nltk.chunk.regexp.RegexpChunkParser

class documentation

class RegexpChunkParser(ChunkParserI): (source)

Constructor: RegexpChunkParser(rules, chunk_label, root_label, trace)

A regular expression based chunk parser. RegexpChunkParser uses a sequence of "rules" to find chunks of a single type within a text. The chunking of the text is encoded using a ChunkString, and each rule acts by modifying the chunking in the ChunkString. The rules are all implemented using regular expression matching and substitution.

The RegexpChunkRule class and its subclasses (ChunkRule, StripRule, UnChunkRule, MergeRule, and SplitRule) define the rules that are used by RegexpChunkParser. Each rule defines an apply() method, which modifies the chunking encoded by a given ChunkString.

Method	`__init__`	Construct a new `RegexpChunkParser`.
Method	`__repr__`	No summary
Method	`__str__`	No summary
Method	`parse`	No summary
Method	`rules`	No summary
Method	`_notrace_apply`	Apply each rule of this `RegexpChunkParser` to `chunkstr`, in turn.
Method	`_trace_apply`	Apply each rule of this `RegexpChunkParser` to `chunkstr`, in turn. Generate trace output between each rule. If `verbose` is true, then generate verbose output.
Instance Variable	`_chunk_label`	Undocumented
Instance Variable	`_root_label`	Undocumented
Instance Variable	`_rules`	The list of rules that should be applied to a text.
Instance Variable	`_trace`	The default level of tracing.

Inherited from ChunkParserI:

Method evaluate Score the accuracy of the chunker against the gold standard. Remove the chunking the gold standard text, rechunk it using the chunker, and return a ChunkScore object reflecting the performance of this chunk peraser.

def __init__(self, rules, chunk_label='NP', root_label='S', trace=0): (source) ¶

Construct a new RegexpChunkParser.

Parameters
rules:list(RegexpChunkRule)	The sequence of rules that should be used to generate the chunking for a tagged text.
chunk_label:str	The node value that should be used for chunk subtrees. This is typically a short string describing the type of information contained by the chunk, such as `"NP"` for base noun phrases.
root_label:str	The node value that should be used for the top node of the chunk structure.
trace:int	The level of tracing that should be used when parsing a text. `0` will generate no tracing output; `1` will generate normal tracing output; and `2` or higher will generate verbose tracing output.

def __repr__(self): (source) ¶

Returns
str	a concise string representation of this `RegexpChunkParser`.

def __str__(self): (source) ¶

Returns
str	a verbose string representation of this `RegexpChunkParser`.

def parse(self, chunk_struct, trace=None): (source) ¶

overrides nltk.chunk.api.ChunkParserI.parse

Parameters
chunk_struct:Tree	the chunk structure to be (further) chunked
trace:int	The level of tracing that should be used when parsing a text. `0` will generate no tracing output; `1` will generate normal tracing output; and `2` or highter will generate verbose tracing output. This value overrides the trace level value that was given to the constructor.
Returns
Tree	a chunk structure that encodes the chunks in a given tagged sentence. A chunk is a non-overlapping linguistic group, such as a noun phrase. The set of chunks identified in the chunk structure depends on the rules used to define this `RegexpChunkParser`.

def rules(self): (source) ¶

Returns
list(RegexpChunkRule)	the sequence of rules used by `RegexpChunkParser`.

def _notrace_apply(self, chunkstr): (source) ¶

Apply each rule of this RegexpChunkParser to chunkstr, in turn.

Parameters
chunkstr:ChunkString	The chunk string to which each rule should be applied.
Returns
None	Undocumented

def _trace_apply(self, chunkstr, verbose): (source) ¶

Apply each rule of this RegexpChunkParser to chunkstr, in turn. Generate trace output between each rule. If verbose is true, then generate verbose output.

Parameters
chunkstr:ChunkString	The chunk string to which each rule should be applied.
verbose:bool	Whether output should be verbose.
Returns
None	Undocumented

_chunk_label = (source) ¶

Undocumented

_root_label = (source) ¶

Undocumented

_rules: list(RegexpChunkRule) = (source) ¶

The list of rules that should be applied to a text.

_trace: int = (source) ¶

The default level of tracing.