[Enhancement] Add a new argument define_metric in wandb hook (#2237)

* wandb define_metric

* add test and some fix based on mmengine PR

* fix test

* add summary warnings

* Update mmcv/runner/hooks/logger/wandb.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Update mmcv/runner/hooks/logger/wandb.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

mmcv/runner/hooks/logger/wandb.py

 # Copyright (c) OpenMMLab. All rights reserved.
 import os.path as osp
+import warnings
 from typing import Dict, Optional, Union
 
 from mmcv.utils import scandir
@@ -43,6 +44,17 @@ class WandbLoggerHook(LoggerHook):
             ``out_suffix`` will be uploaded to wandb.
             Default: ('.log.json', '.log', '.py').
             `New in version 1.4.3.`
+        define_metric_cfg (dict, optional): A dict of metrics and summaries for
+            wandb.define_metric. The key is metric and the value is summary.
+            The summary should be in ["min", "max", "mean" ,"best", "last",
+             "none"].
+            For example, if setting
+            ``define_metric_cfg={'coco/bbox_mAP': 'max'}``, the maximum value
+            of ``coco/bbox_mAP`` will be logged on wandb UI. See
+            `wandb docs <https://docs.wandb.ai/ref/python/run#define_metric>`_
+            for details.
+            Defaults to None.
+            `New in version 1.6.3.`
 
     .. _wandb:
         https://docs.wandb.ai
@@ -57,7 +69,8 @@ class WandbLoggerHook(LoggerHook):
                  by_epoch: bool = True,
                  with_step: bool = True,
                  log_artifact: bool = True,
-                 out_suffix: Union[str, tuple] = ('.log.json', '.log', '.py')):
+                 out_suffix: Union[str, tuple] = ('.log.json', '.log', '.py'),
+                 define_metric_cfg: Optional[Dict] = None):
         super().__init__(interval, ignore_last, reset_flag, by_epoch)
         self.import_wandb()
         self.init_kwargs = init_kwargs
@@ -65,6 +78,7 @@ class WandbLoggerHook(LoggerHook):
         self.with_step = with_step
         self.log_artifact = log_artifact
         self.out_suffix = out_suffix
+        self.define_metric_cfg = define_metric_cfg
 
     def import_wandb(self) -> None:
         try:
@@ -83,6 +97,15 @@ class WandbLoggerHook(LoggerHook):
             self.wandb.init(**self.init_kwargs)  # type: ignore
         else:
             self.wandb.init()  # type: ignore
+        summary_choice = ['min', 'max', 'mean', 'best', 'last', 'none']
+        if self.define_metric_cfg is not None:
+            for metric, summary in self.define_metric_cfg.items():
+                if summary not in summary_choice:
+                    warnings.warn(
+                        f'summary should be in {summary_choice}. '
+                        f'metric={metric}, summary={summary} will be skipped.')
+                self.wandb.define_metric(  # type: ignore
+                    metric, summary=summary)
 
     @master_only
     def log(self, runner) -> None:

tests/test_runner/test_hooks.py

@@ -1606,7 +1606,8 @@ def test_segmind_hook():
 def test_wandb_hook():
     sys.modules['wandb'] = MagicMock()
     runner = _build_demo_runner()
-    hook = WandbLoggerHook(log_artifact=True)
+    hook = WandbLoggerHook(
+        log_artifact=True, define_metric_cfg={'val/loss': 'min'})
     loader = DataLoader(torch.ones((5, 2)))
 
     runner.register_hook(hook)
@@ -1615,6 +1616,7 @@ def test_wandb_hook():
     shutil.rmtree(runner.work_dir)
 
     hook.wandb.init.assert_called_with()
+    hook.wandb.define_metric.assert_called_with('val/loss', summary='min')
     hook.wandb.log.assert_called_with({
         'learning_rate': 0.02,
         'momentum': 0.95