[Enhancement] Support try_import for mmdet (#1408)

* add try-import for mmdet

* revise import logic

* add unit test for try_import

Co-authored-by: Yanhong Zeng <zengyh1900@gmail.com>
Co-authored-by: Yifei Yang <2744335995@qq.com>

mmedit/datasets/transforms/crop.py

@@ -7,14 +7,15 @@
 import numpy as np
 import torch
 from mmcv.transforms import BaseTransform
-from mmdet.apis import inference_detector, init_detector
 from mmengine.hub import get_config
 from mmengine.registry import DefaultScope
 from mmengine.utils import is_list_of, is_tuple_of
 from torch.nn.modules.utils import _pair
 
 from mmedit.registry import TRANSFORMS
-from mmedit.utils import get_box_info, random_choose_unknown
+from mmedit.utils import get_box_info, random_choose_unknown, try_import
+
+mmdet_apis = try_import('mmdet.apis')
 
 
 @TRANSFORMS.register_module()
@@ -943,9 +944,13 @@ def __init__(self,
                  box_num_upbound=-1,
                  finesize=256):
 
+        assert mmdet_apis is not None, (
+            "Cannot import 'mmdet'. Please install 'mmdet' via "
+            "\"mim install 'mmdet >= 3.0.0rc2'\".")
+
         cfg = get_config(config_file, pretrained=True)
         with DefaultScope.overwrite_default_scope('mmdet'):
-            self.predictor = init_detector(cfg, cfg.model_path)
+            self.predictor = mmdet_apis.init_detector(cfg, cfg.model_path)
 
         self.key = key
         self.box_num_upbound = box_num_upbound
@@ -1018,7 +1023,8 @@ def predict_bbox(self, image):
 
         with DefaultScope.overwrite_default_scope('mmdet'):
             with torch.no_grad():
-                results = inference_detector(self.predictor, l_stack)
+                results = mmdet_apis.inference_detector(
+                    self.predictor, l_stack)
 
         bboxes = results.pred_instances.bboxes.cpu().numpy().astype(np.int32)
         scores = results.pred_instances.scores.cpu().numpy()

mmedit/utils/__init__.py

@@ -5,14 +5,14 @@
 # TODO replace with engine's API
 from .logger import print_colored_log
 from .sampler import get_sampler
-from .setup_env import register_all_modules
+from .setup_env import register_all_modules, try_import
 from .trans_utils import (add_gaussian_noise, adjust_gamma, bbox2mask,
                           brush_stroke_mask, get_irregular_mask, make_coord,
                           random_bbox, random_choose_unknown)
 from .typing import ForwardInputs, LabelVar, NoiseVar, SampleList
 
 __all__ = [
-    'modify_args', 'print_colored_log', 'register_all_modules',
+    'modify_args', 'print_colored_log', 'register_all_modules', 'try_import',
     'ForwardInputs', 'SampleList', 'NoiseVar', 'LabelVar', 'MMEDIT_CACHE_DIR',
     'download_from_url', 'get_sampler', 'tensor2img', 'random_choose_unknown',
     'add_gaussian_noise', 'adjust_gamma', 'make_coord', 'bbox2mask',

mmedit/utils/setup_env.py

@@ -1,6 +1,9 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 import datetime
+import importlib
 import warnings
+from types import ModuleType
+from typing import Optional
 
 from mmengine import DefaultScope
 
@@ -39,3 +42,19 @@ def register_all_modules(init_default_scope: bool = True) -> None:
             # avoid name conflict
             new_instance_name = f'mmedit-{datetime.datetime.now()}'
             DefaultScope.get_instance(new_instance_name, scope_name='mmedit')
+
+
+def try_import(name: str) -> Optional[ModuleType]:
+    """Try to import a module.
+
+    Args:
+        name (str): Specifies what module to import in absolute or relative
+            terms (e.g. either pkg.mod or ..mod).
+    Returns:
+        ModuleType or None: If importing successfully, returns the imported
+        module, otherwise returns None.
+    """
+    try:
+        return importlib.import_module(name)
+    except ImportError:
+        return None

tests/test_utils/test_setup_env.py

@@ -1,6 +1,12 @@
 # Copyright (c) OpenMMLab. All rights reserved.
-from mmedit.utils import register_all_modules
+from mmedit.utils import register_all_modules, try_import
 
 
 def test_register_all_modules():
     register_all_modules()
+
+
+def test_try_import():
+    import numpy as np
+    assert try_import('numpy') is np
+    assert try_import('numpy111') is None