rollingAve1.js

import R from 'ramda';

const sma = (num, data, arr = []) => {
  if (R.length(data) === 0) {
    console.log(`arr: [${arr}] data: [${data}]`);
    return arr;
  } else if (R.length(data) < num) {
    console.log(`arr: [${arr}] data: [${data}]`);
    return sma(num, R.tail(data), R.prepend('not yet!', arr));
  }
  const newData = R.tail(data);
  const movingMean = R.mean(
    R.slice(0, num, data)
  );
  console.log(`arr: [${arr}] data: [${data}]`);
  return sma(num, newData, R.append(movingMean, arr));
};

console.log(sma(3, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]));
// arr= [] data= [1,2,3,4,5,6,7,8,9,10]
// arr= [2] data= [2,3,4,5,6,7,8,9,10]
// arr= [2,3] data= [3,4,5,6,7,8,9,10]
// arr= [2,3,4] data= [4,5,6,7,8,9,10]
// arr= [2,3,4,5] data= [5,6,7,8,9,10]
// arr= [2,3,4,5,6] data= [6,7,8,9,10]
// arr= [2,3,4,5,6,7] data= [7,8,9,10]
// arr= [2,3,4,5,6,7,8] data= [8,9,10]
// arr= [2,3,4,5,6,7,8,9] data= [9,10]
// arr= [not yet!,2,3,4,5,6,7,8,9] data= [10]
// arr= [not yet!,not yet!,2,3,4,5,6,7,8,9] data= []
// [ 'not yet!', 'not yet!', 2, 3, 4, 5, 6, 7, 8, 9 ]