NLTK：如何将名词短语遍历到 return 个字符串列表？

Question

在 NLTK 中，我如何遍历一个已解析的句子到 return 名词短语字符串列表？

我有两个目标：
(1) 创建名词短语列表而不是使用 'traverse()' 方法打印它们。我目前使用 StringIO 来记录现有 traverse() 方法的输出。这不是一个可接受的解决方案。
(2) 对名词短语字符串进行反解析：'(NP Michael/NNP Jackson/NNP)'变为'Michael Jackson'。 NLTK 中有反解析的方法吗？

NLTK 文档建议使用 traverse() 来查看名词短语，但是如何在这种递归方法中捕获 't' 以便生成字符串名词短语列表？

from nltk.tag import pos_tag

def traverse(t):
  try:
      t.label()
  except AttributeError:
      return
  else:
      if t.label() == 'NP': print(t)  # or do something else
      else:
          for child in t: 
              traverse(child)

def nounPhrase(tagged_sent):
    # Tag sentence for part of speech
    tagged_sent = pos_tag(sentence.split())  # List of tuples with [(Word, PartOfSpeech)]
    # Define several tag patterns
    grammar = r"""
      NP: {<DT|PP$>?<JJ>*<NN>}   # chunk determiner/possessive, adjectives and noun
      {<NNP>+}                # chunk sequences of proper nouns
      {<NN>+}                 # chunk consecutive nouns
      """
    cp = nltk.RegexpParser(grammar)  # Define Parser
    SentenceTree = cp.parse(tagged_sent)
    NounPhrases = traverse(SentenceTree)   # collect Noun Phrase
    return(NounPhrases)

sentence = "Michael Jackson likes to eat at McDonalds"
tagged_sent = pos_tag(sentence.split())  
NP = nounPhrase(tagged_sent)  
print(NP)

目前打印：
(NP Michael/NNP Jackson/NNP)
(NP McDonalds/NNP)
并将 'None' 存储到 NP

Answer 1

def extract_np(psent):
  for subtree in psent.subtrees():
    if subtree.label() == 'NP':
      yield ' '.join(word for word, tag in subtree.leaves())


cp = nltk.RegexpParser(grammar)
parsed_sent = cp.parse(tagged_sent)
for npstr in extract_np(parsed_sent):
    print (npstr)

NLTK：如何将名词短语遍历到 return 个字符串列表？

NLTK: How do I traverse a noun phrase to return list of strings?

python

parsing

recursion

nltk

traversal