python - 有多个值需要解压

Question

我运行这段代码:

def score(string, dic):
    for string in dic:
        word,score,std = string.lower().split()
        dic[word]=float(score),float(std)
        v = sum(dic[word] for word in string)
        return float(v)/len(string)

并得到这个错误:

word,score,std = string.split()
ValueError: need more than 1 value to unpack

Answer 1

这是因为 string.lower().split() 返回的列表只有一个项目。你不能将它分配给 word,score,std 除非这个列表恰好有 3 个成员；即 string 恰好包含 2 个空格。

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a, b, c = "a b c".split()  # works, 3-item list
a, b, c = "a b".split()  # doesn't work, 2-item list
a, b, c = "a b c d".split()  # doesn't work, 4-item list