from __future__ import annotations def weighted_average(values: list[float], weights: list[float]) -> float: """ Return the weighted average of a list of values given their corresponding weights. https://en.wikipedia.org/wiki/Weighted_arithmetic_mean >>> weighted_average([1, 2, 3], [1, 1, 1]) 2.0 >>> weighted_average([10, 20, 30], [1, 2, 3]) 23.333333333333332 >>> weighted_average([5, 15], [1, 3]) 12.5 >>> weighted_average([100], [0.5]) 100.0 >>> weighted_average([], []) Traceback (most recent call last): ... ValueError: Inputs cannot be empty >>> weighted_average([1, 2], [1]) Traceback (most recent call last): ... ValueError: Values and weights must have the same length >>> weighted_average([1, 2, 3], [0, 0, 0]) Traceback (most recent call last): ... ValueError: Sum of weights cannot be zero """ if not values: raise ValueError("Inputs cannot be empty") if len(values) != len(weights): raise ValueError("Values and weights must have the same length") total_weight = sum(weights) if total_weight == 0: raise ValueError("Sum of weights cannot be zero") return sum(value * weight for value, weight in zip(values, weights)) / total_weight if __name__ == "__main__": import doctest doctest.testmod()