[SPARK-31301] flatten the result dataframe of tests in stat

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.0
• Fix Version/s: 3.1.0
• Component/s: ML
• Assignee: Ruifeng Zheng
• Reporter: Ruifeng Zheng
• Created: 30/Mar/20 09:23
• Updated: 20/Apr/20 04:30
• Resolved: 14/Apr/20 06:45

Description

 scala> import org.apache.spark.ml.linalg.{Vector, Vectors}
import org.apache.spark.ml.linalg.{Vector, Vectors}scala> import org.apache.spark.ml.stat.ChiSquareTest
import org.apache.spark.ml.stat.ChiSquareTestscala>     val data = Seq(
     |       (0.0, Vectors.dense(0.5, 10.0)),
     |       (0.0, Vectors.dense(1.5, 20.0)),
     |       (1.0, Vectors.dense(1.5, 30.0)),
     |       (0.0, Vectors.dense(3.5, 30.0)),
     |       (0.0, Vectors.dense(3.5, 40.0)),
     |       (1.0, Vectors.dense(3.5, 40.0))
     |     )
data: Seq[(Double, org.apache.spark.ml.linalg.Vector)] = List((0.0,[0.5,10.0]), (0.0,[1.5,20.0]), (1.0,[1.5,30.0]), (0.0,[3.5,30.0]), (0.0,[3.5,40.0]), (1.0,[3.5,40.0]))scala> scala> scala> val df = data.toDF("label", "features")
df: org.apache.spark.sql.DataFrame = [label: double, features: vector]scala>     val chi = ChiSquareTest.test(df, "features", "label")
chi: org.apache.spark.sql.DataFrame = [pValues: vector, degreesOfFreedom: array<int> ... 1 more field]scala> chi.show
+--------------------+----------------+----------+
|             pValues|degreesOfFreedom|statistics|
+--------------------+----------------+----------+
|[0.68728927879097...|          [2, 3]|[0.75,1.5]|
+--------------------+----------------+----------+

 

Current impls of ChiSquareTest, ANOVATest, FValueTest, Correlation all return a df only containing one row.

I think this is quite hard to use, suppose we have a dataset with dim=1000, the only operation we can deal with the test result is to collect it by head() or first(), and then use it in the driver.

While what I really want to do is filtering the df like pValue>0.1 or corr<0.5, So I suggest to flatten the output df in those tests.

 

note: {{ANOVATest}} and{{FValueTest}} are newly added in 3.1.0, but {{ChiSquareTest}} and {{Correlation}} were here for a long time.

 

 

 

 

Issue Links

• is related to: SPARK-31492 flatten the result dataframe of FValueTest
• is related to: SPARK-31494 flatten the result dataframe of ANOVATest
• links to: GitHub Pull Request #28176