Updated function with warning when multiple variables with same name are defined

Author: Raj-Parekh24

pytensor/graph/basic.py

@@ -581,11 +581,18 @@ def convert_string_keys_to_pytensor_variables(self, inputs_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:
+                length_of_nodes_with_matching_names = len(nodes_with_matching_names)
+                if length_of_nodes_with_matching_names == 0:
                     raise Exception(f"{i} not found in graph")
                 else:
+                    if length_of_nodes_with_matching_names > 1:
+                        warnings.warn(
+                            f"Found {length_of_nodes_with_matching_names} pytensor variables with name {i} taking the first declared named variable for computation"
+                        )
                     process_input_to_values[
-                        nodes_with_matching_names[0]
+                        nodes_with_matching_names[
+                            length_of_nodes_with_matching_names - 1
+                        ]
                     ] = inputs_to_values[i]
             else:
                 process_input_to_values[i] = inputs_to_values[i]

tests/graph/test_basic.py

@@ -290,9 +290,11 @@ def test_outputs_clients(self):
 
 class TestEval:
     def setup_method(self):
-        self.x, self.y = scalars("x", "y")
+        self.x, self.y, self.e = scalars("x", "y", "e")
         self.z = self.x + self.y
         self.w = 2 * self.z
+        self.t = self.e + 1
+        self.t.name = "e"
 
     def test_eval(self):
         assert self.w.eval({self.x: 1.0, self.y: 2.0}) == 6.0
@@ -303,12 +305,11 @@ def test_eval(self):
         ), "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({"x": 1.0, self.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"
+
+    def test_eval_with_strings_with_mulitple_same_name(self):
+        assert self.t.eval({"e": 1.0}) == 2.0
 
 
 class TestAutoName: