      .setOutputCol("features")
+    assembler.transform(df).select("features").collect().foreach {
+      case Row(v: Vector) =>
+        assert(v === Vectors.sparse(6, Array(1, 2, 4, 5), Array(1.0, 2.0, 3.0, 10.0)))
+    }
+  }
+}