# Copyright (c) OpenMMLab. All rights reserved.
import torch.utils.checkpoint as cp
from mmcv.cnn import ConvModule
from mmcv.runner import BaseModule
from .se_layer import SELayer
[文档]class InvertedResidual(BaseModule):
"""Inverted Residual Block.
Args:
in_channels (int): The input channels of this Module.
out_channels (int): The output channels of this Module.
mid_channels (int): The input channels of the depthwise convolution.
kernel_size (int): The kernal size of the depthwise convolution.
Default: 3.
stride (int): The stride of the depthwise convolution. Default: 1.
se_cfg (dict): Config dict for se layer. Defaul: None, which means no
se layer.
with_expand_conv (bool): Use expand conv or not. If set False,
mid_channels must be the same with in_channels.
Default: True.
conv_cfg (dict): Config dict for convolution layer. Default: None,
which means using conv2d.
norm_cfg (dict): Config dict for normalization layer.
Default: dict(type='BN').
act_cfg (dict): Config dict for activation layer.
Default: dict(type='ReLU').
with_cp (bool): Use checkpoint or not. Using checkpoint will save some
memory while slowing down the training speed. Default: False.
init_cfg (dict or list[dict], optional): Initialization config dict.
Default: None
Returns:
Tensor: The output tensor.
"""
def __init__(self,
in_channels,
out_channels,
mid_channels,
kernel_size=3,
stride=1,
se_cfg=None,
with_expand_conv=True,
conv_cfg=None,
norm_cfg=dict(type='BN'),
act_cfg=dict(type='ReLU'),
with_cp=False,
init_cfg=None):
super(InvertedResidual, self).__init__(init_cfg)
self.with_res_shortcut = (stride == 1 and in_channels == out_channels)
assert stride in [1, 2], f'stride must in [1, 2]. ' \
f'But received {stride}.'
self.with_cp = with_cp
self.with_se = se_cfg is not None
self.with_expand_conv = with_expand_conv
if self.with_se:
assert isinstance(se_cfg, dict)
if not self.with_expand_conv:
assert mid_channels == in_channels
if self.with_expand_conv:
self.expand_conv = ConvModule(
in_channels=in_channels,
out_channels=mid_channels,
kernel_size=1,
stride=1,
padding=0,
conv_cfg=conv_cfg,
norm_cfg=norm_cfg,
act_cfg=act_cfg)
self.depthwise_conv = ConvModule(
in_channels=mid_channels,
out_channels=mid_channels,
kernel_size=kernel_size,
stride=stride,
padding=kernel_size // 2,
groups=mid_channels,
conv_cfg=conv_cfg,
norm_cfg=norm_cfg,
act_cfg=act_cfg)
if self.with_se:
self.se = SELayer(**se_cfg)
self.linear_conv = ConvModule(
in_channels=mid_channels,
out_channels=out_channels,
kernel_size=1,
stride=1,
padding=0,
conv_cfg=conv_cfg,
norm_cfg=norm_cfg,
act_cfg=None)
[文档] def forward(self, x):
def _inner_forward(x):
out = x
if self.with_expand_conv:
out = self.expand_conv(out)
out = self.depthwise_conv(out)
if self.with_se:
out = self.se(out)
out = self.linear_conv(out)
if self.with_res_shortcut:
return x + out
else:
return out
if self.with_cp and x.requires_grad:
out = cp.checkpoint(_inner_forward, x)
else:
out = _inner_forward(x)
return out