Package nltk :: Package model :: Module ngram :: Class NgramModel

Class NgramModel

object --+    
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api.ModelI --+
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            NgramModel

A processing interface for assigning a probability to the next word.

Instance Methods

[hide private]

__init__(self, n, train, estimator=None)
Creates an ngram language model to capture patterns in n consecutive words of training text.

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prob(self, word, context)
Evaluate the probability of this word in this context.

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_alpha(self, tokens)

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_beta(self, tokens)

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generate(self, num_words, context=())
Generate random text based on the language model. source code

_generate_one(self, context)

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entropy(self, text)
Evaluate the total entropy of a text with respect to the model.

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__contains__(self, item)

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__getitem__(self, item)

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__repr__(self)
repr(x)

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Inherited from api.ModelI: choose_random_word, logprob

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

Properties

[hide private]

Inherited from object: __class__

Method Details

[hide private]

init(self, n, train, estimator=None)
(Constructor)

source code

Creates an ngram language model to capture patterns in n consecutive words of training text. An estimator smooths the probabilities derived from the text and may allow generation of ngrams not seen during training.

Parameters:

n (int) - the order of the language model (ngram size)
train (list of list of string) - the training text
estimator (a function that takes a ConditionalFreqDist and returns a ConditionalProbDist) - a function for generating a probability distribution

Overrides: api.ModelI.__init__