Details
Minor Description
When transform(...) method is called on a LinearRegressionModel created directly with the coefficients and intercepts, the following exception is encountered.
java.util.NoSuchElementException: Failed to find a default value for loss at org.apache.spark.ml.param.Params$$anonfun$getOrDefault$2.apply(params.scala:780) at org.apache.spark.ml.param.Params$$anonfun$getOrDefault$2.apply(params.scala:780) at scala.Option.getOrElse(Option.scala:121) at org.apache.spark.ml.param.Params$class.getOrDefault(params.scala:779) at org.apache.spark.ml.PipelineStage.getOrDefault(Pipeline.scala:42) at org.apache.spark.ml.param.Params$class.$(params.scala:786) at org.apache.spark.ml.PipelineStage.$(Pipeline.scala:42) at org.apache.spark.ml.regression.LinearRegressionParams$class.validateAndTransformSchema(LinearRegression.scala:111) at org.apache.spark.ml.regression.LinearRegressionModel.validateAndTransformSchema(LinearRegression.scala:637) at org.apache.spark.ml.PredictionModel.transformSchema(Predictor.scala:192) at org.apache.spark.ml.PipelineModel$$anonfun$transformSchema$5.apply(Pipeline.scala:311) at org.apache.spark.ml.PipelineModel$$anonfun$transformSchema$5.apply(Pipeline.scala:311) at scala.collection.IndexedSeqOptimized$class.foldl(IndexedSeqOptimized.scala:57) at scala.collection.IndexedSeqOptimized$class.foldLeft(IndexedSeqOptimized.scala:66) at scala.collection.mutable.ArrayOps$ofRef.foldLeft(ArrayOps.scala:186) at org.apache.spark.ml.PipelineModel.transformSchema(Pipeline.scala:311) at org.apache.spark.ml.PipelineStage.transformSchema(Pipeline.scala:74) at org.apache.spark.ml.PipelineModel.transform(Pipeline.scala:305)
This is because validateAndTransformSchema() is called both during training and scoring phases, but the checks against the training related params like loss should really be performed during training phase only, I think, please correct me if I'm missing anything.
This issue was first reported for mleap (combust/mleap#455) because basically when we serialize the Spark transformers for mleap, we only serialize the params that are relevant for scoring. We do have the option to de-serialize the serialized transformers back into Spark for scoring again, but in that case, we no longer have all the training params.
Test to reproduce in PR: https://github.com/apache/spark/pull/24509
