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Analysis.groupBy implementation.

This commit is contained in:
Benjy 2012-10-10 18:21:44 -07:00 committed by Mark Harrah
parent 1f88fe9d7c
commit 0e472a99f9
1 changed files with 8 additions and 3 deletions
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11
util/relation/Relation.scala
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@ -72,10 +72,13 @@ trait Relation[A,B]
def contains(a: A, b: B): Boolean
/** Returns a relation with only pairs (a,b) for which f(a,b) is true.*/
def filter(f: (A,B) => Boolean): Relation[A,B]
/** Partitions this relation into a map of relations according to some discriminator function. */
def groupBy[K](f: ((A,B)) => K): Map[K, Relation[A,B]]
/** Returns all pairs in this relation.*/
def all: Traversable[(A,B)]
def forwardMap: Map[A, Set[B]]
def reverseMap: Map[B, Set[A]]
}
@ -93,7 +96,7 @@ private final class MRelation[A,B](fwd: Map[A, Set[B]], rev: Map[B, Set[A]]) ext
def size = fwd.size
def all: Traversable[(A,B)] = fwd.iterator.flatMap { case (a, bs) => bs.iterator.map( b => (a,b) ) }.toTraversable
def +(pair: (A,B)) = this + (pair._1, Set(pair._2))
def +(from: A, to: B) = this + (from, to :: Nil)
def +(from: A, to: Traversable[B]) =
@ -116,6 +119,8 @@ private final class MRelation[A,B](fwd: Map[A, Set[B]], rev: Map[B, Set[A]]) ext
def filter(f: (A,B) => Boolean): Relation[A,B] = Relation.empty[A,B] ++ all.filter(f.tupled)
def groupBy[K](f: ((A,B)) => K): Map[K, Relation[A,B]] = all.groupBy(f) mapValues { Relation.empty[A,B] ++ _ }
def contains(a: A, b: B): Boolean = forward(a)(b)
override def toString = all.map { case (a,b) => a + " -> " + b }.mkString("Relation [", ", ", "]")