103 lines
3.7 KiB
Python
103 lines
3.7 KiB
Python
# Natural Language Toolkit: Parsers
|
|
#
|
|
# Copyright (C) 2001-2019 NLTK Project
|
|
# Author: Steven Bird <stevenbird1@gmail.com>
|
|
# Edward Loper <edloper@gmail.com>
|
|
# URL: <http://nltk.org/>
|
|
# For license information, see LICENSE.TXT
|
|
#
|
|
|
|
"""
|
|
NLTK Parsers
|
|
|
|
Classes and interfaces for producing tree structures that represent
|
|
the internal organization of a text. This task is known as "parsing"
|
|
the text, and the resulting tree structures are called the text's
|
|
"parses". Typically, the text is a single sentence, and the tree
|
|
structure represents the syntactic structure of the sentence.
|
|
However, parsers can also be used in other domains. For example,
|
|
parsers can be used to derive the morphological structure of the
|
|
morphemes that make up a word, or to derive the discourse structure
|
|
for a set of utterances.
|
|
|
|
Sometimes, a single piece of text can be represented by more than one
|
|
tree structure. Texts represented by more than one tree structure are
|
|
called "ambiguous" texts. Note that there are actually two ways in
|
|
which a text can be ambiguous:
|
|
|
|
- The text has multiple correct parses.
|
|
- There is not enough information to decide which of several
|
|
candidate parses is correct.
|
|
|
|
However, the parser module does *not* distinguish these two types of
|
|
ambiguity.
|
|
|
|
The parser module defines ``ParserI``, a standard interface for parsing
|
|
texts; and two simple implementations of that interface,
|
|
``ShiftReduceParser`` and ``RecursiveDescentParser``. It also contains
|
|
three sub-modules for specialized kinds of parsing:
|
|
|
|
- ``nltk.parser.chart`` defines chart parsing, which uses dynamic
|
|
programming to efficiently parse texts.
|
|
- ``nltk.parser.probabilistic`` defines probabilistic parsing, which
|
|
associates a probability with each parse.
|
|
"""
|
|
|
|
from nltk.parse.api import ParserI
|
|
from nltk.parse.chart import (
|
|
ChartParser,
|
|
SteppingChartParser,
|
|
TopDownChartParser,
|
|
BottomUpChartParser,
|
|
BottomUpLeftCornerChartParser,
|
|
LeftCornerChartParser,
|
|
)
|
|
from nltk.parse.featurechart import (
|
|
FeatureChartParser,
|
|
FeatureTopDownChartParser,
|
|
FeatureBottomUpChartParser,
|
|
FeatureBottomUpLeftCornerChartParser,
|
|
)
|
|
from nltk.parse.earleychart import (
|
|
IncrementalChartParser,
|
|
EarleyChartParser,
|
|
IncrementalTopDownChartParser,
|
|
IncrementalBottomUpChartParser,
|
|
IncrementalBottomUpLeftCornerChartParser,
|
|
IncrementalLeftCornerChartParser,
|
|
FeatureIncrementalChartParser,
|
|
FeatureEarleyChartParser,
|
|
FeatureIncrementalTopDownChartParser,
|
|
FeatureIncrementalBottomUpChartParser,
|
|
FeatureIncrementalBottomUpLeftCornerChartParser,
|
|
)
|
|
from nltk.parse.pchart import (
|
|
BottomUpProbabilisticChartParser,
|
|
InsideChartParser,
|
|
RandomChartParser,
|
|
UnsortedChartParser,
|
|
LongestChartParser,
|
|
)
|
|
from nltk.parse.recursivedescent import (
|
|
RecursiveDescentParser,
|
|
SteppingRecursiveDescentParser,
|
|
)
|
|
from nltk.parse.shiftreduce import ShiftReduceParser, SteppingShiftReduceParser
|
|
from nltk.parse.util import load_parser, TestGrammar, extract_test_sentences
|
|
from nltk.parse.viterbi import ViterbiParser
|
|
from nltk.parse.dependencygraph import DependencyGraph
|
|
from nltk.parse.projectivedependencyparser import (
|
|
ProjectiveDependencyParser,
|
|
ProbabilisticProjectiveDependencyParser,
|
|
)
|
|
from nltk.parse.nonprojectivedependencyparser import (
|
|
NonprojectiveDependencyParser,
|
|
NaiveBayesDependencyScorer,
|
|
ProbabilisticNonprojectiveParser,
|
|
)
|
|
from nltk.parse.malt import MaltParser
|
|
from nltk.parse.evaluate import DependencyEvaluator
|
|
from nltk.parse.transitionparser import TransitionParser
|
|
from nltk.parse.bllip import BllipParser
|
|
from nltk.parse.corenlp import CoreNLPParser, CoreNLPDependencyParser
|