Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/13656#discussion_r66928786
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/fpm/AssociationRules.scala ---
@@ -120,6 +120,13 @@ object AssociationRules {
@Since("1.5.0")
def confidence: Double = freqUnion.toDouble / freqAntecedent
+ /**
+ * Returns the support of the rule. Current implementation would
return the number of
+ * co-occurrence of antecedent and consequent.
+ */
+ @Since("2.1.0")
+ def support: Double = freqUnion.toDouble
+
--- End diff --
Dunno, that seems like a mistake to me. It should be a `Long` if it's a
count, and should expose alternative factory methods to accept input of
different types if needed. Overloading one argument seems like a hack and I'd
prefer not to extend it (or fix it).
See SPARK-15930 which concerns adding the input size just for this reason,
I assume. We haven't released 2.0, and so could in theory still put in a change
to the constructor. I agree, we might however have to deprecate the existing
one, add a new one, and still deal with calls to the old constructor, which
would mean it's not possible to compute values that are a fraction of the whole
data set. This in turn may argue for clearly separating inputs/outputs that are
counts vs percentages.
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