Package gPy :: Module Samplers :: Class DNSampler

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Class DNSampler

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For sampling from dependency networks

Instance Methods

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__init__(self, dnm, variables=None)
Construct a sampler from a dependency network

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condition(self, condition)
Make a sampler conditional on some evidence

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gibbs_sample(self, initial=None, burnin=100, iterations=1000)
Run Gibbs sampling

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uncondition(self)
Remove all evidence

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Integer

variable_index(self, variable)
Return the index for a variable in joint instantiations

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Tuple

variables(self)
Return the ordering of variables in joint instantiations

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

Instance Variables

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List _condition_index
Instantiated variables have their values, others have None

Tuple _dists
For each variable, a dictionary mapping parent instantiations to a MultinomialSampler object

Tuple _indextuple
The tuple (0,1, ...n) where n is the number of variables

Tuple _indices
For each variable, a tuple of the indices corresponding to its parents

List _instskel
A list of Nones of the right length to hold a full joint instantiation.

Dictionary _var2index
Maps a variable to its index in _variables

Tuple _variables
An ordering of the DN's variables used for example, for Gibbs sampling

Properties

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Inherited from object: __class__

Method Details

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init(self, dnm, variables=None)
(Constructor)

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Construct a sampler from a dependency network

Parameters:

dnm (Models.DN) - Dependency network
variables (Tuple) - An order in which to sample values for the variable in eg Gibbs sampling. If not supplied an arbitrary ordering is used.

Overrides: object.__init__

condition(self, condition)

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Make a sampler conditional on some evidence

Any previous conditioning will be erased.

Parameters:

condition (Dictionary) - Mapping from variables to their values

variable_index(self, variable)

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Return the index for a variable in joint instantiations

Returns: Integer: The index for a variable in joint instantiations

variables(self)

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Return the ordering of variables in joint instantiations

This will be a topological ordering for a BNSampler.

Returns: Tuple: The ordering of variables in joint instantiations

Class DNSampler

__init__(self, dnm, variables=None) (Constructor)

condition(self, condition)

variable_index(self, variable)

variables(self)

init(self, dnm, variables=None)
(Constructor)