flagon-io/automation-lab

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Scratch repository for testing automations.

Add mean, median, and standard deviation functions to math.js #20

Mergedsyntaqx merged into mainrequested by syntaqx

Approved by g1t

21	21		return result;
22	22		}
23	23
24		−	module.exports = { add, multiply, power };
	24	+	/** Returns the average of numbers; throws a TypeError if the array is empty. */
	25	+	function mean(numbers) {
	26	+	if (numbers.length === 0) {
	27	+	throw new TypeError("numbers must not be empty");
	28	+	}
	29	+	return numbers.reduce((sum, n) => sum + n, 0) / numbers.length;
	30	+	}
	31	+
	32	+	/** Returns the middle value of numbers (the average of the two middle values when the length is even); throws a TypeError if the array is empty. */
	33	+	function median(numbers) {
	34	+	if (numbers.length === 0) {
	35	+	throw new TypeError("numbers must not be empty");
	36	+	}
	37	+	const sorted = [...numbers].sort((a, b) => a - b);
	38	+	const mid = Math.floor(sorted.length / 2);
	39	+	return sorted.length % 2 === 0 ? (sorted[mid - 1] + sorted[mid]) / 2 : sorted[mid];
	40	+	}
	41	+
	42	+	/** Returns the population standard deviation of numbers; throws a TypeError if the array is empty. */
	43	+	function standard_deviation(numbers) {
	44	+	const avg = mean(numbers);
	45	+	const variance = numbers.reduce((sum, n) => sum + (n - avg) ** 2, 0) / numbers.length;
	46	+	return Math.sqrt(variance);
	47	+	}
	48	+
	49	+	module.exports = { add, multiply, power, mean, median, standard_deviation };

6	6		assert.strictEqual(math.power(2, 10), 1024);
7	7		assert.strictEqual(math.power(5, 0), 1);
8	8		assert.throws(() => math.power(2, -1), RangeError);
	9	+	assert.strictEqual(math.mean([1, 2, 3, 4]), 2.5);
	10	+	assert.strictEqual(math.median([3, 1, 2]), 2);
	11	+	assert.strictEqual(math.median([4, 1, 3, 2]), 2.5);
	12	+	assert.strictEqual(math.standard_deviation([2, 4, 4, 4, 5, 5, 7, 9]), 2);
	13	+	for (const fn of [math.mean, math.median, math.standard_deviation]) {
	14	+	assert.throws(() => fn([]), TypeError);
	15	+	}
9	16		console.log("all tests passed");