Package nltk_lite :: Package parse :: Module chunk :: Class RegexpChunkRule
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Type RegexpChunkRule

object --+
         |
        RegexpChunkRule

Known Subclasses:
ChinkRule, ChunkRule, ExpandLeftRule, ExpandRightRule, MergeRule, SplitRule, UnChunkRule

A rule specifying how to modify the chunking in a ChunkString, using a transformational regular expression. The RegexpChunkRule class itself can be used to implement any transformational rule based on regular expressions. There are also a number of subclasses, which can be used to implement simpler types of rules, based on matching regular expressions.

Each RegexpChunkRule has a regular expression and a replacement expression. When a RegexpChunkRule is applied to a ChunkString, it searches the ChunkString for any substring that matches the regular expression, and replaces it using the replacement expression. This search/replace operation has the same semantics as re.sub.

Each RegexpChunkRule also has a description string, which gives a short (typically less than 75 characters) description of the purpose of the rule.

This transformation defined by this RegexpChunkRule should only add and remove braces; it should not modify the sequence of angle-bracket delimited tags. Furthermore, this transformation may not result in nested or mismatched bracketing.
Method Summary
  __init__(self, regexp, repl, descr)
Construct a new RegexpChunkRule.
string __repr__(self)
Return a string representation of this rule.
None apply(self, chunkstr)
Apply this rule to the given ChunkString.
string descr(self)
Return a short description of the purpose and/or effect of this rule.
Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __setattr__, __str__

Method Details

__init__(self, regexp, repl, descr)
(Constructor)

Construct a new RegexpChunkRule.
Parameters:
regexp - This RegexpChunkRule's regular expression. When this rule is applied to a ChunkString, any substring that matches regexp will be replaced using the replacement string repl. Note that this must be a normal regular expression, not a tag pattern.
           (type=regexp or string)
repl - This RegexpChunkRule's replacement expression. When this rule is applied to a ChunkString, any substring that matches regexp will be replaced using repl.
           (type=string)
descr - A short description of the purpose and/or effect of this rule.
           (type=string)
Overrides:
__builtin__.object.__init__

__repr__(self)
(Representation operator)

Returns:
A string representation of this rule. This string representation has the form:
   <RegexpChunkRule: '{<IN|VB.*>}'->'<IN>'>
Note that this representation does not include the description string; that string can be accessed separately with the descr method.
           (type=string)
Overrides:
__builtin__.object.__repr__

apply(self, chunkstr)

Apply this rule to the given ChunkString. See the class reference documentation for a description of what it means to apply a rule.
Parameters:
chunkstr - The chunkstring to which this rule is applied.
           (type=ChunkString)
Returns:
None
Raises:
ValueError - If this transformation generated an invalid chunkstring.

descr(self)

Returns:
a short description of the purpose and/or effect of this rule.
           (type=string)

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