Add timeFidelity to getTimelinePrediction()

Author: bkeepers

README.md

@@ -55,7 +55,8 @@ const timeline = getTimelinePrediction({
   lat: 26.7,
   lon: -80.05,
   start: new Date('2025-12-19T00:00:00-05:00'),
-  end: new Date('2025-12-19T01:00:00-05:00')
+  end: new Date('2025-12-19T01:00:00-05:00'),
+  timeFidelity: 5 * 60 // seconds, defaults to `10 * 60`
 })
 
 console.log(timeline)
@@ -67,13 +68,11 @@ console.log(timeline)
 //     // ...
 //   },
 //   timeline: [
-//     { time: 2025-12-19T05:00:00.000Z, hour: 0, level: 0.07269280868130157 },
-//     { time: 2025-12-19T05:10:00.000Z, hour: 0.16666666666666666, level: 0.054517202710722634 },
-//     { time: 2025-12-19T05:20:00.000Z, hour: 0.3333333333333333, level: 0.0387568479105333 },
-//     { time: 2025-12-19T05:30:00.000Z, hour: 0.5, level: 0.025594147655661648 },
-//     { time: 2025-12-19T05:40:00.000Z, hour: 0.6666666666666666, level: 0.015185512178782279 },
-//     { time: 2025-12-19T05:50:00.000Z, hour: 0.8333333333333334, level: 0.00765764296563648 },
-//     { time: 2025-12-19T06:00:00.000Z, hour: 1, level: 0.0031046829237997287 }
+//     { time: 2025-12-19T05:00:00.000Z, hour: 0, level: 0.7232836255650095 },
+//     { time: 2025-12-19T05:06:00.000Z, hour: 0.1, level: 0.7231644154595303 },
+//     { time: 2025-12-19T05:12:00.000Z, hour: 0.2, level: 0.7221097788490487 },
+//     { time: 2025-12-19T05:18:00.000Z, hour: 0.3, level: 0.7201242512580206 },
+//     // ...
 //   ]
 // }
 ```

packages/tide-predictor/src/index.ts

@@ -15,6 +15,7 @@ export interface TidePredictionOptions {
 export interface TimeSpan {
   start: Date
   end: Date
+  timeFidelity?: number
 }
 
 export interface ExtremesInput extends TimeSpan {
@@ -23,7 +24,6 @@ export interface ExtremesInput extends TimeSpan {
     low?: string
   }
   offsets?: ExtremeOffsets
-  timeFidelity?: number
 }
 
 export interface TidePrediction {
@@ -44,10 +44,14 @@ const tidePredictionFactory = (
   }
 
   const tidePrediction: TidePrediction = {
-    getTimelinePrediction: ({ start, end }: TimeSpan): TimelinePoint[] => {
+    getTimelinePrediction: ({
+      start,
+      end,
+      timeFidelity
+    }: TimeSpan): TimelinePoint[] => {
       return harmonics(harmonicsOptions)
         .setTimeSpan(start, end)
-        .prediction()
+        .prediction({ timeFidelity })
         .getTimelinePrediction()
     },
 

packages/tide-predictor/test/index.test.ts

@@ -44,6 +44,19 @@ describe('Tidal station', () => {
       start: startDate,
       end: endDate
     })
+    expect(results.length).toBe(37)
+    expect(results[0].level).toBeCloseTo(-1.34712509, 3)
+    const lastResult = results.pop()
+    expect(lastResult?.level).toBeCloseTo(2.85263589, 3)
+  })
+
+  it('it predicts the tides in a timeline with time fidelity', () => {
+    const results = tidePrediction(mockConstituents).getTimelinePrediction({
+      start: startDate,
+      end: endDate,
+      timeFidelity: 60
+    })
+    expect(results.length).toBe(361)
     expect(results[0].level).toBeCloseTo(-1.34712509, 3)
     const lastResult = results.pop()
     expect(lastResult?.level).toBeCloseTo(2.85263589, 3)