nltk_lite.probability.MutableProbDist

Class MutableProbDist

object --+ | ProbDistI --+ | MutableProbDist

An mutable probdist where the probabilities may be easily modified. This simply copies an existing probdist, storing the probability values in a mutable dictionary and providing an update method.

Instance Methods

[hide private]

__init__(self, prob_dist, samples, store_logs=True)
Creates the mutable probdist based on the given prob_dist and using the list of samples given.

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list

samples(self)
Returns: A list of all samples that have nonzero probabilities.

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float

prob(self, sample)
Returns: the probability for a given sample.

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float

logprob(self, sample)
Returns: the natural logarithm of the probability for a given sample.

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update(self, sample, prob, log=True)
Update the probability for the given sample.

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Inherited from ProbDistI: max

Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __str__

init(self, prob_dist, samples, store_logs=True)
(Constructor)

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Creates the mutable probdist based on the given prob_dist and using the list of samples given. These values are stored as log probabilities if the store_logs flag is set.

Parameters:

prob_dist (ProbDist) - the distribution from which to garner the probabilities
samples (sequence of any) - the complete set of samples
store_logs (bool) - whether to store the probabilities as logarithms

Overrides: ProbDistI.__init__

samples(self)

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Returns: list: A list of all samples that have nonzero probabilities. Use prob to find the probability of each sample.
Overrides: ProbDistI.samples: (inherited documentation)

prob(self, sample)

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Returns: float: the probability for a given sample. Probabilities are always real numbers in the range [0, 1].
Overrides: ProbDistI.prob: (inherited documentation)

logprob(self, sample)

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Returns: float: the natural logarithm of the probability for a given sample. Log probabilities range from negitive infinity to zero.
Overrides: ProbDistI.logprob: (inherited documentation)

update(self, sample, prob, log=True)

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Update the probability for the given sample. This may cause the object to stop being the valid probability distribution - the user must ensure that they update the sample probabilities such that all samples have probabilities between 0 and 1 and that all probabilities sum to one.

Parameters:

sample (any) - the sample for which to update the probability
prob (float) - the new probability
log (bool) - is the probability already logged

Class MutableProbDist

__init__(self, prob_dist, samples, store_logs=True) (Constructor)

samples(self)

prob(self, sample)

logprob(self, sample)

update(self, sample, prob, log=True)

init(self, prob_dist, samples, store_logs=True)
(Constructor)