LGS-164 belief propagation for polytrees, special case of OR cpds, refactored from LGSv0.0.2

1 files changed, 21 insertions, 0 deletions

diff --git a/beliefs/utils/random_variables.py b/beliefs/utils/random_variables.py
new file mode 100644
index 0000000..1a0b0f7
--- /dev/null
+++ b/beliefs/utils/random_variables.py
@@ -0,0 +1,21 @@
+
+
+def get_reachable_observed_variables_for_inferred_variables(model, observed=set()):
+    """
+    After performing inference on a BayesianModel, get the labels of observed variables
+    ("reachable observed variables") that influenced the beliefs of variables inferred
+    to be in a definite state.
+
+    INPUT
+      model: instance of BayesianModel class or subclass
+      observed: set of labels (strings) corresponding to vars pinned to definite
+        state during inference.
+    RETURNS
+      dict, of form key - source label (a string), value - a list of strings
+    """
+    if not observed:
+        return {}
+
+    source_vars = model.get_unobserved_variables_in_definite_state(observed)
+
+    return {var: model.reachable_observed_variables(var, observed) for var in source_vars}