Source code for nltk.tag.util

# Natural Language Toolkit: Tagger Utilities
#
# Copyright (C) 2001-2017 NLTK Project
# Author: Edward Loper <edloper@gmail.com>
#         Steven Bird <stevenbird1@gmail.com>
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT

[docs]def str2tuple(s, sep='/'): """ Given the string representation of a tagged token, return the corresponding tuple representation. The rightmost occurrence of *sep* in *s* will be used to divide *s* into a word string and a tag string. If *sep* does not occur in *s*, return (s, None). >>> from nltk.tag.util import str2tuple >>> str2tuple('fly/NN') ('fly', 'NN') :type s: str :param s: The string representation of a tagged token. :type sep: str :param sep: The separator string used to separate word strings from tags. """ loc = s.rfind(sep) if loc >= 0: return (s[:loc], s[loc+len(sep):].upper()) else: return (s, None)
[docs]def tuple2str(tagged_token, sep='/'): """ Given the tuple representation of a tagged token, return the corresponding string representation. This representation is formed by concatenating the token's word string, followed by the separator, followed by the token's tag. (If the tag is None, then just return the bare word string.) >>> from nltk.tag.util import tuple2str >>> tagged_token = ('fly', 'NN') >>> tuple2str(tagged_token) 'fly/NN' :type tagged_token: tuple(str, str) :param tagged_token: The tuple representation of a tagged token. :type sep: str :param sep: The separator string used to separate word strings from tags. """ word, tag = tagged_token if tag is None: return word else: assert sep not in tag, 'tag may not contain sep!' return '%s%s%s' % (word, sep, tag)
[docs]def untag(tagged_sentence): """ Given a tagged sentence, return an untagged version of that sentence. I.e., return a list containing the first element of each tuple in *tagged_sentence*. >>> from nltk.tag.util import untag >>> untag([('John', 'NNP'), ('saw', 'VBD'), ('Mary', 'NNP')]) ['John', 'saw', 'Mary'] """ return [w for (w, t) in tagged_sentence]