Use torch.utils.tensorboard instead of tensorboardX (#108)

* use torch.utils.tensorboard instead of tensorboardX

* add backward compatibility

* add .idea to gitignore

.gitignore

@@ -103,6 +103,10 @@ venv.bak/
 # mypy
 .mypy_cache/
 
+# editors and IDEs
+.idea/
+.vscode/
+
 # custom
 mmcv/video/optflow_warp/flow_warp_module.cpp
 

mmcv/runner/hooks/logger/tensorboard.py

 import os.path as osp
 
+import torch
+
 from ...utils import master_only
 from .base import LoggerHook
 
@@ -17,15 +19,23 @@ class TensorboardLoggerHook(LoggerHook):
 
     @master_only
     def before_run(self, runner):
-        try:
-            from tensorboardX import SummaryWriter
-        except ImportError:
-            raise ImportError('Please install tensorflow and tensorboardX '
-                              'to use TensorboardLoggerHook.')
+        if torch.__version__ >= '1.1':
+            try:
+                from torch.utils.tensorboard import SummaryWriter
+            except ImportError:
+                raise ImportError(
+                    'Please run "pip install future tensorboard" to install '
+                    'the dependencies to use torch.utils.tensorboard '
+                    '(applicable to PyTorch 1.1 or higher)')
         else:
-            if self.log_dir is None:
-                self.log_dir = osp.join(runner.work_dir, 'tf_logs')
-            self.writer = SummaryWriter(self.log_dir)
+            try:
+                from tensorboardX import SummaryWriter
+            except ImportError:
+                raise ImportError('Please install tensorboardX to use '
+                                  'TensorboardLoggerHook.')
+        if self.log_dir is None:
+            self.log_dir = osp.join(runner.work_dir, 'tf_logs')
+        self.writer = SummaryWriter(self.log_dir)
 
     @master_only
     def log(self, runner):