nltk.probability.LaplaceProbDist

class documentation

class LaplaceProbDist(LidstoneProbDist): (source)

Constructor: LaplaceProbDist(freqdist, bins)

The Laplace estimate for the probability distribution of the experiment used to generate a frequency distribution. The "Laplace estimate" approximates the probability of a sample with count c from an experiment with N outcomes and B bins as (c+1)/(N+B). This is equivalent to adding one to the count for each bin, and taking the maximum likelihood estimate of the resulting frequency distribution.

Method	`__init__`	Use the Laplace estimate to create a probability distribution for the experiment used to generate `freqdist`.
Method	`__repr__`	No summary

Inherited from LidstoneProbDist:

Method	`discount`	Return the ratio by which counts are discounted on average: c*/c
Method	`freqdist`	Return the frequency distribution that this probability distribution is based on.
Method	`max`	Return the sample with the greatest probability. If two or more samples have the same probability, return one of them; which sample is returned is undefined.
Method	`prob`	Return the probability for a given sample. Probabilities are always real numbers in the range [0, 1].
Method	`samples`	Return a list of all samples that have nonzero probabilities. Use `prob` to find the probability of each sample.
Constant	`SUM_TO_ONE`	True if the probabilities of the samples in this probability distribution will always sum to one.
Instance Variable	`_bins`	Undocumented
Instance Variable	`_divisor`	Undocumented
Instance Variable	`_freqdist`	Undocumented
Instance Variable	`_gamma`	Undocumented
Instance Variable	`_N`	Undocumented

Inherited from ProbDistI (via LidstoneProbDist):

Method	`generate`	Return a randomly selected sample from this probability distribution. The probability of returning each sample `samp` is equal to `self.prob(samp)`.
Method	`logprob`	Return the base 2 logarithm of the probability for a given sample.

def __init__(self, freqdist, bins=None): (source) ¶

overrides nltk.probability.LidstoneProbDist.__init__

Use the Laplace estimate to create a probability distribution for the experiment used to generate freqdist.

Parameters
freqdist:FreqDist	The frequency distribution that the probability estimates should be based on.
bins:int	The number of sample values that can be generated by the experiment that is described by the probability distribution. This value must be correctly set for the probabilities of the sample values to sum to one. If `bins` is not specified, it defaults to `freqdist.B()`.

def __repr__(self): (source) ¶

overrides nltk.probability.LidstoneProbDist.__repr__

Returns
str	A string representation of this `ProbDist`.