Allow string keys in eval utility

pytensor/graph/basic.py

@@ -558,6 +558,39 @@ def get_parents(self):
             return [self.owner]
         return []
 
+    def convert_string_keys_to_pytensor_variables(self, inputs_to_values):
+        r"""Convert the string keys to corresponding `Variable` with nearest name.
+
+        Parameters
+        ----------
+        inputs_to_values :
+            A dictionary mapping PyTensor `Variable`\s to values.
+
+        Examples
+        --------
+
+        >>> import numpy as np
+        >>> import pytensor.tensor as at
+        >>> x = at.dscalar('x')
+        >>> y = at.dscalar('y')
+        >>> z = x + y
+        >>> np.allclose(z.eval({'x' : 3, 'y' : 1}), 4)
+        True
+        """
+        process_input_to_values = {}
+        for i in inputs_to_values:
+            if isinstance(i, str):
+                nodes_with_matching_names = get_var_by_name([self], i)
+                if len(nodes_with_matching_names) == 0:
+                    raise Exception(f"{i} not found in graph")
+                else:
+                    process_input_to_values[
+                        nodes_with_matching_names[0]
+                    ] = inputs_to_values[i]
+            else:
+                process_input_to_values[i] = inputs_to_values[i]
+        return process_input_to_values
+
     def eval(self, inputs_to_values=None):
         r"""Evaluate the `Variable`.
 
@@ -597,6 +630,10 @@ def eval(self, inputs_to_values=None):
         if inputs_to_values is None:
             inputs_to_values = {}
 
+        inputs_to_values = self.convert_string_keys_to_pytensor_variables(
+            inputs_to_values
+        )
+
         if not hasattr(self, "_fn_cache"):
             self._fn_cache = dict()
 

tests/graph/test_basic.py

@@ -302,6 +302,14 @@ def test_eval(self):
             pickle.loads(pickle.dumps(self.w)), "_fn_cache"
         ), "temporary functions must not be serialized"
 
+    def test_eval_with_strings(self):
+        assert self.w.eval({"x": 1.0, "y": 2.0}) == 6.0
+        assert self.w.eval({self.z: 3}) == 6.0
+        assert hasattr(self.w, "_fn_cache"), "variable must have cache after eval"
+        assert not hasattr(
+            pickle.loads(pickle.dumps(self.w)), "_fn_cache"
+        ), "temporary functions must not be serialized"
+
 
 class TestAutoName:
     def test_auto_name(self):