nltk.grammar.Nonterminal

class documentation

class Nonterminal(object): (source)

Known subclasses: nltk.grammar.FeatStructNonterminal

Constructor: Nonterminal(symbol)

A non-terminal symbol for a context free grammar. Nonterminal is a wrapper class for node values; it is used by Production objects to distinguish node values from leaf values. The node value that is wrapped by a Nonterminal is known as its "symbol". Symbols are typically strings representing phrasal categories (such as "NP" or "VP"). However, more complex symbol types are sometimes used (e.g., for lexicalized grammars). Since symbols are node values, they must be immutable and hashable. Two Nonterminals are considered equal if their symbols are equal.

See Also
`CFG`, `Production`

Method	`__div__`	Return a new nonterminal whose symbol is `A/B`, where `A` is the symbol for this nonterminal, and `B` is the symbol for rhs.
Method	`__eq__`	Return True if this non-terminal is equal to `other`. In particular, return True if `other` is a `Nonterminal` and this non-terminal's symbol is equal to `other` 's symbol.
Method	`__hash__`	Undocumented
Method	`__init__`	Construct a new non-terminal from the given symbol.
Method	`__lt__`	Undocumented
Method	`__ne__`	Undocumented
Method	`__repr__`	Return a string representation for this `Nonterminal`.
Method	`__str__`	Return a string representation for this `Nonterminal`.
Method	`__truediv__`	Return a new nonterminal whose symbol is `A/B`, where `A` is the symbol for this nonterminal, and `B` is the symbol for rhs. This function allows use of the slash `/` operator with the future import of division.
Method	`symbol`	Return the node value corresponding to this `Nonterminal`.
Instance Variable	`_symbol`	The node value corresponding to this `Nonterminal`. This value must be immutable and hashable.

def __div__(self, rhs): (source) ¶

Return a new nonterminal whose symbol is A/B, where A is the symbol for this nonterminal, and B is the symbol for rhs.

Parameters
rhs:Nonterminal	The nonterminal used to form the right hand side of the new nonterminal.
Returns
Nonterminal	Undocumented

def __eq__(self, other): (source) ¶

Return True if this non-terminal is equal to other. In particular, return True if other is a Nonterminal and this non-terminal's symbol is equal to other 's symbol.

Returns
bool	Undocumented

def __hash__(self): (source) ¶

overridden in nltk.grammar.FeatStructNonterminal

Undocumented

def __init__(self, symbol): (source) ¶

Construct a new non-terminal from the given symbol.

Parameters
symbol:any	The node value corresponding to this `Nonterminal`. This value must be immutable and hashable.

def __lt__(self, other): (source) ¶

Undocumented

def __ne__(self, other): (source) ¶

Undocumented

def __repr__(self): (source) ¶

Return a string representation for this Nonterminal.

Returns
str	Undocumented

def __str__(self): (source) ¶

Return a string representation for this Nonterminal.

Returns
str	Undocumented

def __truediv__(self, rhs): (source) ¶

Return a new nonterminal whose symbol is A/B, where A is the symbol for this nonterminal, and B is the symbol for rhs. This function allows use of the slash / operator with the future import of division.

Parameters
rhs:Nonterminal	The nonterminal used to form the right hand side of the new nonterminal.
Returns
Nonterminal	Undocumented

def symbol(self): (source) ¶

overridden in nltk.grammar.FeatStructNonterminal

Return the node value corresponding to this Nonterminal.

Returns
(any)	Undocumented

_symbol: any = (source) ¶

The node value corresponding to this Nonterminal. This value must be immutable and hashable.