平均パーセント計算機

1function finite(name, v) {2  if (typeof v !== "number" || !Number.isFinite(v)) throw new TypeError(`${name} must be a finite number`);3}4​5function places(decimals) {6  if (!Number.isInteger(decimals) || decimals < 0 || decimals > 10) throw new RangeError("decimals must be a whole number from 0 to 10");7  return decimals;8}9​10function list(name, values) {11  if (!Array.isArray(values) || values.length < 1) throw new TypeError(`${name} must be a non-empty array of numbers`);12  values.forEach((v) => finite(name, v));13}14​15// Simple average: [80, 90, 70, 85] -> 81.2516export function averagePercent(values, decimals = 2) {17  list("values", values);18  const d = places(decimals);19  return Number((values.reduce((a, b) => a + b, 0) / values.length).toFixed(d));20}21​22// Weighted average: weights can be sample sizes, marks or any non-negative numbers23export function weightedAveragePercent(values, weights, decimals = 2) {24  list("values", values);25  list("weights", weights);26  if (values.length !== weights.length) throw new RangeError("values and weights must be the same length");27  if (weights.some((w) => w < 0)) throw new RangeError("weights must not be negative");28  const d = places(decimals);29  const total = weights.reduce((a, b) => a + b, 0);30  if (total === 0) throw new RangeError("the weights must not all be 0");31  const sum = values.reduce((acc, v, i) => acc + v * weights[i], 0);32  return Number((sum / total).toFixed(d));33}34​35// Average percentage change per period over several periods (geometric mean)36export function averageGrowth(ratesPercent, decimals = 2) {37  list("rates", ratesPercent);38  const d = places(decimals);39  let product = 1;40  for (const r of ratesPercent) {41    if (r <= -100) throw new RangeError("a rate of -100% or less cannot be averaged this way");42    product *= 1 + r / 100;43  }44  return Number(((Math.pow(product, 1 / ratesPercent.length) - 1) * 100).toFixed(d));45}

1from decimal import Decimal, ROUND_HALF_UP2from math import isfinite3​4​5def _num(name, v):6    if isinstance(v, bool) or not isinstance(v, (int, float, Decimal)) or not isfinite(float(v)):7        raise ValueError(f"{name} must be a finite number")8    return Decimal(str(v))9​10​11def _round(x, decimals):12    if not isinstance(decimals, int) or isinstance(decimals, bool) or not 0 <= decimals <= 10:13        raise ValueError("decimals must be a whole number from 0 to 10")14    return x.quantize(Decimal(1).scaleb(-decimals), rounding=ROUND_HALF_UP)15​16​17def _list(name, values):18    if not isinstance(values, (list, tuple)) or len(values) < 1:19        raise ValueError(f"{name} must be a non-empty list of numbers")20    return [_num(name, v) for v in values]21​22​23def average_percent(values, decimals=2):24    nums = _list("values", values)25    return _round(sum(nums) / len(nums), decimals)26​27​28def weighted_average_percent(values, weights, decimals=2):29    nums = _list("values", values)30    w = _list("weights", weights)31    if len(nums) != len(w):32        raise ValueError("values and weights must be the same length")33    if any(x < 0 for x in w):34        raise ValueError("weights must not be negative")35    total = sum(w)36    if total == 0:37        raise ValueError("the weights must not all be 0")38    return _round(sum(n * x for n, x in zip(nums, w)) / total, decimals)39​40​41def average_growth(rates_percent, decimals=2):42    rates = _list("rates", rates_percent)43    product = Decimal(1)44    for r in rates:45        if r <= -100:46            raise ValueError("a rate of -100% or less cannot be averaged this way")47        product *= 1 + r / 10048    return _round((product ** (Decimal(1) / len(rates)) - 1) * 100, decimals)