为什么我会收到 ValueError？

Question

我有两个看起来完全相同的文件： 文件1

1 in seattle today the secretary of education richard riley delivered his address 
1 one of the things he focused on as the president had done
1 abc's michele norris has been investigating this
2 we're going to take a closer look tonight at the difficulty of getting meaningful

文件2

1 in seattl today the secretari of educ richard riley deliv hi address
1 one of the thing he focus on a the presid had done
1 abc michel norri ha been investig thi 
2 we'r go to take a closer look tonight at the difficulti of get meaning

当我运行这段代码时：

result=defaultdict(list)
with open("onthis.txt","r") as filer:
    for line in filer:
        label, sentence= line.strip().split(' ', 1)
        result[label].append(sentence)

它适用于 file1，但给我一个 file2 的值错误：

label, sentence= line.strip().split(' ', 1)
ValueError: need more than 1 value to unpack

当它们都采用相同的格式时，我似乎不明白原因。 所以，我只是通过这个终端命令删除了空行：

sed '/^$/d' onthis.txt > trial

但是出现了同样的错误。

Answer 1

它们不可能完全相同。我的猜测是您的第二个文件中某处有一个空行/仅空白行，很可能就在末尾。

错误告诉您，当它执行拆分时，没有要拆分的空格，因此只返回一个值，而不是 label 和 sentence 的值。

Answer 2

根据您的编辑，我怀疑您的文本文件中可能仍有“空”行。好吧，我可能应该说：行中只有空白。

我已经扩展了您的示例文件：

1 in seattl today the secretari of educ richard riley deliv hi address
1 one of the thing he focus on a the presid had done
1 abc michel norri ha been investig thi 
2 we'r go to take a closer look tonight at the difficulti of get meaning
 3   foo

4 bar


5 qun

可能不清楚，但3 foo 和4 bar 之间的行被几个空格填充，而4 bar 5 qun 之间的行“只是”新行（\n）。

注意sed '/^$/d'的输出

1 in seattl today the secretari of educ richard riley deliv hi address
1 one of the thing he focus on a the presid had done
1 abc michel norri ha been investig thi 
2 we'r go to take a closer look tonight at the difficulti of get meaning
 3   foo

4 bar
5 qun

真正删除了空行 - 毫无疑问。但是伪空的空白行仍然存在。运行你的 python 脚本会在到达这一行时抛出一个错误：

2 we'r go to take a closer look tonight at the difficulti of get meaning

 3   foo    

Traceback (most recent call last):
  File "python.py", line 9, in <module>
    label, sentence= line.strip().split(' ', 1)
ValueError: need more than 1 value to unpack

所以我的建议是将您的脚本扩展一行，使其跳过输入文件中的空行。

for line in filer:
    if not line.strip(): continue

这样做有积极的副作用，您不必在之前使用一些sed-magic 准备输入文件。

Answer 3

基于您提供的上述内容（经过调整）。这似乎给出了预期的结果。

result = {}

with open("test.txt", "r") as filer:
    for line in filer:
        label, sentence = line.strip().split(' ', 1)
        try:
            result[label].append(sentence)
        except KeyError:
            result[label] = [sentence]

输出：

{'2': ["we'r go to take a closer look tonight at the difficulti of get meaning"], '1': ['in seattl today the secretari of educ richard riley deliv hi address', 'one of the thing he focus on a the presid had done', 'abc michel norri ha been investig thi']}

所以这一定意味着我们在您提供的内容中缺少某些内容。我认为，如果以上内容不能满足您的需求，则需要更多信息