比をパーセントに変換する計算機

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​10// [2, 3] -> [40, 60]; [3, 5, 2] -> [30, 50, 20]11export function ratioToPercent(parts, decimals = 2) {12  if (!Array.isArray(parts) || parts.length < 2) throw new TypeError("parts must be an array of at least two numbers");13  parts.forEach((p) => {14    finite("part", p);15    if (p < 0) throw new RangeError("parts must not be negative");16  });17  const d = places(decimals);18  const total = parts.reduce((a, b) => a + b, 0);19  if (total === 0) throw new RangeError("the parts must not all be 0");20  return parts.map((p) => Number(((p / total) * 100).toFixed(d)));21}22​23function gcd(a, b) {24  return b === 0 ? a : gcd(b, a % b);25}26​27// 25 -> [1, 3] (part to rest, simplified). Accepts up to 2 decimal places.28export function percentToRatio(percent) {29  finite("percent", percent);30  if (percent <= 0 || percent >= 100) throw new RangeError("percent must be above 0 and below 100");31  const p = Math.round(percent * 100);32  if (Math.abs(percent * 100 - p) > 1e-9) throw new RangeError("percent must have at most 2 decimal places");33  const rest = 10000 - p;34  const g = gcd(p, rest);35  return [p / g, rest / g];36}

1from decimal import Decimal, ROUND_HALF_UP2from math import gcd, 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 ratio_to_percent(parts, decimals=2):18    if not isinstance(parts, (list, tuple)) or len(parts) < 2:19        raise ValueError("parts must be a list of at least two numbers")20    nums = [_num("part", p) for p in parts]21    if any(n < 0 for n in nums):22        raise ValueError("parts must not be negative")23    total = sum(nums)24    if total == 0:25        raise ValueError("the parts must not all be 0")26    return [_round(n / total * 100, decimals) for n in nums]27​28​29def percent_to_ratio(percent):30    p = _num("percent", percent)31    if not 0 < p < 100:32        raise ValueError("percent must be above 0 and below 100")33    scaled = p * 10034    if scaled != scaled.to_integral_value():35        raise ValueError("percent must have at most 2 decimal places")36    a = int(scaled)37    b = 10000 - a38    g = gcd(a, b)39    return a // g, b // g