Mark Data nodes in graph.

pymc3/model_graph.py

@@ -8,10 +8,6 @@
 from .util import get_default_varnames
 import pymc3 as pm
 
-# this is a placeholder for a better characterization of the type
-# of variables in a model.
-RV = Tensor
-
 
 class ModelGraph:
     def __init__(self, model):
@@ -30,7 +26,7 @@ def get_deterministics(self, var):
                 deterministics.append(v)
         return deterministics
 
-    def _get_ancestors(self, var, func) -> MutableSet[RV]:
+    def _get_ancestors(self, var, func) -> MutableSet[Tensor]:
         """Get all ancestors of a function, doing some accounting for deterministics.
         """
 
@@ -108,7 +104,15 @@ def _make_node(self, var_name, graph):
         if hasattr(v, 'distribution'):
             distribution = v.distribution.__class__.__name__
         else:
-            distribution = 'Deterministic'
+            is_data = False # type: bool
+            try:
+                is_data = v.is_data
+            except AttributeError:
+                pass
+            if is_data:
+                distribution = 'Data'
+            else:
+                distribution = 'Deterministic'
             attrs['shape'] = 'box'
 
         graph.node(var_name.replace(':', '&'),