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| from collections import OrderedDict | |
| import torch.nn as nn | |
| from .bn import ABN, ACT_LEAKY_RELU, ACT_ELU, ACT_NONE | |
| import torch.nn.functional as functional | |
| class ResidualBlock(nn.Module): | |
| """Configurable residual block | |
| Parameters | |
| ---------- | |
| in_channels : int | |
| Number of input channels. | |
| channels : list of int | |
| Number of channels in the internal feature maps. Can either have two or three elements: if three construct | |
| a residual block with two `3 x 3` convolutions, otherwise construct a bottleneck block with `1 x 1`, then | |
| `3 x 3` then `1 x 1` convolutions. | |
| stride : int | |
| Stride of the first `3 x 3` convolution | |
| dilation : int | |
| Dilation to apply to the `3 x 3` convolutions. | |
| groups : int | |
| Number of convolution groups. This is used to create ResNeXt-style blocks and is only compatible with | |
| bottleneck blocks. | |
| norm_act : callable | |
| Function to create normalization / activation Module. | |
| dropout: callable | |
| Function to create Dropout Module. | |
| """ | |
| def __init__(self, | |
| in_channels, | |
| channels, | |
| stride=1, | |
| dilation=1, | |
| groups=1, | |
| norm_act=ABN, | |
| dropout=None): | |
| super(ResidualBlock, self).__init__() | |
| # Check parameters for inconsistencies | |
| if len(channels) != 2 and len(channels) != 3: | |
| raise ValueError("channels must contain either two or three values") | |
| if len(channels) == 2 and groups != 1: | |
| raise ValueError("groups > 1 are only valid if len(channels) == 3") | |
| is_bottleneck = len(channels) == 3 | |
| need_proj_conv = stride != 1 or in_channels != channels[-1] | |
| if not is_bottleneck: | |
| bn2 = norm_act(channels[1]) | |
| bn2.activation = ACT_NONE | |
| layers = [ | |
| ("conv1", nn.Conv2d(in_channels, channels[0], 3, stride=stride, padding=dilation, bias=False, | |
| dilation=dilation)), | |
| ("bn1", norm_act(channels[0])), | |
| ("conv2", nn.Conv2d(channels[0], channels[1], 3, stride=1, padding=dilation, bias=False, | |
| dilation=dilation)), | |
| ("bn2", bn2) | |
| ] | |
| if dropout is not None: | |
| layers = layers[0:2] + [("dropout", dropout())] + layers[2:] | |
| else: | |
| bn3 = norm_act(channels[2]) | |
| bn3.activation = ACT_NONE | |
| layers = [ | |
| ("conv1", nn.Conv2d(in_channels, channels[0], 1, stride=1, padding=0, bias=False)), | |
| ("bn1", norm_act(channels[0])), | |
| ("conv2", nn.Conv2d(channels[0], channels[1], 3, stride=stride, padding=dilation, bias=False, | |
| groups=groups, dilation=dilation)), | |
| ("bn2", norm_act(channels[1])), | |
| ("conv3", nn.Conv2d(channels[1], channels[2], 1, stride=1, padding=0, bias=False)), | |
| ("bn3", bn3) | |
| ] | |
| if dropout is not None: | |
| layers = layers[0:4] + [("dropout", dropout())] + layers[4:] | |
| self.convs = nn.Sequential(OrderedDict(layers)) | |
| if need_proj_conv: | |
| self.proj_conv = nn.Conv2d(in_channels, channels[-1], 1, stride=stride, padding=0, bias=False) | |
| self.proj_bn = norm_act(channels[-1]) | |
| self.proj_bn.activation = ACT_NONE | |
| def forward(self, x): | |
| if hasattr(self, "proj_conv"): | |
| residual = self.proj_conv(x) | |
| residual = self.proj_bn(residual) | |
| else: | |
| residual = x | |
| x = self.convs(x) + residual | |
| if self.convs.bn1.activation == ACT_LEAKY_RELU: | |
| return functional.leaky_relu(x, negative_slope=self.convs.bn1.slope, inplace=True) | |
| elif self.convs.bn1.activation == ACT_ELU: | |
| return functional.elu(x, inplace=True) | |
| else: | |
| return x | |
| class IdentityResidualBlock(nn.Module): | |
| def __init__(self, | |
| in_channels, | |
| channels, | |
| stride=1, | |
| dilation=1, | |
| groups=1, | |
| norm_act=ABN, | |
| dropout=None): | |
| """Configurable identity-mapping residual block | |
| Parameters | |
| ---------- | |
| in_channels : int | |
| Number of input channels. | |
| channels : list of int | |
| Number of channels in the internal feature maps. Can either have two or three elements: if three construct | |
| a residual block with two `3 x 3` convolutions, otherwise construct a bottleneck block with `1 x 1`, then | |
| `3 x 3` then `1 x 1` convolutions. | |
| stride : int | |
| Stride of the first `3 x 3` convolution | |
| dilation : int | |
| Dilation to apply to the `3 x 3` convolutions. | |
| groups : int | |
| Number of convolution groups. This is used to create ResNeXt-style blocks and is only compatible with | |
| bottleneck blocks. | |
| norm_act : callable | |
| Function to create normalization / activation Module. | |
| dropout: callable | |
| Function to create Dropout Module. | |
| """ | |
| super(IdentityResidualBlock, self).__init__() | |
| # Check parameters for inconsistencies | |
| if len(channels) != 2 and len(channels) != 3: | |
| raise ValueError("channels must contain either two or three values") | |
| if len(channels) == 2 and groups != 1: | |
| raise ValueError("groups > 1 are only valid if len(channels) == 3") | |
| is_bottleneck = len(channels) == 3 | |
| need_proj_conv = stride != 1 or in_channels != channels[-1] | |
| self.bn1 = norm_act(in_channels) | |
| if not is_bottleneck: | |
| layers = [ | |
| ("conv1", nn.Conv2d(in_channels, channels[0], 3, stride=stride, padding=dilation, bias=False, | |
| dilation=dilation)), | |
| ("bn2", norm_act(channels[0])), | |
| ("conv2", nn.Conv2d(channels[0], channels[1], 3, stride=1, padding=dilation, bias=False, | |
| dilation=dilation)) | |
| ] | |
| if dropout is not None: | |
| layers = layers[0:2] + [("dropout", dropout())] + layers[2:] | |
| else: | |
| layers = [ | |
| ("conv1", nn.Conv2d(in_channels, channels[0], 1, stride=stride, padding=0, bias=False)), | |
| ("bn2", norm_act(channels[0])), | |
| ("conv2", nn.Conv2d(channels[0], channels[1], 3, stride=1, padding=dilation, bias=False, | |
| groups=groups, dilation=dilation)), | |
| ("bn3", norm_act(channels[1])), | |
| ("conv3", nn.Conv2d(channels[1], channels[2], 1, stride=1, padding=0, bias=False)) | |
| ] | |
| if dropout is not None: | |
| layers = layers[0:4] + [("dropout", dropout())] + layers[4:] | |
| self.convs = nn.Sequential(OrderedDict(layers)) | |
| if need_proj_conv: | |
| self.proj_conv = nn.Conv2d(in_channels, channels[-1], 1, stride=stride, padding=0, bias=False) | |
| def forward(self, x): | |
| if hasattr(self, "proj_conv"): | |
| bn1 = self.bn1(x) | |
| shortcut = self.proj_conv(bn1) | |
| else: | |
| shortcut = x.clone() | |
| bn1 = self.bn1(x) | |
| out = self.convs(bn1) | |
| out.add_(shortcut) | |
| return out | |