Add DropPath (stochastic depth) to RegNet

Author: rwightman

timm/models/regnet.py

@@ -18,7 +18,7 @@
 
 from timm.data import IMAGENET_DEFAULT_MEAN, IMAGENET_DEFAULT_STD
 from .helpers import build_model_with_cfg
-from .layers import ClassifierHead, AvgPool2dSame, ConvBnAct, SEModule
+from .layers import ClassifierHead, AvgPool2dSame, ConvBnAct, SEModule, DropPath
 from .registry import register_model
 
 
@@ -195,14 +195,15 @@ class RegStage(nn.Module):
     """Stage (sequence of blocks w/ the same output shape)."""
 
     def __init__(self, in_chs, out_chs, stride, dilation, depth, bottle_ratio, group_width,
-                 block_fn=Bottleneck, se_ratio=0.):
+                 block_fn=Bottleneck, se_ratio=0., drop_path_rate=None, drop_block=None):
         super(RegStage, self).__init__()
         block_kwargs = {}  # FIXME setup to pass various aa, norm, act layer common args
         first_dilation = 1 if dilation in (1, 2) else 2
         for i in range(depth):
             block_stride = stride if i == 0 else 1
             block_in_chs = in_chs if i == 0 else out_chs
             block_dilation = first_dilation if i == 0 else dilation
+            drop_path = DropPath(drop_path_rate[i]) if drop_path_rate is not None else None
             if (block_in_chs != out_chs) or (block_stride != 1):
                 proj_block = downsample_conv(block_in_chs, out_chs, 1, block_stride, block_dilation)
             else:
@@ -212,7 +213,7 @@ def __init__(self, in_chs, out_chs, stride, dilation, depth, bottle_ratio, group
             self.add_module(
                 name, block_fn(
                     block_in_chs, out_chs, block_stride, block_dilation, bottle_ratio, group_width, se_ratio,
-                    downsample=proj_block, **block_kwargs)
+                    downsample=proj_block, drop_block=drop_block, drop_path=drop_path, **block_kwargs)
             )
 
     def forward(self, x):
@@ -229,7 +230,7 @@ class RegNet(nn.Module):
     """
 
     def __init__(self, cfg, in_chans=3, num_classes=1000, output_stride=32, global_pool='avg', drop_rate=0.,
-                 zero_init_last_bn=True):
+                 drop_path_rate=0., zero_init_last_bn=True):
         super().__init__()
         # TODO add drop block, drop path, anti-aliasing, custom bn/act args
         self.num_classes = num_classes
@@ -244,7 +245,7 @@ def __init__(self, cfg, in_chans=3, num_classes=1000, output_stride=32, global_p
         # Construct the stages
         prev_width = stem_width
         curr_stride = 2
-        stage_params = self._get_stage_params(cfg, output_stride=output_stride)
+        stage_params = self._get_stage_params(cfg, output_stride=output_stride, drop_path_rate=drop_path_rate)
         se_ratio = cfg['se_ratio']
         for i, stage_args in enumerate(stage_params):
             stage_name = "s{}".format(i + 1)
@@ -272,7 +273,7 @@ def __init__(self, cfg, in_chans=3, num_classes=1000, output_stride=32, global_p
                 if hasattr(m, 'zero_init_last_bn'):
                     m.zero_init_last_bn()
 
-    def _get_stage_params(self, cfg, default_stride=2, output_stride=32):
+    def _get_stage_params(self, cfg, default_stride=2, output_stride=32, drop_path_rate=0.):
         # Generate RegNet ws per block
         w_a, w_0, w_m, d = cfg['wa'], cfg['w0'], cfg['wm'], cfg['depth']
         widths, num_stages, _, _ = generate_regnet(w_a, w_0, w_m, d)
@@ -285,24 +286,26 @@ def _get_stage_params(self, cfg, default_stride=2, output_stride=32):
         stage_bottle_ratios = [cfg['bottle_ratio'] for _ in range(num_stages)]
         stage_strides = []
         stage_dilations = []
-        total_stride = 2
+        net_stride = 2
         dilation = 1
         for _ in range(num_stages):
-            if total_stride >= output_stride:
+            if net_stride >= output_stride:
                 dilation *= default_stride
                 stride = 1
             else:
                 stride = default_stride
-                total_stride *= stride
+                net_stride *= stride
             stage_strides.append(stride)
             stage_dilations.append(dilation)
+        stage_dpr = np.split(np.linspace(0, drop_path_rate, d), np.cumsum(stage_depths[:-1]))
 
         # Adjust the compatibility of ws and gws
         stage_widths, stage_groups = adjust_widths_groups_comp(stage_widths, stage_bottle_ratios, stage_groups)
-        param_names = ['out_chs', 'stride', 'dilation', 'depth', 'bottle_ratio', 'group_width']
+        param_names = ['out_chs', 'stride', 'dilation', 'depth', 'bottle_ratio', 'group_width', 'drop_path_rate']
         stage_params = [
             dict(zip(param_names, params)) for params in
-            zip(stage_widths, stage_strides, stage_dilations, stage_depths, stage_bottle_ratios, stage_groups)]
+            zip(stage_widths, stage_strides, stage_dilations, stage_depths, stage_bottle_ratios, stage_groups,
+                stage_dpr)]
         return stage_params
 
     def get_classifier(self):