Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/4925#discussion_r25988627
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/attribute/AttributeGroup.scala ---
@@ -0,0 +1,234 @@
+/*
+ * 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.attribute
+
+import scala.collection.mutable.ArrayBuffer
+
+import org.apache.spark.mllib.linalg.VectorUDT
+import org.apache.spark.sql.types.{Metadata, MetadataBuilder, StructField}
+
+/**
+ * Attributes that describe a vector ML column.
+ *
+ * @param name name of the attribute group (the ML column name)
+ * @param numAttributes optional number of attributes. At most one of
`numAttributes` and `attrs`
+ * can be defined.
+ * @param attrs optional array of attributes. Attribute will be copied
with their corresponding
+ * indices in the array.
+ */
+class AttributeGroup private (
--- End diff --
Does that effectively 'flatten' the schema, you mean? so if I have two
numeric columns, and one vector-valued columns with 3 features inside, then the
assembler makes a representation of 5 features? If that's right, then yes now I
get what you mean by this. So, there is nothing here that represents the
original schema with its nesting, since that would never be how it is presented
to an algorithm, right?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
