Xusen Yin created SPARK-13641:
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Summary: getModelFeatures of ml.api.r.SparkRWrapper cannot
(always) reveal the original column names
Key: SPARK-13641
URL: https://issues.apache.org/jira/browse/SPARK-13641
Project: Spark
Issue Type: Bug
Components: ML, SparkR
Reporter: Xusen Yin
Priority: Minor
getModelFeatures of ml.api.r.SparkRWrapper cannot (always) reveal the original
column names. Let's take the HouseVotes84 data set as an example:
{code}
case m: XXXModel =>
val attrs = AttributeGroup.fromStructField(
m.summary.predictions.schema(m.summary.featuresCol))
attrs.attributes.get.map(_.name.get)
{code}
The code above gets features' names from the features column. Usually, the
features column is generated by RFormula. The latter has a VectorAssembler in
it, which leads the output attributes not equal with the original ones.
E.g., we want to learn the HouseVotes84's features' name "V1, V2, ..., V16".
But with RFormula, we can only get "V1_n, V2_y, ..., V16_y" because [the
transform function of
VectorAssembler|https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/ml/feature/VectorAssembler.scala#L75]
adds salts of the column names.
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