nltk.parse.chart.ChartParser

class documentation

class ChartParser(ParserI): (source)

Known subclasses: nltk.parse.chart.BottomUpChartParser, nltk.parse.chart.BottomUpLeftCornerChartParser, nltk.parse.chart.LeftCornerChartParser, nltk.parse.chart.SteppingChartParser, nltk.parse.chart.TopDownChartParser, nltk.parse.earleychart.IncrementalChartParser, nltk.parse.featurechart.FeatureChartParser

Constructor: ChartParser(grammar, strategy, trace, trace_chart_width, ...)

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A generic chart parser. A "strategy", or list of ChartRuleI instances, is used to decide what edges to add to the chart. In particular, ChartParser uses the following algorithm to parse texts:

Until no new edges are added:

For each rule in strategy:

Apply rule to any applicable edges in the chart.

Return any complete parses in the chart

Method	`__init__`	Create a new chart parser, that uses `grammar` to parse texts.
Method	`chart_parse`	Return the final parse `Chart` from which all possible parse trees can be extracted.
Method	`grammar`	No summary
Method	`parse`	When possible this list is sorted from most likely to least likely.
Method	`_trace_new_edges`	Undocumented
Instance Variable	`_axioms`	Undocumented
Instance Variable	`_chart_class`	Undocumented
Instance Variable	`_grammar`	Undocumented
Instance Variable	`_inference_rules`	Undocumented
Instance Variable	`_strategy`	Undocumented
Instance Variable	`_trace`	Undocumented
Instance Variable	`_trace_chart_width`	Undocumented
Instance Variable	`_use_agenda`	Undocumented

Inherited from ParserI:

Method	`parse_all`	No summary
Method	`parse_one`	No summary
Method	`parse_sents`	Apply `self.parse()` to each element of `sents`. :rtype: iter(iter(Tree))

def __init__(self, grammar, strategy=BU_LC_STRATEGY, trace=0, trace_chart_width=50, use_agenda=True, chart_class=Chart): (source) ¶

overridden in nltk.parse.chart.BottomUpChartParser, nltk.parse.chart.BottomUpLeftCornerChartParser, nltk.parse.chart.LeftCornerChartParser, nltk.parse.chart.SteppingChartParser, nltk.parse.chart.TopDownChartParser, nltk.parse.earleychart.IncrementalChartParser, nltk.parse.featurechart.FeatureChartParser

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

Parameters
grammar:CFG	The grammar used to parse texts.
strategy:list(ChartRuleI)	A list of rules that should be used to decide what edges to add to the chart (top-down strategy by default).
trace:int	The level of tracing that should be used when parsing a text. `0` will generate no tracing output; and higher numbers will produce more verbose tracing output.
trace_chart_width:int	The default total width reserved for the chart in trace output. The remainder of each line will be used to display edges.
use_agenda:bool	Use an optimized agenda-based algorithm, if possible.
chart_class	The class that should be used to create the parse charts.

def chart_parse(self, tokens, trace=None): (source) ¶

overridden in nltk.parse.earleychart.IncrementalChartParser

Return the final parse Chart from which all possible parse trees can be extracted.

Parameters
tokens:list(str)	The sentence to be parsed
trace	Undocumented
Returns
Chart	Undocumented

def grammar(self): (source) ¶

overrides nltk.parse.api.ParserI.grammar

overridden in nltk.parse.chart.SteppingChartParser

Returns
The grammar used by this parser.

def parse(self, tokens, tree_class=Tree): (source) ¶

overrides nltk.parse.api.ParserI.parse

overridden in nltk.parse.chart.SteppingChartParser

When possible this list is sorted from most likely to least likely.

Parameters
tokens	Undocumented
tree_class	Undocumented
sent:list(str)	The sentence to be parsed
Returns
iter(Tree)	An iterator that generates parse trees for the sentence.