Package nltk_lite :: Module probability :: Class ProbabilisticMixIn
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Type ProbabilisticMixIn

object --+
         |
        ProbabilisticMixIn

Known Subclasses:
ImmutableProbabilisticMixIn, ImmutableProbabilisticTree, ProbabilisticTree

A mix-in class to associate probabilities with other classes (trees, rules, etc.). To use the ProbabilisticMixIn class, define a new class that derives from an existing class and from ProbabilisticMixIn. You will need to define a new constructor for the new class, which explicitly calls the constructors of both its parent classes. For example:
>>> class A:
...     def __init__(self, x, y): self.data = (x,y)
... 
>>> class ProbabilisticA(A, ProbabilisticMixIn):
...     def __init__(self, x, y, **prob_kwarg):
...         A.__init__(self, x, y)
...         ProbabilisticMixIn.__init__(self, **prob_kwarg)

See the documentation for the ProbabilisticMixIn constructor for information about the arguments it expects.

You should generally also redefine the string representation methods, the comparison methods, and the hashing method.
Method Summary
  __init__(self, **kwargs)
Initialize this object's probability.
float logprob(self)
Return log(p), where p is the probability associated with this object.
float prob(self)
Return the probability associated with this object.
  set_logprob(self, logprob)
Set the log probability associated with this object to logprob.
  set_prob(self, prob)
Set the probability associated with this object to prob.
Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __str__

Method Details

__init__(self, **kwargs)
(Constructor)

Initialize this object's probability. This initializer should be called by subclass constructors. prob should generally be the first argument for those constructors.
Keyword Parameters:
prob - The probability associated with the object.
           (type=float)
logprob - The log of the probability associated with the object.
Overrides:
__builtin__.object.__init__

logprob(self)

Returns:
log(p), where p is the probability associated with this object.
           (type=float)

prob(self)

Returns:
The probability associated with this object.
           (type=float)

set_logprob(self, logprob)

Set the log probability associated with this object to logprob. I.e., set the probability associated with this object to exp(logprob).
Parameters:
logprob - The new log probability
           (type=float)

set_prob(self, prob)

Set the probability associated with this object to prob.
Parameters:
prob - The new probability
           (type=float)

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