Github user WeichenXu123 commented on a diff in the pull request:
https://github.com/apache/spark/pull/16158#discussion_r137545402
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/tuning/ValidatorParams.scala ---
@@ -85,6 +86,32 @@ private[ml] trait ValidatorParams extends HasSeed with
Params {
instrumentation.logNamedValue("evaluator",
$(evaluator).getClass.getCanonicalName)
instrumentation.logNamedValue("estimatorParamMapsLength",
$(estimatorParamMaps).length)
}
+
+
+ /**
+ * Summary of grid search tuning in the format of DataFrame. Each row
contains one candidate
+ * paramMap and the corresponding metric of trained model.
+ */
+ protected def getTuningSummaryDF(metrics: Array[Double]): DataFrame = {
+ val params = $(estimatorParamMaps)
+ require(params.nonEmpty, "estimator param maps should not be empty")
+ require(params.length == metrics.length, "estimator param maps number
should match metrics")
+ val metricName = $(evaluator) match {
+ case b: BinaryClassificationEvaluator => b.getMetricName
+ case m: MulticlassClassificationEvaluator => m.getMetricName
+ case r: RegressionEvaluator => r.getMetricName
+ case _ => "metrics"
+ }
+ val spark = SparkSession.builder().getOrCreate()
+ val sc = spark.sparkContext
+ val fields = params(0).toSeq.sortBy(_.param.name).map(_.param.name) ++
Seq(metricName)
+ val schema = new StructType(fields.map(name => StructField(name,
StringType)).toArray)
+ val rows = sc.parallelize(params.zip(metrics)).map { case (param,
metric) =>
+ val values = param.toSeq.sortBy(_.param.name).map(_.value.toString)
++ Seq(metric.toString)
--- End diff --
Here seems exists a problem:
Suppose `params(0)` (which is a `ParamMap`) contains ParamA and ParamB,
and `params(1)` (which is a `ParamMap`) contains ParamA and ParamC,
The code here will run into problems. Because you compose the row values
sorted by param name but do not check whether every row exactly match the first
row.
I think better way is, go though the whole `ParamMap` list and collect all
params used, and sort them by name, as the dataframe schema.
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