improve the LDSDA implementation

pyomo/contrib/gdpopt/ldsda.py

@@ -120,9 +120,7 @@ def _solve_gdp(self, model, config):
         add_transformed_boolean_variable_list(self.working_model_util_block)
 
         self._log_header(logger)
-        self.working_model_external_var_info_list = self.get_external_information(
-            self.working_model_util_block, config
-        )
+        self.get_external_information(self.working_model_util_block, config)
         self.directions = self.get_directions(self.number_of_external_variables, config)
         self.best_direction = None
         self.current_point = config.starting_point
@@ -133,14 +131,14 @@ def _solve_gdp(self, model, config):
         if not hasattr(self.working_model_util_block, 'BigM'):
             self.working_model_util_block.BigM = Suffix()
 
-        locally_optimal = False
         # Solve the initial point
         self.fix_disjunctions_with_external_var(
             self.working_model_util_block, self.current_point
         )
         _ = self._solve_rnGDP_subproblem(self.working_model, config, 'Initial point')
 
         # Main loop
+        locally_optimal = False
         while not locally_optimal:
             self.iteration += 1
             if self.any_termination_criterion_met(config):
@@ -296,15 +294,13 @@ def get_directions(self, dimension, config):
             directions.remove((0,) * dimension)
             return directions
 
-    def check_valid_neighbor(self, neighbor, external_var_info_list):
+    def check_valid_neighbor(self, neighbor):
         """Function that checks if a given neighbor is valid.
 
         Parameters
         ----------
         neighbor : list
-            the neighbor
-        external_var_info_list : list
-            the list of the external variable information
+            the neighbor to be checked
 
         Returns
         -------
@@ -317,7 +313,7 @@ def check_valid_neighbor(self, neighbor, external_var_info_list):
             external_var_value >= external_var_info.LB
             and external_var_value <= external_var_info.UB
             for external_var_value, external_var_info in zip(
-                neighbor, external_var_info_list
+                neighbor, self.working_model_util_block.external_var_info_list
             )
         ):
             return True
@@ -340,9 +336,7 @@ def neighbor_search(self, model, config):
         self.best_direction = None
         for direction in self.directions:
             neighbor = tuple(map(sum, zip(self.current_point, direction)))
-            if self.check_valid_neighbor(
-                neighbor, self.working_model_util_block.external_var_info_list
-            ):
+            if self.check_valid_neighbor(neighbor):
                 self.fix_disjunctions_with_external_var(
                     self.working_model_util_block, neighbor
                 )
@@ -370,16 +364,17 @@ def line_search(self, model, config):
         primal_improved = True
         while primal_improved:
             next_point = tuple(map(sum, zip(self.current_point, self.best_direction)))
-            if not self.check_valid_neighbor(
-                next_point, self.working_model_util_block.external_var_info_list
-            ):
+            if self.check_valid_neighbor(next_point):
+                self.fix_disjunctions_with_external_var(
+                    self.working_model_util_block, next_point
+                )
+                primal_improved = self._solve_rnGDP_subproblem(
+                    model, config, 'Line search'
+                )
+                if primal_improved:
+                    self.current_point = next_point
+            else:
                 break
-            self.fix_disjunctions_with_external_var(
-                self.working_model_util_block, next_point
-            )
-            primal_improved = self._solve_rnGDP_subproblem(model, config, 'Line search')
-            if primal_improved:
-                self.current_point = next_point
         print("Line search finished.")
 
     def handle_subproblem_result(