Fix for #3483: model_to_graphviz now works with shared variables (#3490)

* fix for 3483 + modified test_model_grah.py to test it

* fixed model_graph.py to handle shardvars

* adding import for theano

Author: sidravi1

pymc3/model_graph.py

@@ -161,6 +161,8 @@ def make_graph(self):
                               '\tconda install -c conda-forge python-graphviz')
         graph = graphviz.Digraph(self.model.name)
         for shape, var_names in self.get_plates().items():
+            if isinstance(shape, SharedVariable):
+                shape = shape.eval()
             label = ' x '.join(map('{:,d}'.format, shape))
             if label:
                 # must be preceded by 'cluster' to get a box around it

pymc3/tests/test_model_graph.py

@@ -1,7 +1,7 @@
 import numpy as np
 import pymc3 as pm
+import theano as th
 from pymc3.model_graph import ModelGraph, model_to_graphviz
-
 from .helpers import SeededTest
 
 
@@ -14,6 +14,8 @@ def radon_model():
     floor_measure = np.random.randint(0, 2, size=n_homes)
     log_radon = np.random.normal(1, 1, size=n_homes)
 
+    floor_measure = th.shared(floor_measure)
+
     d, r = divmod(919, 85)
     county = np.hstack((
         np.tile(np.arange(counties, dtype=int), d),