Average and normalized intensities

src/average-intensity.ts

@@ -0,0 +1,19 @@
+import { chain, pipe, sum } from "ramda";
+import { Interval } from "./ast";
+
+// Converts interval to array of intensity values for each second
+const intervalToIntensities = ({ duration, intensity }: Interval): number[] => {
+  const seconds = [];
+  const { from, to } = intensity;
+  for (let i = 0; i < duration; i++) {
+    // Intensity in a single second
+    seconds.push(from + (to - from) * (i / duration));
+  }
+  return seconds;
+};
+
+const average = (arr: number[]) => sum(arr) / arr.length;
+
+export const averageIntensity = (intervals: Interval[]): number => {
+  return pipe(chain(intervalToIntensities), average)(intervals);
+};

src/index.ts

@@ -1,4 +1,6 @@
 import * as fs from "fs";
+import { averageIntensity } from "./average-intensity";
+import { normalizedIntensity } from "./normalized-intensity";
 import { parse } from "./parser";
 import { tokenize } from "./tokenizer";
 import { tss } from "./tss";
@@ -23,3 +25,7 @@ const duration =
   workout.intervals.map(({ duration }) => duration).reduce((a, b) => a + b, 0) /
   60;
 console.log(`Total duration: ${duration} minutes`);
+
+console.log();
+console.log(`Average intensity: ${averageIntensity(workout.intervals)}`);
+console.log(`Normalized intensity: ${normalizedIntensity(workout.intervals)}`);

src/normalized-intensity.ts

@@ -0,0 +1,46 @@
+import { chain, pipe, sum } from "ramda";
+import { Interval } from "./ast";
+
+// Converts interval to array of intensity values for each second
+const intervalToIntensities = ({ duration, intensity }: Interval): number[] => {
+  const seconds = [];
+  const { from, to } = intensity;
+  for (let i = 0; i < duration; i++) {
+    // Intensity in a single second
+    seconds.push(from + (to - from) * (i / duration));
+  }
+  return seconds;
+};
+
+// Starting at the beginning of the data, calculate 30-second rolling average
+const windowSize = 30;
+const rollingAverages = (intensities: number[]): number[] => {
+  if (intensities.length < windowSize) {
+    throw new Error(`Workout must be at least ${windowSize} seconds long`);
+  }
+  const averages: number[] = [];
+  let rollingSum: number = sum(intensities.slice(0, windowSize));
+  averages.push(rollingSum / windowSize);
+  for (let i = 0; i < intensities.length - windowSize; i++) {
+    rollingSum -= intensities[i];
+    rollingSum += intensities[i + windowSize];
+    averages.push(rollingSum / windowSize);
+  }
+  return averages;
+};
+
+const fourthPower = (x: number) => Math.pow(x, 4);
+
+const fourthRoot = (x: number) => Math.pow(x, 1 / 4);
+
+const average = (arr: number[]) => sum(arr) / arr.length;
+
+export const normalizedIntensity = (intervals: Interval[]): number => {
+  return pipe(
+    chain(intervalToIntensities),
+    rollingAverages,
+    (averages) => averages.map(fourthPower),
+    average,
+    fourthRoot
+  )(intervals);
+};