From f432ecb5dafb29aae931256f2abf62f62cf56a90 Mon Sep 17 00:00:00 2001
From: Alexey Kopytko <alexey@kopytko.com>
Date: Wed, 9 Oct 2024 14:27:08 +0900
Subject: [PATCH] Make sensitivity accept floats for better precision (#12)

---
 src/AnomalyDetectionResult.php       | 10 +++++-----
 src/SlidingWindowCounter.php         |  4 ++--
 tests/AnomalyDetectionResultTest.php |  4 ++--
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/AnomalyDetectionResult.php b/src/AnomalyDetectionResult.php
index c64a8d8..ea3752b 100644
--- a/src/AnomalyDetectionResult.php
+++ b/src/AnomalyDetectionResult.php
@@ -54,8 +54,8 @@ class AnomalyDetectionResult
     /** @var float The mean value */
     private float $mean;
 
-    /** @var int The sensitivity */
-    private int $sensitivity;
+    /** @var float|int The sensitivity */
+    private float|int $sensitivity;
 
     /** @var float The low bound */
     private float $low;
@@ -78,9 +78,9 @@ class AnomalyDetectionResult
      * @param float $std_dev The standard deviation
      * @param float $mean The mean value
      * @param float $latest The latest value
-     * @param int $sensitivity The sensitivity (see `SlidingWindowCounter::detectAnomaly()`)
+     * @param float|int $sensitivity The sensitivity (see `SlidingWindowCounter::detectAnomaly()`)
      */
-    public function __construct(float $std_dev, float $mean, float $latest, int $sensitivity)
+    public function __construct(float $std_dev, float $mean, float $latest, float|int $sensitivity)
     {
         $this->std_dev = $std_dev;
         $this->mean = $mean;
@@ -145,7 +145,7 @@ public function getMean(): float
     /**
      * The sensitivity.
      */
-    public function getSensitivity(): int
+    public function getSensitivity(): float|int
     {
         return $this->sensitivity;
     }
diff --git a/src/SlidingWindowCounter.php b/src/SlidingWindowCounter.php
index 93165c2..b79744d 100644
--- a/src/SlidingWindowCounter.php
+++ b/src/SlidingWindowCounter.php
@@ -241,10 +241,10 @@ public function getLatestValue(string $bucket_key): float
      * Tests the standard deviation against the acceptable range and returns the alert message.
      *
      * @param string $bucket_key The bucket key
-     * @param int $sensitivity The sensitivity: 3 = low (99.7%), 2 = standard (95%) 1 = high (68% deviation triggers alert)
+     * @param float|int $sensitivity The sensitivity: 3 = low (99.7%), 2 = standard (95%) 1 = high (68% deviation triggers alert)
      * @param null|int $start_time The optional start time; leaving out the start time will omit the leading null values
      */
-    public function detectAnomaly(string $bucket_key, int $sensitivity = 2, ?int $start_time = null): AnomalyDetectionResult
+    public function detectAnomaly(string $bucket_key, float|int $sensitivity = 2, ?int $start_time = null): AnomalyDetectionResult
     {
         $variance = $this->getHistoricVariance($bucket_key, $start_time);
 
diff --git a/tests/AnomalyDetectionResultTest.php b/tests/AnomalyDetectionResultTest.php
index c9a3cef..54cc384 100644
--- a/tests/AnomalyDetectionResultTest.php
+++ b/tests/AnomalyDetectionResultTest.php
@@ -57,11 +57,11 @@ public function testHappyPath(): void
      */
     public function testAllGetters(): void
     {
-        $result = new AnomalyDetectionResult(1.0, 10.0, 11.0, 1);
+        $result = new AnomalyDetectionResult(1.0, 10.0, 11.0, 0.9);
 
         $this->assertSame(1.0, $result->getStandardDeviation());
         $this->assertSame(10.0, $result->getMean());
-        $this->assertSame(1, $result->getSensitivity());
+        $this->assertSame(0.9, $result->getSensitivity());
         $this->assertSame(9.0, $result->getLow());
         $this->assertSame(11.0, $result->getHigh());
         $this->assertSame(11.0, $result->getLatest());