Identifying mixture sub-graphs defined with an IfElse Op

aeppl/mixture.py

@@ -10,7 +10,7 @@
     node_rewriter,
     pre_greedy_node_rewriter,
 )
-from aesara.ifelse import ifelse
+from aesara.ifelse import IfElse, ifelse
 from aesara.scalar.basic import Switch
 from aesara.tensor.basic import Join, MakeVector
 from aesara.tensor.elemwise import Elemwise
@@ -305,14 +305,14 @@ def mixture_replace(fgraph, node):
     return [new_mixture_rv]
 
 
-@node_rewriter((Elemwise,))
-def switch_mixture_replace(fgraph, node):
+@node_rewriter((Elemwise, IfElse))
+def switch_ifelse_mixture_replace(fgraph, node):
     rv_map_feature = getattr(fgraph, "preserve_rv_mappings", None)
 
     if rv_map_feature is None:
         return None  # pragma: no cover
 
-    if not isinstance(node.op.scalar_op, Switch):
+    if not isinstance(node.op, IfElse) and not isinstance(node.op.scalar_op, Switch):
         return None  # pragma: no cover
 
     old_mixture_rv = node.default_output()
@@ -420,7 +420,7 @@ def logprob_MixtureRV(
 logprob_rewrites_db.register(
     "mixture_replace",
     EquilibriumGraphRewriter(
-        [mixture_replace, switch_mixture_replace],
+        [mixture_replace, switch_ifelse_mixture_replace],
         max_use_ratio=aesara.config.optdb__max_use_ratio,
     ),
     0,

tests/test_mixture.py

@@ -3,6 +3,7 @@
 import numpy as np
 import pytest
 import scipy.stats.distributions as sp
+from aesara.ifelse import ifelse
 from aesara.graph.basic import Variable, equal_computations
 from aesara.tensor.random.basic import CategoricalRV
 from aesara.tensor.shape import shape_tuple
@@ -715,7 +716,8 @@ def test_mixture_with_DiracDelta():
     assert m_vv in logp_res
 
 
-def test_switch_mixture():
+@pytest.mark.parametrize("op", [at.switch, ifelse])
+def test_switch_ifelse_mixture(op):
     srng = at.random.RandomStream(29833)
 
     X_rv = srng.normal(-10.0, 0.1, name="X")
@@ -725,7 +727,7 @@ def test_switch_mixture():
     i_vv = I_rv.clone()
     i_vv.name = "i"
 
-    Z1_rv = at.switch(I_rv, X_rv, Y_rv)
+    Z1_rv = op(I_rv, X_rv, Y_rv)
     z_vv = Z1_rv.clone()
     z_vv.name = "z1"