NLTK - UnigramTagger: TypeError: unhashable type: 'list'

Question

我从 NLTK 开始，并按照 NLTK 书籍的说明进行操作。在第 5 章（N-Gram 标记）中可以找到以下代码：

>>> from nltk.corpus import brown
>>> brown_tagged_sents = brown.tagged_sents(categories='news')
>>> brown_sents = brown.sents(categories='news')
>>> unigram_tagger = nltk.UnigramTagger(brown_tagged_sents)
>>> unigram_tagger.tag(brown_sents[2007])
[('Various', 'JJ'), ('of', 'IN'), ('the', 'AT'), ('apartments', 'NNS'),
('are', 'BER'), ('of', 'IN'), ('the', 'AT'), ('terrace', 'NN'), ('type', 'NN'),
(',', ','), ('being', 'BEG'), ('on', 'IN'), ('the', 'AT'), ('ground', 'NN'),
('floor', 'NN'), ('so', 'QL'), ('that', 'CS'), ('entrance', 'NN'), ('is', 'BEZ'),
('direct', 'JJ'), ('.', '.')]
>>> unigram_tagger.evaluate(brown_tagged_sents)
0.9349006503968017

我正在尝试做同样的事情，但我想利用整个布朗语料库来训练一元标注器。为此，我正在尝试：

brown_tagged_sents = brown.tagged_sents()
brown_sents = brown.sents()

unigram_tagger = nltk.UnigramTagger(brown_tagged_sents)
unigram_tagger.tag(brown_sents)
unigram_tagger.evaluate(brown_tagged_sents)

但由于某种原因，我收到了错误：

Traceback (most recent call last):
  File "/Users/missogra/PycharmProjects/try/POS-Tagger-nltk.py", line 9, in <module>
    unigram_tagger.tag(brown_sents)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/nltk/tag/sequential.py", line 63, in tag
    tags.append(self.tag_one(tokens, i, tags))
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/nltk/tag/sequential.py", line 83, in tag_one
    tag = tagger.choose_tag(tokens, index, history)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/nltk/tag/sequential.py", line 142, in choose_tag
    return self._context_to_tag.get(context)
TypeError: unhashable type: 'list'

Process finished with exit code 1

我非常感谢任何关于为什么会发生这种情况的提示。

pyhon 3.5 版

提前谢谢你。

Answer 1

感谢 Patrick Artner 的回答，我设法像这样解决了我的问题：

brown_tagged_sents = brown.tagged_sents()
brown_sents = brown.sents()

unigram_tagger = nltk.UnigramTagger(brown_tagged_sents)
data = [tuple(sent) for sent in brown_sents]

unigram_tagger.tag(data)
print(unigram_tagger.evaluate(brown_tagged_sents))