Improved quantile

arguiot · Sep 9, 2022 · 59ac707 · 59ac707
1 parent d00bca4
commit 59ac707
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Showing 3 changed files with 33 additions and 4 deletions.
diff --git a/Euler.xcodeproj/project.pbxproj b/Euler.xcodeproj/project.pbxproj
@@ -37,6 +37,7 @@
 		68C12AD12483284800BB4B3A /* Engineering.swift in Sources */ = {isa = PBXBuildFile; fileRef = 68C12AD02483284800BB4B3A /* Engineering.swift */; };
 		68C12AD32483392C00BB4B3A /* Substring.swift in Sources */ = {isa = PBXBuildFile; fileRef = 68C12AD22483392C00BB4B3A /* Substring.swift */; };
 		68C12AD524833E6500BB4B3A /* TablesTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 68C12AD424833E6500BB4B3A /* TablesTest.swift */; };
+		68F6882C28CA9BB9009806F2 /* StatisticsTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 68F6882B28CA9BB9009806F2 /* StatisticsTests.swift */; };
 		OBJ_176 /* Expression.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_10 /* Expression.swift */; };
 		OBJ_177 /* Grouper.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_12 /* Grouper.swift */; };
 		OBJ_178 /* LaTeX.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_13 /* LaTeX.swift */; };
@@ -153,6 +154,7 @@
 		68C12AD02483284800BB4B3A /* Engineering.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Engineering.swift; sourceTree = "<group>"; };
 		68C12AD22483392C00BB4B3A /* Substring.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Substring.swift; sourceTree = "<group>"; };
 		68C12AD424833E6500BB4B3A /* TablesTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TablesTest.swift; sourceTree = "<group>"; };
+		68F6882B28CA9BB9009806F2 /* StatisticsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatisticsTests.swift; sourceTree = "<group>"; };
 		"Euler::Euler::Product" /* Euler.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = Euler.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		"Euler::EulerTests::Product" /* EulerTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; path = EulerTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		OBJ_10 /* Expression.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Expression.swift; sourceTree = "<group>"; };
@@ -593,6 +595,7 @@
 				OBJ_106 /* NodeTests.swift */,
 				OBJ_107 /* Tools */,
 				68C12AD424833E6500BB4B3A /* TablesTest.swift */,
+				68F6882B28CA9BB9009806F2 /* StatisticsTests.swift */,
 			);
 			name = EulerTests;
 			path = Tests/EulerTests;
@@ -787,6 +790,7 @@
 				OBJ_270 /* ExtensionsTests.swift in Sources */,
 				OBJ_271 /* GeneratorsTests.swift in Sources */,
 				OBJ_272 /* GeometryTests.swift in Sources */,
+				68F6882C28CA9BB9009806F2 /* StatisticsTests.swift in Sources */,
 				OBJ_273 /* MatrixTest.swift in Sources */,
 				OBJ_274 /* NodeTests.swift in Sources */,
 				OBJ_275 /* Convenience.swift in Sources */,

diff --git a/Sources/Euler/Statistics/Quantile.swift b/Sources/Euler/Statistics/Quantile.swift
@@ -33,9 +33,9 @@ public extension Statistics {
         let half = Int(floor(Double(sorted.count) / 2.0))
 
         if self.list.count % 2 == 0 {
-            return sorted[half]
-        } else {
             return (sorted[half - 1] + sorted[half]) / 2
+        } else {
+            return sorted[half]
         }
     }
 
@@ -49,8 +49,8 @@ public extension Statistics {
         var array = self.list
         let n = array.removeFirst()
         let sorted = array.sorted()
-        let index = (sorted.count - 1) * n
-        guard let floored = floor(index).asInt() else { throw QuantileError.ArrayLength }
+        let index = Double(sorted.count - 1) * percentage
+        let floored = Int(index)
         let diff = index - BigDouble(floored)
 
         if index + 1 >= BigDouble(sorted.count) {

diff --git a/Tests/EulerTests/StatisticsTests.swift b/Tests/EulerTests/StatisticsTests.swift
@@ -0,0 +1,25 @@
+//
+//  StatisticsTests.swift
+//  EulerTests
+//
+//  Created by Arthur Guiot on 08/09/2022.
+//
+
+import XCTest
+import Euler
+class StatisticsTests: XCTestCase {
+    func testQuantile() {
+        let array: [BN] = [32.2, 32.0, 30.4, 31.0, 31.2, 31.2, 30.3, 29.6, 30.5, 30.7]
+
+        let stats = Statistics(list: array)
+
+        XCTAssertEqual(stats.median, BN(617, over: 20))
+        XCTAssertEqual(try stats.quantile(percentage: 0.5), 30.7)
+        XCTAssertEqual(try stats.quantile(percentage: 0.25), 30.4)
+        XCTAssertEqual(try stats.quantile(percentage: 0.75), 31.2)
+    }
+
+    static var allTests = [
+        ("Quantile", testQuantile),
+    ]
+}