Source code for nltk.tree.parsing

# Natural Language Toolkit: Text Trees
#
# Copyright (C) 2001-2022 NLTK Project
# Author: Edward Loper <edloper@gmail.com>
#         Steven Bird <stevenbird1@gmail.com>
#         Peter Ljunglöf <peter.ljunglof@gu.se>
#         Tom Aarsen <>
# URL: <https://www.nltk.org/>
# For license information, see LICENSE.TXT

import re

from nltk.tree.tree import Tree

######################################################################
## Parsing
######################################################################


[docs]def bracket_parse(s): """ Use Tree.read(s, remove_empty_top_bracketing=True) instead. """ raise NameError("Use Tree.read(s, remove_empty_top_bracketing=True) instead.")
[docs]def sinica_parse(s): """ Parse a Sinica Treebank string and return a tree. Trees are represented as nested brackettings, as shown in the following example (X represents a Chinese character): S(goal:NP(Head:Nep:XX)|theme:NP(Head:Nhaa:X)|quantity:Dab:X|Head:VL2:X)#0(PERIODCATEGORY) :return: A tree corresponding to the string representation. :rtype: Tree :param s: The string to be converted :type s: str """ tokens = re.split(r"([()| ])", s) for i in range(len(tokens)): if tokens[i] == "(": tokens[i - 1], tokens[i] = ( tokens[i], tokens[i - 1], ) # pull nonterminal inside parens elif ":" in tokens[i]: fields = tokens[i].split(":") if len(fields) == 2: # non-terminal tokens[i] = fields[1] else: tokens[i] = "(" + fields[-2] + " " + fields[-1] + ")" elif tokens[i] == "|": tokens[i] = "" treebank_string = " ".join(tokens) return Tree.fromstring(treebank_string, remove_empty_top_bracketing=True)
# s = re.sub(r'^#[^\s]*\s', '', s) # remove leading identifier # s = re.sub(r'\w+:', '', s) # remove role tags # return s __all__ = [ "bracket_parse", "sinica_parse", ]