From 38477208d3f8b8103a2a756f372da9968a397c43 Mon Sep 17 00:00:00 2001
From: Alexander Ignatov <yalishanda@abv.bg>
Date: Fri, 17 Dec 2021 00:58:10 +0200
Subject: [PATCH] Add fuzzify and fromCrispSet

---
 Sources/FuzzyKit/DiscreteFuzzySet.swift       | 14 +++++++++++++
 .../FuzzyKitTests/DiscreteFuzzySetTests.swift | 20 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/Sources/FuzzyKit/DiscreteFuzzySet.swift b/Sources/FuzzyKit/DiscreteFuzzySet.swift
index c0a3338..3b78d59 100644
--- a/Sources/FuzzyKit/DiscreteFuzzySet.swift
+++ b/Sources/FuzzyKit/DiscreteFuzzySet.swift
@@ -25,3 +25,17 @@ public struct DiscreteFuzzySet<Universe: Hashable>: FuzzySet {
         }
     }
 }
+
+public extension DiscreteFuzzySet {
+    static func fromCrispSet(_ set: Set<Universe>) -> Self {
+        let gradeTuples = set.map { ($0, 1.0 ) }
+        let gradeDictionary = Dictionary(uniqueKeysWithValues: gradeTuples)
+        return .init(elementToGradeMap: gradeDictionary)
+    }
+}
+
+public extension Set {
+    func fuzzified() -> DiscreteFuzzySet<Set.Element> {
+        DiscreteFuzzySet.fromCrispSet(self)
+    }
+}
diff --git a/Tests/FuzzyKitTests/DiscreteFuzzySetTests.swift b/Tests/FuzzyKitTests/DiscreteFuzzySetTests.swift
index 69c6a08..524ea81 100644
--- a/Tests/FuzzyKitTests/DiscreteFuzzySetTests.swift
+++ b/Tests/FuzzyKitTests/DiscreteFuzzySetTests.swift
@@ -60,4 +60,24 @@ final class DiscreteFuzzySetTests: XCTestCase {
             assertExpectedGrade(element: element, expectedGrade: grade, sut: sut2)
         }
     }
+    
+    func test_fuzzify_gradesAreCorrect() throws {
+        let cs: Set<String> = ["a", "b", "c"]
+        let expected = [
+            "a": 1.0,
+            "b": 1.0,
+            "c": 1.0,
+            "d": 0.0,
+            " ": 0.0,
+            "": 0.0,
+        ]
+        
+        let fs1 = cs.fuzzified()
+        let fs2 = DiscreteFuzzySet.fromCrispSet(cs)
+        
+        for (element, grade) in expected {
+            assertExpectedGrade(element: element, expectedGrade: grade, sut: fs1)
+            assertExpectedGrade(element: element, expectedGrade: grade, sut: fs2)
+        }
+    }
 }