[Fix] Avoid mapping unnecessary key to albu format (#1773)

mmpose/datasets/transforms/common_transforms.py

@@ -618,7 +618,6 @@ def __init__(self,
             }
         else:
             self.keymap_to_albu = keymap
-        self.keymap_back = {v: k for k, v in self.keymap_to_albu.items()}
 
     def albu_builder(self, cfg: dict) -> albumentations:
         """Import a module from albumentations.
@@ -654,23 +653,6 @@ def albu_builder(self, cfg: dict) -> albumentations:
 
         return obj_cls(**args)
 
-    @staticmethod
-    def mapper(d: dict, keymap: dict) -> dict:
-        """Dictionary mapper.
-
-        Renames keys according to keymap provided.
-
-        Args:
-            d (dict): old dict
-            keymap (dict): key mapping like {'old_key': 'new_key'}.
-
-        Returns:
-            dict: new dict.
-        """
-
-        updated_dict = {keymap.get(k, k): v for k, v in d.items()}
-        return updated_dict
-
     def transform(self, results: dict) -> dict:
         """The transform function of :class:`Albumentation` to apply
         albumentations transforms.
@@ -684,11 +666,18 @@ def transform(self, results: dict) -> dict:
             dict: updated result dict.
         """
         # map result dict to albumentations format
-        results = self.mapper(results, self.keymap_to_albu)
+        results_albu = {}
+        for k, v in self.keymap_to_albu.items():
+            assert k in results, \
+                f'The `{k}` is required to perform albumentations transforms'
+            results_albu[v] = results[k]
+
         # Apply albumentations transforms
-        results = self.aug(**results)
-        # map result dict back to the original format
-        results = self.mapper(results, self.keymap_back)
+        results_albu = self.aug(**results_albu)
+
+        # map the albu results back to the original format
+        for k, v in self.keymap_to_albu.items():
+            results[k] = results_albu[v]
 
         return results