fix generate parameter format (#3175)

docs/archive_en_US/Tutorial/SearchSpaceSpec.md

@@ -89,4 +89,4 @@ Known Limitations:
 
 * Note that for nested search space:
 
-    * Only Random Search/TPE/Anneal/Evolution tuner supports nested search space
+    * Only Random Search/TPE/Anneal/Evolution/Grid Search tuner supports nested search space

docs/en_US/Tutorial/SearchSpaceSpec.rst

@@ -255,4 +255,4 @@ Known Limitations:
   Note that for nested search space:
 
 
-  * Only Random Search/TPE/Anneal/Evolution tuner supports nested search space
+  * Only Random Search/TPE/Anneal/Evolution/Grid Search tuner supports nested search space

nni/algorithms/hpo/gridsearch_tuner/gridsearch_tuner.py

@@ -169,7 +169,7 @@ class GridSearchTuner(Tuner):
         """
         self.count += 1
         while self.count <= len(self.expanded_search_space) - 1:
-            _params_tuple = convert_dict2tuple(self.expanded_search_space[self.count])
+            _params_tuple = convert_dict2tuple(copy.deepcopy(self.expanded_search_space[self.count]))
             if _params_tuple in self.supplement_data:
                 self.count += 1
             else:
@@ -203,6 +203,6 @@ class GridSearchTuner(Tuner):
             if not _value:
                 logger.info("Useless trial data, value is %s, skip this trial data.", _value)
                 continue
-            _params_tuple = convert_dict2tuple(_params)
+            _params_tuple = convert_dict2tuple(copy.deepcopy(_params))
             self.supplement_data[_params_tuple] = True
         logger.info("Successfully import data to grid search tuner.")

nni/utils.py

@@ -109,6 +109,7 @@ def extract_scalar_history(trial_history, scalar_key='default'):
 def convert_dict2tuple(value):
     """
     convert dict type to tuple to solve unhashable problem.
+    NOTE: this function will change original data.
     """
     if isinstance(value, dict):
         for _keys in value: