Erstes einen Baum zu navigieren, sehen How to iterate through all nodes of a tree? und How to navigate a nltk.tree.Tree?:
>>> from nltk.tree import Tree
>>> bracket_parse = "(S (VP (VB get) (NP (PRP me)) (ADVP (RB now))))"
>>> ptree = Tree.fromstring(bracket_parse)
>>> ptree
Tree('S', [Tree('VP', [Tree('VB', ['get']), Tree('NP', [Tree('PRP', ['me'])]), Tree('ADVP', [Tree('RB', ['now'])])])])
>>> for subtree in ptree.subtrees():
... print subtree
...
(S (VP (VB get) (NP (PRP me)) (ADVP (RB now))))
(VP (VB get) (NP (PRP me)) (ADVP (RB now)))
(VB get)
(NP (PRP me))
(PRP me)
(ADVP (RB now))
(RB now)
Und was Sie suchen ist https://github.com/nltk/nltk/blob/develop/nltk/tree.py#L341:
>>> ptree.productions()
[S -> VP, VP -> VB NP ADVP, VB -> 'get', NP -> PRP, PRP -> 'me', ADVP -> RB, RB -> 'now']
Beachten Sie, dass Tree.productions()
gibt ein Production
Objekt finden https://github.com/nltk/nltk/blob/develop/nltk/tree.py#L22 und https://github.com/nltk/nltk/blob/develop/nltk/grammar.py#L236.
Wenn Sie eine Zeichenfolge Form der Grammatikregeln möchten, können Sie entweder tun:
>>> for rule in ptree.productions():
... print rule
...
S -> VP
VP -> VB NP ADVP
VB -> 'get'
NP -> PRP
PRP -> 'me'
ADVP -> RB
RB -> 'now'
Oder
>>> rules = [str(p) for p in ptree.productions()]
>>> rules
['S -> VP', 'VP -> VB NP ADVP', "VB -> 'get'", 'NP -> PRP', "PRP -> 'me'", 'ADVP -> RB', "RB -> 'now'"]