将NLTK“干净”树转换为NLTK块结构

Question

我对python很陌生，我很难理解数据类型、概念以及它们的转换。

我有NLTK树格式的句子(从斯坦福解析器获得并转换为NLTK树)。我需要应用为NLTK块编写的函数。然而，NLTK树格式与NLTK块格式不同。这两种格式都是NLTK树，但元素结构似乎不同(见下文)。

您能帮我把NLTK树转换成NLTK块输出格式吗？

提前谢谢！

这里是一个NLTK分块输出：

(S
  (NP Pierre/NNP Vinken/NNP)
  ,/,
  (NP 61/CD years/NNS old/JJ)
  ,/,
  will/MD
  join/VB
  (NP the/DT board/NN)
  as/IN
  (NP a/DT nonexecutive/JJ director/NN Nov./NNP 29/CD)
  ./.)

现在按元素和每种元素类型打印：

class 'nltk.tree.Tree' (NP Pierre/NNP Vinken/NNP)
type 'tuple' (',', ',')
class 'nltk.tree.Tree' (NP 61/CD years/NNS old/JJ)
type 'tuple' (',', ',')
type 'tuple' ('will', 'MD')
type 'tuple' ('join', 'VB')
class 'nltk.tree.Tree' (NP the/DT board/NN)
type 'tuple' ('as', 'IN')
class 'nltk.tree.Tree' (NP a/DT nonexecutive/JJ director/NN Nov./NNP 29/CD)
type 'tuple' ('.', '.')

这里是一个NLTK“纯”树输出(与NLTK完全一样)：

(S
  (NP
    (NP (NNP Pierre) (NNP Vinken))
    (, ,)
    (ADJP (NP (CD 61) (NNS years)) (JJ old))
    (, ,))
  (VP
    (MD will)
    (VP
      (VB join)
      (NP (DT the) (NN board))
      (PP (IN as) (NP (DT a) (JJ nonexecutive) (NN director) (NNP Nov.) (CD 29)))
      ))
  (. .))

现在按元素和每种元素类型打印：

class 'nltk.tree.Tree' (NP
  (NP (NNP Pierre) (NNP Vinken))
  (, ,)
  (ADJP (NP (CD 61) (NNS years)) (JJ old))
  (, ,))
class 'nltk.tree.Tree' (NP (NNP Pierre) (NNP Vinken))
class 'nltk.tree.Tree' (NNP Pierre)
type 'str' Pierre
class 'nltk.tree.Tree' (NNP Vinken)
type 'str' Vinken
class 'nltk.tree.Tree' (, ,)
type 'str' ,
class 'nltk.tree.Tree' (ADJP (NP (CD 61) (NNS years)) (JJ old))
class 'nltk.tree.Tree' (NP (CD 61) (NNS years))
class 'nltk.tree.Tree' (CD 61)
type 'str' 61
class 'nltk.tree.Tree' (NNS years)
type 'str' years
class 'nltk.tree.Tree' (JJ old)
type 'str' old
class 'nltk.tree.Tree' (, ,)
type 'str' ,
class 'nltk.tree.Tree' (VP
  (MD will)
  (VP
    (VB join)
    (NP (DT the) (NN board))
    (PP (IN as) (NP (DT a) (JJ nonexecutive) (NN director)))
    (NP (NNP Nov.) (CD 29))))
class 'nltk.tree.Tree' (MD will)
type 'str' will
class 'nltk.tree.Tree' (VP
  (VB join)
  (NP (DT the) (NN board))
  (PP (IN as) (NP (DT a) (JJ nonexecutive) (NN director)))
  (NP (NNP Nov.) (CD 29)))
class 'nltk.tree.Tree' (VB join)
type 'str' join
class 'nltk.tree.Tree' (NP (DT the) (NN board))
class 'nltk.tree.Tree' (DT the)
type 'str' the
class 'nltk.tree.Tree' (NN board)
type 'str' board
class 'nltk.tree.Tree' (PP (IN as) (NP (DT a) (JJ nonexecutive) (NN director)))
class 'nltk.tree.Tree' (IN as)
type 'str' as
class 'nltk.tree.Tree' (NP (DT a) (JJ nonexecutive) (NN director))
class 'nltk.tree.Tree' (DT a)
type 'str' a
class 'nltk.tree.Tree' (JJ nonexecutive)
type 'str' nonexecutive
class 'nltk.tree.Tree' (NN director)
type 'str' director
class 'nltk.tree.Tree' (NP (NNP Nov.) (CD 29))
class 'nltk.tree.Tree' (NNP Nov.)
type 'str' Nov.
class 'nltk.tree.Tree' (CD 29)
type 'str' 29
class 'nltk.tree.Tree' (. .)
type 'str' .

Answer 1

部分答复(即没有编码)：

NLTK使用Tree类来表示块数据，它实际上是为任意语法树设计的。分块语句是一棵只有一个级别分组的树，因此要从完整的解析结构到块结构，除了一种非递归组之外，您需要丢弃所有的类。哪几个团体？这取决于您的应用程序，因为有不同类型的“块”(例如，命名实体)。

您的示例显示了NP块，因此您可以遍历树并省略所有结构，但NP的顶层除外(如果要将复杂的NP块分解为小的，则是最底层的)。