diff --git a/maths/average_weighted.py b/maths/average_weighted.py new file mode 100644 index 000000000000..8738efb318ed --- /dev/null +++ b/maths/average_weighted.py @@ -0,0 +1,38 @@ +from __future__ import annotations + + +def weighted_mean(values: list[float], weights: list[float]) -> float: + """ + Return the weighted mean of a list of values given their weights. + Wiki: https://en.wikipedia.org/wiki/Weighted_arithmetic_mean + + >>> weighted_mean([10, 20, 30], [1, 2, 3]) + 23.333333333333332 + >>> weighted_mean([5, 5, 5], [1, 1, 1]) + 5.0 + >>> weighted_mean([], []) + Traceback (most recent call last): + ... + ValueError: values and weights cannot be empty + >>> weighted_mean([1, 2], [1]) + Traceback (most recent call last): + ... + ValueError: values and weights must have the same length + >>> weighted_mean([1, 2], [0, 0]) + Traceback (most recent call last): + ... + ValueError: sum of weights cannot be zero + """ + if len(values) == 0: + raise ValueError("values and weights cannot be empty") + if len(values) != len(weights): + raise ValueError("values and weights must have the same length") + if sum(weights) == 0: + raise ValueError("sum of weights cannot be zero") + return sum(x * w for x, w in zip(values, weights)) / sum(weights) + + +if __name__ == "__main__": + import doctest + + doctest.testmod() diff --git a/maths/weighted_average.py b/maths/weighted_average.py new file mode 100644 index 000000000000..a6a309c1cd63 --- /dev/null +++ b/maths/weighted_average.py @@ -0,0 +1,44 @@ +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()