Add overlap coefficient

src/gleam_community/maths/metrics.gleam

@@ -49,6 +49,7 @@ import gleam/list
 import gleam/pair
 import gleam/set
 import gleam/float
+import gleam/int
 
 /// <div style="text-align: right;">
 ///     <a href="https://github.com/gleam-community/maths/issues">
@@ -676,3 +677,37 @@ pub fn tversky_index(
     }
   }
 }
+
+/// <div style="text-align: right;">
+///     <a href="https://github.com/gleam-community/maths/issues">
+///         <small>Spot a typo? Open an issue!</small>
+///     </a>
+/// </div>
+/// 
+/// 
+/// <details>
+///     <summary>Example:</summary>
+///
+///     import gleeunit/should
+///     import gleam_community/maths/metrics
+///
+///     pub fn example () {
+///     }
+/// </details>
+///
+/// <div style="text-align: right;">
+///     <a href="#">
+///         <small>Back to top ↑</small>
+///     </a>
+/// </div>
+///
+pub fn overlap_coefficient(aset: set.Set(a), bset: set.Set(a)) -> Float {
+  let intersection: Float =
+    set.intersection(aset, bset)
+    |> set.size()
+    |> conversion.int_to_float()
+  let minsize: Float =
+    piecewise.minimum(set.size(aset), set.size(bset), int.compare)
+    |> conversion.int_to_float()
+  intersection /. minsize
+}

test/gleam_community/maths/metrics_test.gleam

@@ -234,3 +234,25 @@ pub fn example_jaccard_index_test() {
   metrics.jaccard_index(set_e, set_f)
   |> should.equal(1.0 /. 7.0)
 }
+
+pub fn example_overlap_coefficient_test() {
+  metrics.overlap_coefficient(set.from_list([]), set.from_list([]))
+  |> should.equal(0.0)
+
+  let set_a: set.Set(Int) = set.from_list([0, 1, 2, 5, 6, 8, 9])
+  let set_b: set.Set(Int) = set.from_list([0, 2, 3, 4, 5, 7, 9])
+  metrics.overlap_coefficient(set_a, set_b)
+  |> should.equal(4.0 /. 7.0)
+
+  let set_c: set.Set(Int) = set.from_list([0, 1, 2, 3, 4, 5])
+  let set_d: set.Set(Int) = set.from_list([6, 7, 8, 9, 10])
+  metrics.overlap_coefficient(set_c, set_d)
+  |> should.equal(0.0 /. 5.0)
+
+  let set_e: set.Set(String) =
+    set.from_list(["cat", "dog", "hippo", "monkey", "rhino"])
+  let set_f: set.Set(String) =
+    set.from_list(["monkey", "rhino", "ostrich", "salmon"])
+  metrics.overlap_coefficient(set_e, set_f)
+  |> should.equal(2.0 /. 4.0)
+}