52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
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# Natural Language Toolkit: Chunk parsing API
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#
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# Copyright (C) 2001-2018 NLTK Project
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# Author: Edward Loper <edloper@gmail.com>
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# Steven Bird <stevenbird1@gmail.com> (minor additions)
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# URL: <http://nltk.org/>
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# For license information, see LICENSE.TXT
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##//////////////////////////////////////////////////////
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## Chunk Parser Interface
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##//////////////////////////////////////////////////////
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from nltk.parse import ParserI
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from nltk.chunk.util import ChunkScore
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class ChunkParserI(ParserI):
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"""
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A processing interface for identifying non-overlapping groups in
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unrestricted text. Typically, chunk parsers are used to find base
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syntactic constituents, such as base noun phrases. Unlike
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``ParserI``, ``ChunkParserI`` guarantees that the ``parse()`` method
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will always generate a parse.
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"""
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def parse(self, tokens):
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"""
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Return the best chunk structure for the given tokens
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and return a tree.
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:param tokens: The list of (word, tag) tokens to be chunked.
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:type tokens: list(tuple)
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:rtype: Tree
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"""
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raise NotImplementedError()
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def evaluate(self, gold):
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"""
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Score the accuracy of the chunker against the gold standard.
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Remove the chunking the gold standard text, rechunk it using
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the chunker, and return a ``ChunkScore`` object
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reflecting the performance of this chunk peraser.
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:type gold: list(Tree)
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:param gold: The list of chunked sentences to score the chunker on.
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:rtype: ChunkScore
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"""
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chunkscore = ChunkScore()
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for correct in gold:
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chunkscore.score(correct, self.parse(correct.leaves()))
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return chunkscore
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