Package nltk :: Module grammar :: Class Production

type Production

object --+
         |
        Production

Known Subclasses:

A grammar production. Each production maps a single symbol on the left-hand side to a sequence of symbols on the right-hand side. (In the case of context-free productions, the left-hand side must be a Nonterminal, and the right-hand side is a sequence of terminals and Nonterminals.) terminals can be any immutable hashable object that is not a Nonterminal. Typically, terminals are strings representing words, such as "dog" or "under".

See Also:: ContextFreeGrammar, DependencyGrammar, Nonterminal

Instance Methods

[hide private]

__init__(self, lhs, rhs)
Construct a new Production. source code

Nonterminal

lhs(self)
Returns: the left-hand side of this Production. source code

sequence of (Nonterminal and (terminal))

rhs(self)
Returns: the right-hand side of this Production. source code

integer

__len__(self)
Returns: the length of the right-hand side.

source code

bool

is_nonlexical(self)
Returns: True if the right-hand side only contains Nonterminals source code

bool

is_lexical(self)
Returns: True if the right-hand contain at least one terminal token

source code

string

__str__(self)
Returns: A verbose string representation of the Production. source code

string

__repr__(self)
Returns: A concise string representation of the Production. source code

boolean

__eq__(self, other)
Returns: true if this Production is equal to other. source code

__ne__(self, other)

source code

__cmp__(self, other)

source code

int

__hash__(self)
Returns: A hash value for the Production. source code

Instance Variables

[hide private]

Nonterminal _lhs
The left-hand side of the production.

tuple of (Nonterminal and (terminal)) _rhs
The right-hand side of the production.

Method Details

[hide private]

init(self, lhs, rhs)
(Constructor)

source code

Construct a new Production.

Parameters:

lhs (Nonterminal) - The left-hand side of the new Production.
rhs (sequence of (Nonterminal and (terminal))) - The right-hand side of the new Production.

Overrides: object.__init__