Cuber

“Cubes” a case class or tuple, i.e. for a tuple of type (T1, T2, ... , TN) generates all 2^N possible combinations of type (Option[T1], Option[T2], ... , Option[TN]).

This is useful for comparing some metric across all possible subsets.

For example, suppose we have a set of people represented as

case class Person(gender: String, age: Int, height: Double)

and we want to know the average height of

• people, grouped by gender and age
• people, grouped by only gender
• people, grouped by only age
• all people

Then we could do

import com.twitter.algebird.macros.Cuber.cuber
val people: List[People]
val averageHeights: Map[(Option[String], Option[Int]), Double] =
  people.flatMap { p => cuber((p.gender, p.age)).map((_,p)) }
    .groupBy(_._1)
    .mapValues { xs => val heights = xs.map(_.height); heights.sum / heights.length }

Documentation Help

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• Cuber.scala