1 files changed, 20 insertions, 0 deletions
diff --git a/core/src/main/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala b/core/src/main/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala
new file mode 100755
index 0000000..6ec5db4
--- /dev/null
+++ b/core/src/main/scala/com/rockymadden/stringmetric/similarity/JaccardMetric.scala
@@ -0,0 +1,20 @@
+package com.rockymadden.stringmetric.similarity
+
+import com.rockymadden.stringmetric.Metric.StringMetric
+
+final case class JaccardMetric(n: Int) extends StringMetric[Double] {
+	import com.rockymadden.stringmetric.Tokenize.NGramTokenizer
+
+	override def compare(a: Array[Char], b: Array[Char]): Option[Double] =
+		if (n <= 0 || a.length < n || b.length < n) None // Because length is less than n, it is not possible to compare.
+		else if (a.sameElements(b)) Some(1d)
+		else NGramTokenizer(n).tokenize(a).flatMap { ca1bg =>
+			NGramTokenizer(n).tokenize(b).map { ca2bg =>
+				val i = (ca1bg.map(_.mkString) intersect ca2bg.map(_.mkString)).length
+
+				i.toDouble / (ca1bg.length + ca2bg.length - i)
+			}
+		}
+
+	override def compare(a: String, b: String): Option[Double] = compare(a.toCharArray, b.toCharArray)
+}