Bump default half window to 4

Author: matthewp

app/components/Package/WeeklyDownloadStats.vue

@@ -3,8 +3,8 @@ import { VueUiSparkline } from 'vue-data-ui/vue-ui-sparkline'
 import { useCssVariables } from '~/composables/useColors'
 import type { WeeklyDataPoint } from '~/types/chart'
 import { applyDataCorrection } from '~/utils/chart-data-correction'
-import { OKLCH_NEUTRAL_FALLBACK, lightenOklch } from '~/utils/colors'
 import { applyHampelCorrection } from '~/utils/download-anomalies'
+import { OKLCH_NEUTRAL_FALLBACK, lightenOklch } from '~/utils/colors'
 import type { RepoRef } from '#shared/utils/git-providers'
 import type { VueUiSparklineConfig, VueUiSparklineDatasetItem } from 'vue-data-ui'
 import { onKeyDown } from '@vueuse/core'

app/composables/useSettings.ts

@@ -71,7 +71,7 @@ const DEFAULT_SETTINGS: AppSettings = {
     averageWindow: 0,
     smoothingTau: 1,
     anomaliesFixed: true,
-    hampelWindow: 3,
+    hampelWindow: 4,
     hampelThreshold: 3,
     predictionPoints: 4,
   },

app/utils/download-anomalies.ts

@@ -11,7 +11,7 @@ import type { EvolutionData } from '~/types/chart'
  * package equally, with no manual curation.
  */
 
-const DEFAULT_HALF_WINDOW = 3
+const DEFAULT_HALF_WINDOW = 4
 const DEFAULT_THRESHOLD = 3
 
 function median(values: number[]): number {

test/unit/app/utils/download-anomalies.spec.ts

@@ -16,10 +16,12 @@ function makeWeeklyPoint(weekStart: string, value: number): WeeklyDataPoint {
 describe('applyHampelCorrection', () => {
   it('flags and corrects a spike in the middle of steady data', () => {
     const data: WeeklyDataPoint[] = [
+      makeWeeklyPoint('2022-10-24', 100),
+      makeWeeklyPoint('2022-10-31', 100),
       makeWeeklyPoint('2022-11-07', 100),
       makeWeeklyPoint('2022-11-14', 100),
-      makeWeeklyPoint('2022-11-21', 100),
-      makeWeeklyPoint('2022-11-28', 1000), // spike
+      makeWeeklyPoint('2022-11-21', 1000), // spike (index 4)
+      makeWeeklyPoint('2022-11-28', 100),
       makeWeeklyPoint('2022-12-05', 100),
       makeWeeklyPoint('2022-12-12', 100),
       makeWeeklyPoint('2022-12-19', 100),
@@ -28,18 +30,20 @@ describe('applyHampelCorrection', () => {
     const result = applyHampelCorrection(data) as WeeklyDataPoint[]
 
     // The spike should be corrected
-    expect(result[3]!.hasAnomaly).toBe(true)
-    expect(result[3]!.value).toBe(100) // replaced with median
+    expect(result[4]!.hasAnomaly).toBe(true)
+    expect(result[4]!.value).toBe(100) // replaced with median
 
     // Non-spike points should be unchanged
     expect(result[0]!.value).toBe(100)
     expect(result[0]!.hasAnomaly).toBeUndefined()
-    expect(result[1]!.value).toBe(100)
-    expect(result[6]!.value).toBe(100)
+    expect(result[3]!.value).toBe(100)
+    expect(result[8]!.value).toBe(100)
   })
 
   it('does not flag gradual growth as anomalies', () => {
     const data: WeeklyDataPoint[] = [
+      makeWeeklyPoint('2022-10-24', 80),
+      makeWeeklyPoint('2022-10-31', 90),
       makeWeeklyPoint('2022-11-07', 100),
       makeWeeklyPoint('2022-11-14', 110),
       makeWeeklyPoint('2022-11-21', 120),
@@ -70,6 +74,8 @@ describe('applyHampelCorrection', () => {
   it('does not flatten a "great start" (sudden real growth at the end)', () => {
     // A package going from zero to real adoption — this is NOT a spike.
     const data: WeeklyDataPoint[] = [
+      makeWeeklyPoint('2022-10-24', 0),
+      makeWeeklyPoint('2022-10-31', 0),
       makeWeeklyPoint('2022-11-07', 0),
       makeWeeklyPoint('2022-11-14', 0),
       makeWeeklyPoint('2022-11-21', 0),
@@ -82,41 +88,45 @@ describe('applyHampelCorrection', () => {
     const result = applyHampelCorrection(data) as WeeklyDataPoint[]
 
     // The 20000 should NOT be erased — it's real growth, not an anomaly.
-    expect(result[6]!.value).toBe(20000)
-    expect(result[6]!.hasAnomaly).toBeUndefined()
+    expect(result[8]!.value).toBe(20000)
+    expect(result[8]!.hasAnomaly).toBeUndefined()
   })
 
   it('does not flatten low-volume real activity', () => {
     // Sparse package with occasional real downloads
     const data: WeeklyDataPoint[] = [
+      makeWeeklyPoint('2022-10-24', 0),
+      makeWeeklyPoint('2022-10-31', 0),
       makeWeeklyPoint('2022-11-07', 0),
       makeWeeklyPoint('2022-11-14', 0),
-      makeWeeklyPoint('2022-11-21', 0),
-      makeWeeklyPoint('2022-11-28', 1),
+      makeWeeklyPoint('2022-11-21', 1),
       makeWeeklyPoint('2022-12-05', 0),
       makeWeeklyPoint('2022-12-12', 0),
       makeWeeklyPoint('2022-12-19', 0),
+      makeWeeklyPoint('2022-12-26', 0),
     ]
 
     const result = applyHampelCorrection(data) as WeeklyDataPoint[]
 
     // A single download is not an anomaly
-    expect(result[3]!.value).toBe(1)
-    expect(result[3]!.hasAnomaly).toBeUndefined()
+    expect(result[4]!.value).toBe(1)
+    expect(result[4]!.hasAnomaly).toBeUndefined()
   })
 
   it('does not mutate the original data', () => {
     const data: WeeklyDataPoint[] = [
+      makeWeeklyPoint('2022-10-24', 100),
+      makeWeeklyPoint('2022-10-31', 100),
       makeWeeklyPoint('2022-11-07', 100),
       makeWeeklyPoint('2022-11-14', 100),
-      makeWeeklyPoint('2022-11-21', 100),
-      makeWeeklyPoint('2022-11-28', 1000),
+      makeWeeklyPoint('2022-11-21', 1000),
+      makeWeeklyPoint('2022-11-28', 100),
       makeWeeklyPoint('2022-12-05', 100),
       makeWeeklyPoint('2022-12-12', 100),
       makeWeeklyPoint('2022-12-19', 100),
     ]
 
     applyHampelCorrection(data)
-    expect(data[3]!.value).toBe(1000) // original unchanged
+    expect(data[4]!.value).toBe(1000) // original unchanged
   })
 })