Python 计算字典中字符串的平均分数

我如何编写一个python程序，以任何字符串和字典的形式输入字典中的字符串值：

score("a b" , {"a":(1.2) , "b":(3.4)})

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并以浮点形式返回值的平均值？

在我看来，您希望：

def score(key_str,dct):
    keys = key_str.split()
    v = sum(dct[key] for key in keys)
    return float(v)/len(keys)

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这里有一个不那么抽象的答案

def score(hairypeople, hair_length):
    """ Calculates the average nosehair length given a string of people's names 
    and a dictionary of the length of their nose hairs.  """ 
    list_of_hairy_people = hairypeople.split()
    number_of_hairy_people = len(list_of_hairy_people)
    sum_length_of_hairs = sum([hair_length[ew] for ew in list_of_hairy_people])
    return float(sum_length_of_hairs) / number_of_hairy_people

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该字符串是如何解释的？示例中该字符串的值是多少？你试过什么？你到底想计算这里的平均值是多少？@gnibler——我明白了。删除了我的评论。