Fix for parameter fitting when expression is given as an instance of …

…Node

SRToolkit/evaluation/parameter_estimator.py

@@ -92,7 +92,11 @@ def estimate_parameters(self, expr: Union[List[str], Node]) -> Tuple[float, np.n
             If the number of constants in the expression exceeds the maximum allowed, NaN and an empty array are returned.
             If there are no constants in the expression, the RMSE is calculated directly without optimization.
         """
-        num_constants = sum([1 for t in expr if self.symbol_library.get_type(t) == "const"])
+        if isinstance(expr, Node):
+            expr_str = expr.to_list(notation="prefix")
+            num_constants = sum([1 for t in expr_str if self.symbol_library.get_type(t) == "const"])
+        else:
+            num_constants = sum([1 for t in expr if self.symbol_library.get_type(t) == "const"])
         if 0 <= self.estimation_settings["max_constants"] < num_constants:
             return np.nan, np.array([])
 

SRToolkit/evaluation/sr_evaluator.py

@@ -105,7 +105,11 @@ def evaluate_expr(self, expr: Union[List[str], Node]) -> float:
                 f"Maximum number of evaluations ({self.max_evaluations}) reached. Stopping evaluation.")
             return np.nan
         else:
-            expr_str = "".join(expr)
+            if isinstance(expr, Node):
+                expr_list = expr.to_list(symbol_library=self.symbol_library)
+            else:
+                expr_list = expr
+            expr_str = "".join(expr_list)
             if expr_str in self.models:
                 # print(f"Already evaluated {expr_str}")
                 # print(self.models[expr_str])
@@ -115,7 +119,7 @@ def evaluate_expr(self, expr: Union[List[str], Node]) -> float:
                 self.models[expr_str] = {
                     "rmse": rmse,
                     "parameters": parameters,
-                    "expr": expr,
+                    "expr": expr_list,
                 }
                 return rmse