Add functionality and tests for adding moderator variables to the gra…

…ph even if they are not also declared as IVs in the query. This change enables correct inference of random effects for interaction effects

tests/test_graph.py

@@ -317,7 +317,28 @@ def test_add_interaction_effects(self):
 
         # Check that the interaction effect inherits from Student unit
         self.assertTrue(gr.has_edge(student, lhs, "has"))
-
+
+    def test_interaction_effect_variables_not_as_ivs(self):
+        u = ts.Unit("Unit")
+        a = u.nominal("Measure A", cardinality=2) # A is between-subjects
+        b = u.nominal("Measure B", cardinality=2) # B is between-subjects
+        c = u.nominal("Measure C", cardinality=2, number_of_instances=2) # B is within-subjects
+        dv = u.numeric("Dependent variable")
+
+        a.moderates(moderator=[b, c], on=dv)
+
+        design = ts.Design(dv=dv, ivs=[a, b])
+        gr = design.graph
+
+        variables = [u, a, b, c, dv]
+        self.assertEqual(len(gr.get_variables()), len(variables) + 1) # + 1 for interaction node that is created
+        for v in variables: 
+            self.assertIn(v, gr.get_variables())
+        self.assertTrue(gr.has_edge(u, a, "has"))
+        self.assertTrue(gr.has_edge(u, b, "has"))
+        self.assertTrue(gr.has_edge(u, c, "has"))
+        self.assertTrue(gr.has_edge(u, dv, "has"))
+
     def test_specify_non_nesting_relationship(self):
         participant = ts.Unit("participant id", cardinality=12) # 12 participants
         condition = participant.nominal("condition", cardinality=2, number_of_instances=2)

tisane/graph.py

@@ -362,7 +362,6 @@ def update_edge(
     def add_identifier(self, identifier: AbstractVariable):
         self._add_variable(variable=identifier, is_identifier=True)
 
-    # TODO: Add repetitions for between/within; I think make repetitions an int not a variable
     def add_relationship(
         self, relationship: Union[Has, Nests, Associates, Causes, Moderates]
     ):
@@ -469,6 +468,17 @@ def moderates(
         on: AbstractVariable,
         moderates_obj: Moderates,
     ):
+        # First make sure that all the moderators are in the graph itself 
+        for m in moderator: 
+            if isinstance(m, Measure): 
+                # Get identifier for each moderator
+                identifier = m.get_unit()
+                assert(identifier is not None)
+                # If the moderator is not in the graph, add it first
+                if not self.has_edge(start=identifier, end=m, edge_type="has"): 
+                    relationship = m.get_unit_relationsihp()
+                    self.has(identifier, m, relationship, repetitions=relationship.repetitions)
+
         # Create new interaction variable
         m_names = [m.name for m in moderator]
         name = "*".join(m_names)
@@ -496,8 +506,6 @@ def moderates(
                     variable=identifier, measure=var, repetitions=m_cardinality
                 )
                 self.has(identifier, var, relationship, repetitions=m_cardinality)
-            # else:
-            #     import pdb; pdb.set_trace()
 
     # Add an ambiguous/contribute edge to the graph
     def contribute(self, lhs: AbstractVariable, rhs: AbstractVariable):

tisane/variable.py

@@ -216,6 +216,24 @@ def has(self, measure: AbstractVariable, number_of_instances: typing.Union[int,
         self.relationships.append(has_relat)
         measure.relationships.append(has_relat)
 
+    # @returns the unit this measure is an attribute of
+    def get_unit(self) -> Unit: 
+        for r in self.relationships: 
+            if isinstance(r, Has): 
+                if r.measure is self and isinstance(r.variable, Unit): 
+                    return r.variable
+
+        return None
+
+    # @returns the unit relationship, None otherwise
+    def get_unit_relationsihp(self) -> "Has": 
+        for r in self.relationships: 
+            if isinstance(r, Has): 
+                if r.measure is self and isinstance(r.variable, Unit): 
+                    return r
+
+        return None
+
 
 
 """
@@ -403,14 +421,14 @@ def __init__(self, moderator: List[AbstractVariable], on: AbstractVariable):
 class Has:
     variable: AbstractVariable
     measure: AbstractVariable
-    repetitions: int
+    repetitions: "NumberValue"
     according_to: AbstractVariable
 
     def __init__(
         self,
         variable: AbstractVariable,
         measure: AbstractVariable,
-        repetitions: int,
+        repetitions: "NumberValue",
         **kwargs,
     ):
         self.variable = variable