Github user jkbradley commented on a diff in the pull request:
https://github.com/apache/spark/pull/3099#discussion_r20116069
--- Diff: mllib/src/main/scala/org/apache/spark/ml/Pipeline.scala ---
@@ -0,0 +1,136 @@
+/*
+ * 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
+
+import scala.collection.mutable.ListBuffer
+
+import org.apache.spark.Logging
+import org.apache.spark.ml.param.{Param, ParamMap}
+import org.apache.spark.sql.{SchemaRDD, StructType}
+
+/**
+ * A stage in a pipeline, either an Estimator or an Transformer.
+ */
+abstract class PipelineStage extends Serializable with Logging {
+
+ /**
+ * Derives the output schema from the input schema and parameters.
+ */
+ def transform(schema: StructType, paramMap: ParamMap): StructType
+
+ /**
+ * Drives the output schema from the input schema and parameters,
optionally with logging.
+ */
+ protected def transform(schema: StructType, paramMap: ParamMap, logging:
Boolean): StructType = {
+ if (logging) {
+ logDebug(s"Input schema: ${schema.json}")
+ }
+ val outputSchema = transform(schema, paramMap)
+ if (logging) {
+ logDebug(s"Expected output schema: ${outputSchema.json}")
+ }
+ outputSchema
+ }
+}
+
+/**
+ * A simple pipeline, which acts as an estimator.
+ */
+class Pipeline extends Estimator[PipelineModel] {
+
+ val stages: Param[Array[PipelineStage]] = new Param(this, "stages",
"stages of the pipeline")
+ def setStages(value: Array[PipelineStage]): this.type = { set(stages,
value); this }
+ def getStages: Array[PipelineStage] = get(stages)
+
+ override def fit(dataset: SchemaRDD, paramMap: ParamMap): PipelineModel
= {
+ transform(dataset.schema, paramMap, logging = true)
+ val map = this.paramMap ++ paramMap
+ val theStages = map(stages)
+ // Search for the last estimator.
+ var lastIndexOfEstimator = -1
+ theStages.view.zipWithIndex.foreach { case (stage, index) =>
+ stage match {
+ case _: Estimator[_] =>
+ lastIndexOfEstimator = index
+ case _ =>
+ }
+ }
+ var curDataset = dataset
+ val transformers = ListBuffer.empty[Transformer]
+ theStages.view.zipWithIndex.foreach { case (stage, index) =>
+ stage match {
+ case estimator: Estimator[_] =>
+ val transformer = estimator.fit(curDataset, paramMap)
+ if (index < lastIndexOfEstimator) {
+ curDataset = transformer.transform(curDataset, paramMap)
--- End diff --
use map, not paramMap (here and elsewhere in Pipeline)
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