使用另一个数组中的键快速、有效地对一个数组中选择的值进行平均

def average_with_keys(arr1, arr2):
    selected_values = [arr1[i] for i in arr2]  # 选择的值存储到新数组中
    counter = {}  # 字典用于存储计数器

    for key in arr2:
        if key in counter:
            counter[key] += 1
        else:
            counter[key] = 1

    for value in selected_values:
        if value in counter:
            counter[value] += 1
        else:
            counter[value] = 1

    result = {}
    for key, count in counter.items():
        result[key] = key / count

    return result