@thi.ng/transducers/moving-average.js

Collection of ~170 lightweight, composable transducers, reducers, generators, iterators for functional data transformations

import { isIterable } from "@thi.ng/checks/is-iterable";
import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
import { compR } from "./compr.js";
import { iterator1 } from "./iterator.js";
function movingAverage(period, src) {
  return isIterable(src) ? iterator1(movingAverage(period), src) : (rfn) => {
    period |= 0;
    period < 2 && illegalArgs("period must be >= 2");
    const reduce = rfn[2];
    const window = [];
    let sum = 0;
    return compR(rfn, (acc, x) => {
      const n = window.push(x);
      sum += x;
      n > period && (sum -= window.shift());
      return n >= period ? reduce(acc, sum / period) : acc;
    });
  };
}
export {
  movingAverage
};