Package nltk_lite :: Package contrib :: Package mit :: Package six863 :: Package parse :: Module chart :: Class SteppingChartParse

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Class SteppingChartParse

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        object --+            
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   __init__.ParseI --+        
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__init__.AbstractParse --+    
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                ChartParse --+
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                            SteppingChartParse

A ChartParse that allows you to step through the parsing process, adding a single edge at a time. It also allows you to change the parser's strategy or grammar midway through parsing a text.

The initialize method is used to start parsing a text. step adds a single edge to the chart. set_strategy changes the strategy used by the chart parser. parses returns the set of parses that has been found by the chart parser.

Instance Methods

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__init__(self, grammar, strategy=None, trace=0)
Create a new chart parser, that uses grammar to parse texts. source code

initialize(self, tokens)
Begin parsing the given tokens.

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step(self)
Returns: A generator that adds edges to the chart, one at a time.

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_parse(self)
A generator that implements the actual parsing algorithm.

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strategy(self)
Returns: The strategy used by this parser.

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grammar(self)
Returns: The grammar used by this parser.

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chart(self)
Returns: The chart that is used by this parser.

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current_chartrule(self)
Returns: The chart rule used to generate the most recent edge.

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parses(self, tree_class=<class 'nltk_lite.parse.tree.Tree'>)
Returns: The parse trees currently contained in the chart.

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set_strategy(self, strategy)
Change the startegy that the parser uses to decide which edges to add to the chart.

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set_grammar(self, grammar)
Change the grammar used by the parser.

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set_chart(self, chart)
Load a given chart into the chart parser.

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list of Tree

get_parse_list(self, token, tree_class=<class 'nltk_lite.parse.tree.Tree'>)
Returns: A list of the parse trees for the sentence.

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Inherited from __init__.AbstractParse: batch_test, get_parse, parse

Inherited from __init__.ParseI: get_parse_dict, get_parse_probs

Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __str__

Instance Variables

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_restart
Records whether the parser's strategy, grammar, or chart has been changed.

Properties

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Inherited from object: __class__

Method Details

[hide private]

init(self, grammar, strategy=None, trace=0)
(Constructor)

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Create a new chart parser, that uses grammar to parse texts.

Overrides: ChartParse.__init__: (inherited documentation)

step(self)

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Returns:

A generator that adds edges to the chart, one at a time. Each time the generator is resumed, it adds a single edge and yields that edge. If no more edges can be added, then it yields None.

If the parser's strategy, grammar, or chart is changed, then the generator will continue adding edges using the new strategy, grammar, or chart.

Note that this generator never terminates, since the grammar or strategy might be changed to values that would add new edges. Instead, it yields None when no more edges can be added with the current strategy and grammar.

_parse(self)

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A generator that implements the actual parsing algorithm. step iterates through this generator, and restarts it whenever the parser's strategy, grammar, or chart is modified.

strategy(self)

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Returns:: The strategy used by this parser.

grammar(self)

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Returns:: The grammar used by this parser.
Overrides: __init__.AbstractParse.grammar

chart(self)

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Returns:: The chart that is used by this parser.

current_chartrule(self)

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Returns:: The chart rule used to generate the most recent edge.

parses(self, tree_class=<class 'nltk_lite.parse.tree.Tree'>)

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Returns:: The parse trees currently contained in the chart.

set_strategy(self, strategy)

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Change the startegy that the parser uses to decide which edges to add to the chart.

Parameters:

strategy (list of ChartRuleI) - A list of rules that should be used to decide what edges to add to the chart.

get_parse_list(self, token, tree_class=<class 'nltk_lite.parse.tree.Tree'>)

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Returns: list of Tree: A list of the parse trees for the sentence. When possible, this list should be sorted from most likely to least likely.
Overrides: ChartParse.get_parse_list

Instance Variable Details

[hide private]

_restart

Records whether the parser's strategy, grammar, or chart has been changed. If so, then step must restart the parsing algorithm.

Class SteppingChartParse

__init__(self, grammar, strategy=None, trace=0) (Constructor)

step(self)

_parse(self)

strategy(self)

grammar(self)

chart(self)

current_chartrule(self)

parses(self, tree_class=<class 'nltk_lite.parse.tree.Tree'>)

set_strategy(self, strategy)

get_parse_list(self, token, tree_class=<class 'nltk_lite.parse.tree.Tree'>)

_restart

init(self, grammar, strategy=None, trace=0)
(Constructor)