nltk.parse.featurechart.FeatureChart

class documentation

class FeatureChart(Chart): (source)

Known subclasses: nltk.parse.earleychart.FeatureIncrementalChart, nltk.parse.featurechart.InstantiateVarsChart

Constructor: FeatureChart(tokens)

View In Hierarchy

A Chart for feature grammars. :see: Chart for more information.

Method parses Return an iterator of the complete tree structures that span the entire chart, and whose root node is root.
Method select Returns an iterator over the edges in this chart. See Chart.select for more information about the restrictions on the edges.
Method _add_index A helper function for select, which creates a new index for a given set of attributes (aka restriction keys).
Method _get_type_if_possible Helper function which returns the TYPE feature of the item, if it exists, otherwise it returns the item itself
Method _register_with_indexes A helper function for insert, which registers the new edge with all existing indexes.

Inherited from Chart:

Method __init__ Construct a new chart. The chart is initialized with the leaf edges corresponding to the terminal leaves.
Method child_pointer_lists Return the set of child pointer lists for the given edge. Each child pointer list is a list of edges that have been used to form this edge.
Method dot_digraph Undocumented
Method edges Return a list of all edges in this chart. New edges that are added to the chart after the call to edges() will not be contained in this list.
Method initialize Clear the chart.
Method insert Add a new edge to the chart, and return True if this operation modified the chart. In particular, return true iff the chart did not already contain edge, or if it did not already associate child_pointer_lists...
Method insert_with_backpointer Add a new edge to the chart, using a pointer to the previous edge.
Method iteredges Return an iterator over the edges in this chart. It is not guaranteed that new edges which are added to the chart before the iterator is exhausted will also be generated.
Method leaf Return the leaf value of the word at the given index.
Method leaves Return a list of the leaf values of each word in the chart's sentence.
Method num_edges Return the number of edges contained in this chart.
Method num_leaves Return the number of words in this chart's sentence.
Method pretty_format Return a pretty-printed string representation of this chart.
Method pretty_format_edge Return a pretty-printed string representation of a given edge in this chart.
Method pretty_format_leaves Return a pretty-printed string representation of this chart's leaves. This string can be used as a header for calls to pretty_format_edge.
Method trees Return an iterator of the tree structures that are associated with edge.
Method _append_edge Undocumented
Method _trees A helper function for trees.
Instance Variable _edge_to_cpls A dictionary mapping each edge to a set of child pointer lists that are associated with that edge.
Instance Variable _edges A list of the edges in the chart
Instance Variable _indexes A dictionary mapping tuples of edge attributes to indices, where each index maps the corresponding edge attribute values to lists of edges.
Instance Variable _num_leaves The number of tokens.
Instance Variable _tokens The sentence that the chart covers.
def parses(self, start, tree_class=Tree): (source)
overrides nltk.parse.chart.Chart.parses

Return an iterator of the complete tree structures that span the entire chart, and whose root node is root.

def select(self, **restrictions): (source)
overrides nltk.parse.chart.Chart.select
overridden in nltk.parse.earleychart.FeatureIncrementalChart

Returns an iterator over the edges in this chart. See Chart.select for more information about the restrictions on the edges.

def _add_index(self, restr_keys): (source)
overrides nltk.parse.chart.Chart._add_index
overridden in nltk.parse.earleychart.FeatureIncrementalChart

A helper function for select, which creates a new index for a given set of attributes (aka restriction keys).

def _get_type_if_possible(self, item): (source)

Helper function which returns the TYPE feature of the item, if it exists, otherwise it returns the item itself

def _register_with_indexes(self, edge): (source)
overrides nltk.parse.chart.Chart._register_with_indexes
overridden in nltk.parse.earleychart.FeatureIncrementalChart

A helper function for insert, which registers the new edge with all existing indexes.