Credal Network¶
Credal networks are probabilistic graphical models based on imprecise probability. Credal networks can be regarded as an extension of Bayesian networks, where credal sets replace probability mass functions in the specification of the local models for the network variables given their parents. As a Bayesian network defines a joint probability mass function over its variables, a credal network defines a joint credal set (from Wikipedia).
Tutorial
Reference
Model¶
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class
pyAgrum.
CredalNet
(*args)¶ Constructor used to create a CredalNet (step by step or with two BayesNet)
- CredalNet() -> CredalNet
- default constructor
CredalNet(src_min_num,src_max_den) -> CredalNet
Parameters: - src_min_num (str or pyAgrum.BayesNet) – The path to a BayesNet or the BN itself which contains lower probabilities.
- src_max_den (str or pyAgrum.BayesNet) – The (optional) path to a BayesNet or the BN itself which contains upper probabilities.
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addArc
(self, tail, head)¶ Adds an arc between two nodes
Parameters: - tail – the id of the tail node
- head (int) – the id of the head node
Raises: gum.InvalidDirectedCircle
– If any (directed) cycle is created by this arcgum.InvalidNode
– If head or tail does not belong to the graph nodesgum.DuplicateElement
– If one of the arc already exists
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addVariable
(self, name, card)¶ Parameters: - name (str) – the name of the new variable
- card (int) – the domainSize of the new variable
Returns: the id of the new node
Return type: int
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approximatedBinarization
(self)¶ Approximate binarization.
Each bit has a lower and upper probability which is the lowest - resp. highest - over all vertices of the credal set. Enlarge the orignal credal sets and may induce huge imprecision.
Warning
Enlarge the orignal credal sets and therefor induce huge imprecision by propagation. Not recommended, use MCSampling or something else instead
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bnToCredal
(self, beta, oneNet, keepZeroes=False)¶ Perturbates the BayesNet provided as input for this CredalNet by generating intervals instead of point probabilities and then computes each vertex of each credal set.
Parameters: - beta (double) – The beta used to perturbate the network
- oneNet (bool) – used as a flag. Set to True if one BayesNet if provided with counts, to False if two BayesNet are provided; one with probabilities (the lower net) and one with denominators over the first modalities (the upper net)
- keepZeroes (bool) – used as a flag as whether or not - respectively True or False - we keep zeroes as zeroes. Default is False, i.e. zeroes are not kept
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computeBinaryCPTMinMax
(self)¶
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credalNet_currentCpt
(self)¶ Warning
Experimental function - Return type to be wrapped
Returns: a constant reference to the (up-to-date) CredalNet CPTs. Return type: tbw
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credalNet_srcCpt
(self)¶ Warning
Experimental function - Return type to be wrapped
Returns: a constant reference to the (up-to-date) CredalNet CPTs. Return type: tbw
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currentNodeType
(self, id)¶ Parameters: id (int) – The constant reference to the choosen NodeId Returns: the type of the choosen node in the (up-to-date) CredalNet __current_bn if any, __src_bn otherwise. Return type: pyAgrum.CredalNet
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current_bn
(self)¶ Returns: Returs a constant reference to the actual BayesNet (used as a DAG, it’s CPTs does not matter). Return type: pyAgrum.BayesNet
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domainSize
(self, id)¶ Parameters: id (int) – The id of the node Returns: The cardinality of the node Return type: int
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epsilonMax
(self)¶ Returns: a constant reference to the highest perturbation of the BayesNet provided as input for this CredalNet. Return type: double
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epsilonMean
(self)¶ Returns: a constant reference to the average perturbation of the BayesNet provided as input for this CredalNet. Return type: double
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epsilonMin
(self)¶ Returns: a constant reference to the lowest perturbation of the BayesNet provided as input for this CredalNet. Return type: double
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fillConstraint
(self, id, entry, lower, upper)¶ fillConstraint(self, id, ins, lower, upper)
Set the interval constraints of a credal set of a given node (from an instantiation index)
Parameters: - id (int) – The id of the node
- entry (int) – The index of the instantiation excluding the given node (only the parents are used to compute the index of the credal set)
- ins (pyAgrum.Instantiation) – The Instantiation
- lower (list) – The lower value for each probability in correct order
- upper (list) – The upper value for each probability in correct order
Warning
You need to call intervalToCredal when done filling all constraints.
Warning
DOES change the BayesNet (s) associated to this credal net !
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fillConstraints
(self, id, lower, upper)¶ Set the interval constraints of the credal sets of a given node (all instantiations)
Parameters: - id (int) – The id of the node
- lower (list) – The lower value for each probability in correct order
- upper (list) – The upper value for each probability in correct order
Warning
You need to call intervalToCredal when done filling all constraints.
Warning
DOES change the BayesNet (s) associated to this credal net !
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get_binaryCPT_max
(self)¶ Warning
Experimental function - Return type to be wrapped
Returns: a constant reference to the upper probabilities of each node X over the ‘True’ modality Return type: tbw
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get_binaryCPT_min
(self)¶ Warning
Experimental function - Return type to be wrapped
Returns: a constant reference to the lower probabilities of each node X over the ‘True’ modality Return type: tbw
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hasComputedBinaryCPTMinMax
(self)¶
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idmLearning
(self, s=0, keepZeroes=False)¶ Learns parameters from a BayesNet storing counts of events.
Use this method when using a single BayesNet storing counts of events. IDM model if s > 0, standard point probability if s = 0 (default value if none precised).
Parameters: - s (int) – the IDM parameter.
- keepZeroes (bool) – used as a flag as whether or not - respectively True or False - we keep zeroes as zeroes. Default is False, i.e. zeroes are not kept.
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instantiation
(self, id)¶ Get an Instantiation from a node id, usefull to fill the constraints of the network.
bnet accessors / shortcuts.
Parameters: id (int) – the id of the node we want an instantiation from Returns: the instantiation Return type: pyAgrum.Instantiation
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intervalToCredal
(self)¶ Computes the vertices of each credal set according to their interval definition (uses lrs).
Use this method when using two BayesNet, one with lower probabilities and one with upper probabilities.
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intervalToCredalWithFiles
(self)¶ Warning
Deprecated : use intervalToCredal (lrsWrapper with no input / output files needed).
Computes the vertices of each credal set according to their interval definition (uses lrs).
Use this method when using a single BayesNet storing counts of events.
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isSeparatelySpecified
(self)¶ Returns: True if this CredalNet is separately and interval specified, False otherwise. Return type: bool
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lagrangeNormalization
(self)¶ Normalize counts of a BayesNet storing counts of each events such that no probability is 0.
Use this method when using a single BayesNet storing counts of events. Lagrange normalization. This call is irreversible and modify counts stored by __src_bn.
Doest not performs computations of the parameters but keeps normalized counts of events only. Call idmLearning to compute the probabilities (with any parameter value).
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nodeType
(self, id)¶ Parameters: id (int) – the constant reference to the choosen NodeId Returns: the type of the choosen node in the (up-to-date) CredalNet in __src_bn. Return type: pyAgrum.CredalNet
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saveBNsMinMax
(self, min_path, max_path)¶ If this CredalNet was built over a perturbed BayesNet, one can save the intervals as two BayesNet.
to call after bnToCredal(GUM_SCALAR beta) save a BN with lower probabilities and a BN with upper ones
Parameters: - min_path (str) – the path to save the BayesNet which contains the lower probabilities of each node X.
- max_path (str) – the path to save the BayesNet which contains the upper probabilities of each node X.
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setCPT
(self, id, entry, cpt)¶ setCPT(self, id, ins, cpt)
Warning
(experimental function) - Parameters to be wrapped
Set the vertices of one credal set of a given node (any instantiation index)
Parameters: - id (int) – the Id of the node
- entry (int) – the index of the instantiation (from 0 to K - 1) excluding the given node (only the parents are used to compute the index of the credal set)
- ins (pyAgrum.Instantiation) – the Instantiation (only the parents matter to find the credal set index)
- cpt (tbw) – the vertices of every credal set (for each instantiation of the parents)
Warning
DOES not change the BayesNet(s) associated to this credal net !
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setCPTs
(self, id, cpt)¶ Warning
(experimental function) - Parameters to be wrapped
Set the vertices of the credal sets (all of the conditionals) of a given node
Parameters: - id (int) – the NodeId of the node
- cpt (tbw) – the vertices of every credal set (for each instantiation of the parents)
Warning
DOES not change the BayesNet (s) associated to this credal net !
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src_bn
(self)¶ Returns: Returns a constant reference to the original BayesNet (used as a DAG, it’s CPTs does not matter). Return type: pyAgrum.BayesNet
Inference¶
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class
pyAgrum.
CNMonteCarloSampling
(credalNet: pyAgrum.CredalNet)¶ Class used for inferences in credal networks with Monte Carlo sampling algorithm.
- CNMonteCarloSampling(cn) -> CNMonteCarloSampling
- Parameters:
- cn (pyAgrum.CredalNet) – a credal network
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CN
(self)¶
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currentTime
(self)¶ Returns: get the current running time in second (double) Return type: double
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dynamicExpMax
(self, varName)¶ Get the upper dynamic expectation of a given variable prefix.
Parameters: varName (str) – the variable name prefix which upper expectation we want. Returns: a constant reference to the variable upper expectation over all time steps. Return type: double
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dynamicExpMin
(self, varName)¶ Get the lower dynamic expectation of a given variable prefix.
Parameters: varName (str) – the variable name prefix which lower expectation we want. Returns: a constant reference to the variable lower expectation over all time steps. Return type: double
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epsilon
(self)¶ Returns: the value of epsilon Return type: double
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history
(self)¶ Returns: the scheme history Return type: tuple Raises: gum.OperationNotAllowed
– If the scheme did not performed or if verbosity is set to false
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insertEvidenceFile
(self, path)¶ Insert evidence from file.
Parameters: path (str) – the path to the evidence file.
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insertModalsFile
(self, path)¶ Insert variables modalities from file to compute expectations.
Parameters: path (str) – The path to the modalities file.
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makeInference
(self)¶ Starts the inference.
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marginalMax
(self, id)¶ marginalMax(self, name) -> Potential
Get the upper marginals of a given node id.
Parameters: - id (int) – the node id which upper marginals we want.
- varName (str) – the variable name which upper marginals we want.
Returns: a constant reference to this node upper marginals.
Return type: list
Raises: gum.IndexError
– If the node does not belong to the Credal network
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marginalMin
(self, id)¶ marginalMin(self, name) -> Potential
Get the lower marginals of a given node id.
Parameters: - id (int) – the node id which lower marginals we want.
- varName (str) – the variable name which lower marginals we want.
Returns: a constant reference to this node lower marginals.
Return type: list
Raises: gum.IndexError
– If the node does not belong to the Credal network
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maxIter
(self)¶ Returns: the criterion on number of iterations Return type: int
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maxTime
(self)¶ Returns: the timeout(in seconds) Return type: double
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messageApproximationScheme
(self)¶ Returns: the approximation scheme message Return type: str
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minEpsilonRate
(self)¶ Returns: the value of the minimal epsilon rate Return type: double
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nbrIterations
(self)¶ Returns: the number of iterations Return type: int
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periodSize
(self)¶ Returns: the number of samples between 2 stopping Return type: int Raises: gum.OutOfBounds
– If p<1
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setEpsilon
(self, eps)¶ Parameters: eps (double) – the epsilon we want to use Raises: gum.OutOfBounds
– If eps<0
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setMaxIter
(self, max)¶ Parameters: max (int) – the maximum number of iteration Raises: gum.OutOfBounds
– If max <= 1
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setMaxTime
(self, timeout)¶ Parameters: tiemout (double) – stopping criterion on timeout (in seconds) Raises: gum.OutOfBounds
– If timeout<=0.0
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setMinEpsilonRate
(self, rate)¶ Parameters: rate (double) – the minimal epsilon rate
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setPeriodSize
(self, p)¶ Parameters: p (int) – number of samples between 2 stopping Raises: gum.OutOfBounds
– If p<1
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setRepetitiveInd
(self, flag)¶ Parameters: flag (bool) – True if repetitive independence is to be used, false otherwise. Only usefull with dynamic networks.
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setVerbosity
(self, v)¶ Parameters: v (bool) – verbosity
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verbosity
(self)¶ Returns: True if the verbosity is enabled Return type: bool
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class
pyAgrum.
CNLoopyPropagation
(cnet: pyAgrum.CredalNet)¶ Class used for inferences in credal networks with Loopy Propagation algorithm.
- CNLoopyPropagation(cn) -> CNLoopyPropagation
- Parameters:
- cn (pyAgrum.CredalNet) – a Credal network
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CN
(self)¶
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currentTime
(self)¶ Returns: get the current running time in second (double) Return type: double
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dynamicExpMax
(self, varName)¶ Get the upper dynamic expectation of a given variable prefix.
Parameters: varName (str) – the variable name prefix which upper expectation we want. Returns: a constant reference to the variable upper expectation over all time steps. Return type: double
-
dynamicExpMin
(self, varName)¶ Get the lower dynamic expectation of a given variable prefix.
Parameters: varName (str) – the variable name prefix which lower expectation we want. Returns: a constant reference to the variable lower expectation over all time steps. Return type: double
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epsilon
(self)¶ Returns: the value of epsilon Return type: double
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eraseAllEvidence
(self)¶ Erase all inference related data to perform another one.
You need to insert evidence again if needed but modalities are kept. You can insert new ones by using the appropriate method which will delete the old ones.
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history
(self)¶ Returns: the scheme history Return type: tuple Raises: gum.OperationNotAllowed
– If the scheme did not performed or if verbosity is set to false
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inferenceType
(self, inft)¶ inferenceType(self) -> pyAgrum.credal::CNLoopyPropagation ::InferenceType
Returns: the inference type Return type: int
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insertEvidenceFile
(self, path)¶ Insert evidence from file.
Parameters: path (str) – the path to the evidence file.
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insertModalsFile
(self, path)¶ Insert variables modalities from file to compute expectations.
Parameters: path (str) – The path to the modalities file.
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makeInference
(self)¶ Starts the inference.
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marginalMax
(self, id)¶ marginalMax(self, name) -> Potential
Get the upper marginals of a given node id.
Parameters: - id (int) – the node id which upper marginals we want.
- varName (str) – the variable name which upper marginals we want.
Returns: a constant reference to this node upper marginals.
Return type: list
Raises: gum.IndexError
– If the node does not belong to the Credal network
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marginalMin
(self, id)¶ marginalMin(self, name) -> Potential
Get the lower marginals of a given node id.
Parameters: - id (int) – the node id which lower marginals we want.
- varName (str) – the variable name which lower marginals we want.
Returns: a constant reference to this node lower marginals.
Return type: list
Raises: gum.IndexError
– If the node does not belong to the Credal network
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maxIter
(self)¶ Returns: the criterion on number of iterations Return type: int
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maxTime
(self)¶ Returns: the timeout(in seconds) Return type: double
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messageApproximationScheme
(self)¶ Returns: the approximation scheme message Return type: str
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minEpsilonRate
(self)¶ Returns: the value of the minimal epsilon rate Return type: double
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nbrIterations
(self)¶ Returns: the number of iterations Return type: int
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periodSize
(self)¶ Returns: the number of samples between 2 stopping Return type: int Raises: gum.OutOfBounds
– If p<1
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saveInference
(self, path)¶ Saves marginals.
Parameters: path (str) – The path to the file to save marginals.
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setEpsilon
(self, eps)¶ Parameters: eps (double) – the epsilon we want to use Raises: gum.OutOfBounds
– If eps<0
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setMaxIter
(self, max)¶ Parameters: max (int) – the maximum number of iteration Raises: gum.OutOfBounds
– If max <= 1
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setMaxTime
(self, timeout)¶ Parameters: tiemout (double) – stopping criterion on timeout (in seconds) Raises: gum.OutOfBounds
– If timeout<=0.0
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setMinEpsilonRate
(self, rate)¶ Parameters: rate (double) – the minimal epsilon rate
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setPeriodSize
(self, p)¶ Parameters: p (int) – number of samples between 2 stopping Raises: gum.OutOfBounds
– If p<1
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setRepetitiveInd
(self, flag)¶ Parameters: flag (bool) – True if repetitive independence is to be used, false otherwise. Only usefull with dynamic networks.
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setVerbosity
(self, v)¶ Parameters: v (bool) – verbosity
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verbosity
(self)¶ Returns: True if the verbosity is enabled Return type: bool