Use center(segmentAfter) / center(segmentBefore) since ration doesn't work fine if the array contains 0

Author: MaXal

dashboard/new-dashboard/src/shared/changeDetector/algorithm.ts

@@ -1,4 +1,4 @@
-import { avgSpread, center, ratio, shift } from "pragmastat"
+import { avgSpread, center, shift } from "pragmastat"
 
 export enum ChangePointClassification {
   DEGRADATION = "Degradation",
@@ -53,11 +53,11 @@ export const classifyChangePoint = (changePointIndexes: number[], dataset: numbe
     const segmentBefore = dataset.slice(startBefore, endBefore)
     const segmentAfter = dataset.slice(startAfter, endAfter)
 
-    const ratioValue = ratio(segmentAfter, segmentBefore)
-    const percentageDifference = Math.abs((ratioValue - 1) * 100)
-
     const centerBefore = center(segmentBefore)
     const centerAfter = center(segmentAfter)
+    const ratioValue = centerAfter / centerBefore
+
+    const percentageDifference = Math.abs((ratioValue - 1) * 100)
     const absoluteChange = Math.abs(centerAfter - centerBefore)
 
     const shiftValue = shift(segmentAfter, segmentBefore)

pkg/degradation-detector/degradationDetector.go

@@ -68,12 +68,6 @@ func detectDegradations(values []int, builds []string, timestamps []int64, analy
 			continue
 		}
 
-		ratio, err := pragmastat.Ratio(lastSegment, segments[i])
-		if err != nil {
-			skippedSegments++
-			continue
-		}
-
 		currentCenter, err := pragmastat.Center(lastSegment)
 		if err != nil {
 			skippedSegments++
@@ -85,6 +79,8 @@ func detectDegradations(values []int, builds []string, timestamps []int64, analy
 			continue
 		}
 
+		ratio := currentCenter / previousCenter
+
 		percentageChange := math.Abs((ratio - 1) * 100)
 		absoluteChange := math.Abs(currentCenter - previousCenter)
 
@@ -97,7 +93,7 @@ func detectDegradations(values []int, builds []string, timestamps []int64, analy
 			break
 		}
 
-		isDegradation := ratio > 1
+		isDegradation := currentCenter > previousCenter
 		reportType := analysisSettings.GetReportType()
 
 		if !isDegradation && reportType == DegradationEvent {