Package nltk :: Module probability :: Class CrossValidationProbDist

type CrossValidationProbDist

object --+    
         |    
 ProbDistI --+
             |
            CrossValidationProbDist

The cross-validation estimate for the probability distribution of the experiment used to generate a set of frequency distribution. The cross-validation estimate for the probability of a sample is found by averaging the held-out estimates for the sample in each pair of frequency distributions.

Instance Methods

[hide private]

__init__(self, freqdists, bins)
Use the cross-validation estimate to create a probability distribution for the experiment used to generate freqdists. source code

list of FreqDist

freqdists(self)
Returns: The list of frequency distributions that this ProbDist is based on. source code

list

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

source code

float

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

source code

float

discount(self)
Returns: The ratio by which counts are discounted on average: c*/c

source code

string

__repr__(self)
Returns: A string representation of this ProbDist. source code

Inherited from ProbDistI: generate, logprob, max

Class Variables

[hide private]

SUM_TO_ONE = False
True if the probabilities of the samples in this probability distribution will always sum to one.

Method Details

[hide private]

init(self, freqdists, bins)
(Constructor)

source code

Use the cross-validation estimate to create a probability distribution for the experiment used to generate freqdists.

Parameters:

freqdists (list of FreqDist) - A list of the frequency distributions generated by the experiment.
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().

Overrides: ProbDistI.__init__

freqdists(self)

source code

Returns: list of FreqDist: The list of frequency distributions that this ProbDist is based on.

samples(self)

source code

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)