Belief Engine (indra.belief)

class indra.belief.BeliefEngine(prior_probs=None)[source]

Assigns beliefs to INDRA Statements based on supporting evidence.

Parameters:prior_probs (Optional[dict[dict]]) – A dictionary of prior probabilities used to override/extend the default ones. There are two types of prior probabilities: rand and syst corresponding to random error and systematic error rate for each knowledge source. The prior_probs dictionary has the general structure {‘rand’: {‘s1’: pr1, ..., ‘sn’: prn}, ‘syst’: {‘s1’: ps1, ..., ‘sn’: psn}} where ‘s1’ ... ‘sn’ are names of input sources and pr1 ... prn and ps1 ... psn are error probabilities. Examples: {‘rand’: {‘some_source’: 0.1}} sets the random error rate for some_source to 0.1; {‘rand’: {‘’}}
prior_probs

dict[dict] – A dictionary of prior systematic and random error probabilities for each knowledge source.

set_hierarchy_probs(statements)[source]

Sets hierarchical belief probabilities for a list of INDRA Statements.

The Statements are assumed to be in a hierarchical relation graph with the supports and supported_by attribute of each Statement object having been set. The hierarchical belief probability of each Statement is calculated based on its prior probability and the probabilities propagated from Statements supporting it in the hierarchy graph.

Parameters:statements (list[indra.statements.Statement]) – A list of INDRA Statements whose belief scores are to be calculated. Each Statement object’s belief attribute is updated by this function.
set_linked_probs(linked_statements)[source]

Sets the belief probabilities for a list of linked INDRA Statements.

The list of LinkedStatement objects is assumed to come from the MechanismLinker. The belief probability of the inferred Statement is assigned the joint probability of its source Statements.

Parameters:linked_statements (list[indra.mechlinker.LinkedStatement]) – A list of INDRA LinkedStatements whose belief scores are to be calculated. The belief attribute of the inferred Statement in the LinkedStatement object is updated by this function.
set_prior_probs(statements)[source]

Sets the prior belief probabilities for a list of INDRA Statements.

The Statements are assumed to be de-duplicated. In other words, each Statement in the list passed to this function is assumed to have a list of Evidence objects that support it. The prior probability of each Statement is calculated based on the number of Evidences it has and their sources.

Parameters:statements (list[indra.statements.Statement]) – A list of INDRA Statements whose belief scores are to be calculated. Each Statement object’s belief attribute is updated by this function.
indra.belief.sample_statements(stmts, seed=None)[source]

Return statements sampled according to belief.

Statements are sampled independently according to their belief scores. For instance, a Staement with a belief score of 0.7 will end up in the returned Statement list with probability 0.7.

Parameters:
  • stmts (list[indra.statements.Statement]) – A list of INDRA Statements to sample.
  • seed (Optional[int]) – A seed for the random number generator used for sampling.
Returns:

new_stmts – A list of INDRA Statements that were chosen by random sampling according to their respective belief scores.

Return type:

list[indra.statements.Statement]