Data structures

Trees

ImmutableMultiParentedTree
ImmutableParentedTree
ImmutableProbabilisticTree
ImmutableTree
MultiParentedTree	A Tree that automatically maintains parent pointers for multi-parented trees.
ParentedTree	A Tree that automatically maintains parent pointers for single-parented trees.
bracket_parse(s)	Use Tree.read(s, remove_empty_top_bracketing=True) instead.
sinica_parse(s)	Parse a Sinica Treebank string and return a tree.
TreePrettyPrinter	Pretty-print a tree in text format, either as ASCII or Unicode.
ProbabilisticTree
chomsky_normal_form(tree[, factor, ...])
collapse_unary(tree[, collapsePOS, ...])	Collapse subtrees with a single child (ie.
un_chomsky_normal_form(tree[, expandUnary, ...])
Tree	A Tree represents a hierarchical grouping of leaves and subtrees.

Feature structures

FeatStruct	A mapping from feature identifiers to feature values, where each feature value is either a basic value (such as a string or an integer), or a nested feature structure.
FeatDict	A feature structure that acts like a Python dictionary.
FeatList	A list of feature values, where each feature value is either a basic value (such as a string or an integer), or a nested feature structure.
unify(fstruct1, fstruct2[, bindings, trace, ...])	Unify fstruct1 with fstruct2, and return the resulting feature structure.
subsumes(fstruct1, fstruct2)	Return True if fstruct1 subsumes fstruct2.
conflicts(fstruct1, fstruct2[, trace])	Return a list of the feature paths of all features which are assigned incompatible values by fstruct1 and fstruct2.
Feature	A feature identifier that's specialized to put additional constraints, default values, etc.
SlashFeature
RangeFeature
SLASH
TYPE	A feature identifier that's specialized to put additional constraints, default values, etc.
FeatStructReader

Dependency graphs

DependencyGraph

A container for the nodes and labelled edges of a dependency structure.

Grammars

Nonterminal	A non-terminal symbol for a context free grammar.
nonterminals(symbols)	Given a string containing a list of symbol names, return a list of Nonterminals constructed from those symbols.
CFG	A context-free grammar.
Production	A grammar production.
PCFG	A probabilistic context-free grammar.
ProbabilisticProduction	A probabilistic context free grammar production.
DependencyGrammar	A dependency grammar.
DependencyProduction	A dependency grammar production.
ProbabilisticDependencyGrammar
induce_pcfg(start, productions)	Induce a PCFG grammar from a list of productions.
read_grammar(input, nonterm_parser[, ...])	Return a pair consisting of a starting category and a list of Productions.

Visualizations

ProductionList
CFGEditor	A dialog window for creating and editing context free grammars.
CFGDemo
TreeView
draw_trees(*trees)	Open a new window containing a graphical diagram of the given trees.