Allow alternative gesture mappings in subclass fetcher

Summary: Add option to specify a custom subclass id mapping. Allows for flexibility when training models with different outputs needed.

Reviewed By: sanjeevk42

Differential Revision: D26826986

fbshipit-source-id: 9dba4f0f2f2afebd2f152ddd9aebd46cf4c86a0d

d2go/modeling/subclass.py

 #!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
 
+from abc import ABC, abstractmethod
+from typing import Any, Dict, List
+import logging
 
 import numpy as np
 import torch
@@ -9,6 +12,7 @@ from torch.nn import functional as F
 
 from detectron2.layers import cat
 from detectron2.modeling import ROI_HEADS_REGISTRY, StandardROIHeads
+from detectron2.utils.registry import Registry
 from d2go.config import CfgNode as CN
 from d2go.data.dataset_mappers import (
     D2GO_DATA_MAPPER_REGISTRY,
@@ -17,22 +21,47 @@ from d2go.data.dataset_mappers import (
 from d2go.utils.helper import alias
 
 
+logger = logging.getLogger(__name__)
+
+SUBCLASS_FETCHER_REGISTRY = Registry("SUBCLASS_FETCHER")
+
 def add_subclass_configs(cfg):
     _C = cfg
     _C.MODEL.SUBCLASS = CN()
     _C.MODEL.SUBCLASS.SUBCLASS_ON = False
     _C.MODEL.SUBCLASS.NUM_SUBCLASSES = 0  # must be set
     _C.MODEL.SUBCLASS.NUM_LAYERS = 1
+    _C.MODEL.SUBCLASS.SUBCLASS_ID_FETCHER = "SubclassFetcher"  # ABC, must be set
 
 
-def fetch_subclass_from_extras(dataset_dict):
+class SubclassFetcher(ABC):
+    """ Fetcher class to read subclass id annotations from dataset and prepare for train/eval.
+        Subclass this and register with `@SUBCLASS_FETCHER_REGISTRY.register()` decorator
+        to use with custom projects.
     """
-    Retrieve subclass (eg. hand gesture per RPN region) info from dataset dict.
+
+    @property
+    @abstractmethod
+    def subclass_names(self) -> List[str]:
+        """ Overwrite this member with any new mappings' subclass names, which
+            may be useful for specific evaluation purposes.
+            len(self.subclass_names) should be equal to the expected number
+            of subclass head outputs (cfg.MODEL.SUBCLASS.NUM_SUBCLASSES + 1).
         """
+        pass
+
+    def remap(self, subclass_id: int) -> int:
+        """ Map subclass ids read from dataset to new label id """
+        return subclass_id
+
+    def fetch_subclass_ids(self, dataset_dict: Dict[str, Any]) -> List[int]:
+        """ Get all the subclass_ids in a dataset dict """
         extras_list = [anno.get("extras") for anno in dataset_dict["annotations"]]
         subclass_ids = [extras["subclass_id"] for extras in extras_list]
         return subclass_ids
 
+
+
 @D2GO_DATA_MAPPER_REGISTRY.register()
 class SubclassDatasetMapper(D2GoDatasetMapper):
     """
@@ -40,7 +69,18 @@ class SubclassDatasetMapper(D2GoDatasetMapper):
     """
     def __init__(self, cfg, is_train, tfm_gens=None, subclass_fetcher=None):
         super().__init__(cfg, is_train=is_train, tfm_gens=tfm_gens)
-        self.subclass_fetcher = subclass_fetcher or fetch_subclass_from_extras
+        if subclass_fetcher is None:
+            fetcher_name = cfg.MODEL.SUBCLASS.SUBCLASS_ID_FETCHER
+            self.subclass_fetcher = SUBCLASS_FETCHER_REGISTRY.get(fetcher_name)()
+            logger.info(
+                f"Initialized {self.__class__.__name__} with "
+                f"subclass fetcher '{self.subclass_fetcher.__class__.__name__}'"
+            )
+        else:
+            assert isinstance(subclass_fetcher, SubclassFetcher), subclass_fetcher
+            self.subclass_fetcher = subclass_fetcher
+            logger.info(f"Set subclass fetcher to {self.subclass_fetcher}")
+
         # NOTE: field doesn't exist when loading a (old) caffe2 model.
         # self.subclass_on = cfg.MODEL.SUBCLASS.SUBCLASS_ON
         self.subclass_on = True
@@ -53,7 +93,7 @@ class SubclassDatasetMapper(D2GoDatasetMapper):
         mapped_dataset_dict = super()._original_call(dataset_dict)
 
         if (self.is_train and self.subclass_on):
-            subclass_ids = self.subclass_fetcher(dataset_dict)
+            subclass_ids = self.subclass_fetcher.fetch_subclass_ids(dataset_dict)
             subclasses = torch.tensor(subclass_ids, dtype=torch.int64)
             mapped_dataset_dict["instances"].gt_subclasses = subclasses
         return mapped_dataset_dict