Fixed missing subtraction operation of intersection set length.

2 files changed, 16 insertions, 18 deletions

diff --git a/core/source/core/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala b/core/source/core/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala
index 3b9b418..6941b10 100755
--- a/core/source/core/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala
+++ b/core/source/core/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala
@@ -1,6 +1,6 @@
 package com.rockymadden.stringmetric.similarity
 
-import com.rockymadden.stringmetric.{StringMetric, MatchTuple, StringFilter}
+import com.rockymadden.stringmetric.{ StringMetric, MatchTuple, StringFilter }
 import com.rockymadden.stringmetric.tokenization.NGramTokenizer
 
 /* An implementation of the Jaccard metric. */
@@ -15,17 +15,15 @@ class JaccardMetric extends StringMetric[Int, Double] { this: StringFilter =>
 		else if (fca1.sameElements(fca2)) Some(1d)
 		else NGramTokenizer.tokenize(fca1)(n).flatMap { ca1bg =>
 			NGramTokenizer.tokenize(fca2)(n).map { ca2bg =>
-				val ms = scoreMatches(ca1bg.map(_.mkString), ca2bg.map(_.mkString))
+				val i = (ca1bg.map(_.mkString) intersect ca2bg.map(_.mkString)).length
 
-				ms.toDouble / (ca1bg.length + ca2bg.length)
+				i.toDouble / (ca1bg.length + ca2bg.length - i)
 			}
 		}
 	}
 
 	final override def compare(string1: String, string2: String)(implicit n: Int): Option[Double] =
 		compare(string1.toCharArray, string2.toCharArray)(n: Int)
-
-	private[this] def scoreMatches(mt: MatchTuple[String]) = mt._1.intersect(mt._2).length
 }
 
 object JaccardMetric {
diff --git a/core/source/test/scala/com/rockymadden/stringmetric/similarity/JaccardMetricSpec.scala b/core/source/test/scala/com/rockymadden/stringmetric/similarity/JaccardMetricSpec.scala
index a3aeb5e..17bc3ef 100755
--- a/core/source/test/scala/com/rockymadden/stringmetric/similarity/JaccardMetricSpec.scala
+++ b/core/source/test/scala/com/rockymadden/stringmetric/similarity/JaccardMetricSpec.scala
@@ -41,22 +41,22 @@ final class JaccardMetricSpec extends ScalaTest {
 			}
 			"valid arguments" should returns {
 				"Double indicating distance" in {
-					Metric.compare("night", "nacht")(1).get should be (0.3)
-					Metric.compare("night", "naght")(1).get should be (0.4)
-					Metric.compare("context", "contact")(1).get should be (0.35714285714285715)
+					Metric.compare("night", "nacht")(1).get should be (0.42857142857142855)
+					Metric.compare("night", "naght")(1).get should be (0.6666666666666666)
+					Metric.compare("context", "contact")(1).get should be (0.5555555555555556)
 
-					Metric.compare("night", "nacht")(2).get should be (0.125)
-					Metric.compare("night", "naght")(2).get should be (0.25)
-					Metric.compare("context", "contact")(2).get should be (0.25)
-					Metric.compare("contextcontext", "contact")(2).get should be (0.15789473684210525)
-					Metric.compare("context", "contactcontact")(2).get should be (0.15789473684210525)
-					Metric.compare("ht", "nacht")(2).get should be (0.2)
+					Metric.compare("night", "nacht")(2).get should be (0.14285714285714285)
+					Metric.compare("night", "naght")(2).get should be (0.3333333333333333)
+					Metric.compare("context", "contact")(2).get should be (0.3333333333333333)
+					Metric.compare("contextcontext", "contact")(2).get should be (0.1875)
+					Metric.compare("context", "contactcontact")(2).get should be (0.1875)
+					Metric.compare("ht", "nacht")(2).get should be (0.25)
 					Metric.compare("xp", "nacht")(2).get should be (0)
-					Metric.compare("ht", "hththt")(2).get should be (0.16666666666666666)
+					Metric.compare("ht", "hththt")(2).get should be (0.2)
 
 					Metric.compare("night", "nacht")(3).get should be (0)
-					Metric.compare("night", "naght")(3).get should be (0.16666666666666666)
-					Metric.compare("context", "contact")(3).get should be (0.2)
+					Metric.compare("night", "naght")(3).get should be (0.2)
+					Metric.compare("context", "contact")(3).get should be (0.25)
 				}
 			}
 		}
@@ -64,7 +64,7 @@ final class JaccardMetricSpec extends ScalaTest {
 	"JaccardMetric companion object" should provide {
 		"pass-through compare method" should returns {
 			"same value as class" in {
-				JaccardMetric.compare("context", "contact")(3).get should be (0.2)
+				JaccardMetric.compare("context", "contact")(3).get should be (0.25)
 			}
 		}
 	}