Lazy import of scipy.stats (#1268)

pytensor/tensor/random/basic.py

@@ -3,7 +3,6 @@
 from typing import Literal
 
 import numpy as np
-import scipy.stats as stats
 from numpy import broadcast_shapes as np_broadcast_shapes
 from numpy import einsum as np_einsum
 from numpy import sqrt as np_sqrt
@@ -21,6 +20,11 @@
 )
 
 
+# Scipy.stats is considerably slow to import
+# We import scipy.stats lazily inside `ScipyRandomVariable`
+stats = None
+
+
 try:
     broadcast_shapes = np.broadcast_shapes
 except AttributeError:
@@ -57,6 +61,9 @@ def rng_fn_scipy(cls, rng, *args, **kwargs):
 
     @classmethod
     def rng_fn(cls, *args, **kwargs):
+        global stats
+        if stats is None:
+            import scipy.stats as stats
         size = args[-1]
         res = cls.rng_fn_scipy(*args, **kwargs)