Package nltk :: Package chunk :: Module regexp :: Class RegexpChunkParser

type RegexpChunkParser

       object --+        
                |        
parse.api.ParserI --+    
                    |    
     api.ChunkParserI --+
                        |
                       RegexpChunkParser

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, ChinkRule, 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.

Instance Methods

[hide private]

__init__(self, rules, chunk_node='NP', top_node='S', trace=0)
Construct a new RegexpChunkParser. source code

None

_trace_apply(self, chunkstr, verbose)
Apply each of this RegexpChunkParser's rules to chunkstr, in turn. source code

None

_notrace_apply(self, chunkstr)
Apply each of this RegexpChunkParser's rules to chunkstr, in turn. source code

Tree

parse(self, chunk_struct, trace=None)
Returns: a chunk structure that encodes the chunks in a given tagged sentence.

source code

list of RegexpChunkRule

rules(self)
Returns: the sequence of rules used by RegexpChunkParser. source code

string

__repr__(self)
Returns: a concise string representation of this RegexpChunkParser. source code

string

__str__(self)
Returns: a verbose string representation of this RegexpChunkParser. source code

Inherited from api.ChunkParserI: evaluate

Inherited from parse.api.ParserI: batch_iter_parse, batch_nbest_parse, batch_parse, batch_prob_parse, grammar, iter_parse, nbest_parse, prob_parse

Deprecated

Inherited from parse.api.ParserI: batch_test, get_parse, get_parse_dict, get_parse_list, get_parse_prob

Instance Variables

[hide private]

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

int _trace
The default level of tracing.

Method Details

[hide private]

init(self, rules, chunk_node=`'NP'`, top_node=`'S'`, trace=0)
(Constructor)

source code

Construct a new RegexpChunkParser.

Parameters:

rules (list of RegexpChunkRule) - The sequence of rules that should be used to generate the chunking for a tagged text.
chunk_node (string) - 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.
top_node (string) - 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.

Overrides: object.__init__

_trace_apply(self, chunkstr, verbose)

source code

Apply each of this RegexpChunkParser's rules 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 (boolean) - Whether output should be verbose.

Returns: None

_notrace_apply(self, chunkstr)

source code

Apply each of this RegexpChunkParser's rules to chunkstr, in turn.

Parameters:

chunkstr (ChunkString) - The chunk string to which each rule should be applied.

Returns: None

parse(self, chunk_struct, trace=None)

source code

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.

Overrides: parse.api.ParserI.parse