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"""
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https://github.com/PaddlePaddle/PaddleDetection/blob/release/2.6/ppdet/modeling/backbones/cspresnet.py
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Copyright(c) 2023 lyuwenyu. All Rights Reserved.
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"""
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from collections import OrderedDict
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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from ...core import register
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from .common import get_activation
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__all__ = ["CSPResNet"]
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donwload_url = {
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"s": "https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_s_pretrained_from_paddle.pth",
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"m": "https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_m_pretrained_from_paddle.pth",
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"l": "https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_l_pretrained_from_paddle.pth",
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"x": "https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_x_pretrained_from_paddle.pth",
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}
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class ConvBNLayer(nn.Module):
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def __init__(self, ch_in, ch_out, filter_size=3, stride=1, groups=1, padding=0, act=None):
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super().__init__()
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self.conv = nn.Conv2d(
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ch_in, ch_out, filter_size, stride, padding, groups=groups, bias=False
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)
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self.bn = nn.BatchNorm2d(ch_out)
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self.act = get_activation(act)
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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x = self.conv(x)
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x = self.bn(x)
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x = self.act(x)
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return x
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class RepVggBlock(nn.Module):
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def __init__(self, ch_in, ch_out, act="relu", alpha: bool = False):
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super().__init__()
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self.ch_in = ch_in
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self.ch_out = ch_out
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self.conv1 = ConvBNLayer(ch_in, ch_out, 3, stride=1, padding=1, act=None)
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self.conv2 = ConvBNLayer(ch_in, ch_out, 1, stride=1, padding=0, act=None)
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self.act = get_activation(act)
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if alpha:
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self.alpha = nn.Parameter(
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torch.ones(
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1,
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)
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)
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else:
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self.alpha = None
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def forward(self, x):
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if hasattr(self, "conv"):
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y = self.conv(x)
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else:
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if self.alpha:
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y = self.conv1(x) + self.alpha * self.conv2(x)
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else:
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y = self.conv1(x) + self.conv2(x)
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y = self.act(y)
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return y
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def convert_to_deploy(self):
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if not hasattr(self, "conv"):
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self.conv = nn.Conv2d(self.ch_in, self.ch_out, 3, 1, padding=1)
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kernel, bias = self.get_equivalent_kernel_bias()
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self.conv.weight.data = kernel
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self.conv.bias.data = bias
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def get_equivalent_kernel_bias(self):
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kernel3x3, bias3x3 = self._fuse_bn_tensor(self.conv1)
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kernel1x1, bias1x1 = self._fuse_bn_tensor(self.conv2)
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if self.alpha:
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return kernel3x3 + self.alpha * self._pad_1x1_to_3x3_tensor(
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kernel1x1
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), bias3x3 + self.alpha * bias1x1
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else:
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return kernel3x3 + self._pad_1x1_to_3x3_tensor(kernel1x1), bias3x3 + bias1x1
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def _pad_1x1_to_3x3_tensor(self, kernel1x1):
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if kernel1x1 is None:
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return 0
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else:
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return F.pad(kernel1x1, [1, 1, 1, 1])
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def _fuse_bn_tensor(self, branch: ConvBNLayer):
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if branch is None:
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return 0, 0
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kernel = branch.conv.weight
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running_mean = branch.norm.running_mean
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running_var = branch.norm.running_var
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gamma = branch.norm.weight
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beta = branch.norm.bias
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eps = branch.norm.eps
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std = (running_var + eps).sqrt()
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t = (gamma / std).reshape(-1, 1, 1, 1)
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return kernel * t, beta - running_mean * gamma / std
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class BasicBlock(nn.Module):
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def __init__(self, ch_in, ch_out, act="relu", shortcut=True, use_alpha=False):
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super().__init__()
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assert ch_in == ch_out
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self.conv1 = ConvBNLayer(ch_in, ch_out, 3, stride=1, padding=1, act=act)
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self.conv2 = RepVggBlock(ch_out, ch_out, act=act, alpha=use_alpha)
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self.shortcut = shortcut
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def forward(self, x):
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y = self.conv1(x)
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y = self.conv2(y)
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if self.shortcut:
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return x + y
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else:
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return y
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class EffectiveSELayer(nn.Module):
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"""Effective Squeeze-Excitation
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From `CenterMask : Real-Time Anchor-Free Instance Segmentation` - https://arxiv.org/abs/1911.06667
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"""
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def __init__(self, channels, act="hardsigmoid"):
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super(EffectiveSELayer, self).__init__()
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self.fc = nn.Conv2d(channels, channels, kernel_size=1, padding=0)
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self.act = get_activation(act)
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def forward(self, x: torch.Tensor):
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x_se = x.mean((2, 3), keepdim=True)
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x_se = self.fc(x_se)
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x_se = self.act(x_se)
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return x * x_se
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class CSPResStage(nn.Module):
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def __init__(self, block_fn, ch_in, ch_out, n, stride, act="relu", attn="eca", use_alpha=False):
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super().__init__()
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ch_mid = (ch_in + ch_out) // 2
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if stride == 2:
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self.conv_down = ConvBNLayer(ch_in, ch_mid, 3, stride=2, padding=1, act=act)
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else:
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self.conv_down = None
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self.conv1 = ConvBNLayer(ch_mid, ch_mid // 2, 1, act=act)
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self.conv2 = ConvBNLayer(ch_mid, ch_mid // 2, 1, act=act)
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self.blocks = nn.Sequential(
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*[
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block_fn(ch_mid // 2, ch_mid // 2, act=act, shortcut=True, use_alpha=use_alpha)
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for i in range(n)
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]
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)
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if attn:
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self.attn = EffectiveSELayer(ch_mid, act="hardsigmoid")
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else:
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self.attn = None
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self.conv3 = ConvBNLayer(ch_mid, ch_out, 1, act=act)
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def forward(self, x):
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if self.conv_down is not None:
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x = self.conv_down(x)
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y1 = self.conv1(x)
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y2 = self.blocks(self.conv2(x))
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y = torch.concat([y1, y2], dim=1)
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if self.attn is not None:
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y = self.attn(y)
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y = self.conv3(y)
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return y
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@register()
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class CSPResNet(nn.Module):
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layers = [3, 6, 6, 3]
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channels = [64, 128, 256, 512, 1024]
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model_cfg = {
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"s": {
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"depth_mult": 0.33,
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"width_mult": 0.50,
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},
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"m": {
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"depth_mult": 0.67,
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"width_mult": 0.75,
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},
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"l": {
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"depth_mult": 1.00,
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"width_mult": 1.00,
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},
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"x": {
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"depth_mult": 1.33,
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"width_mult": 1.25,
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},
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}
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def __init__(
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self,
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name: str,
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act="silu",
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return_idx=[1, 2, 3],
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use_large_stem=True,
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use_alpha=False,
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pretrained=False,
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):
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super().__init__()
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depth_mult = self.model_cfg[name]["depth_mult"]
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width_mult = self.model_cfg[name]["width_mult"]
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channels = [max(round(c * width_mult), 1) for c in self.channels]
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layers = [max(round(l * depth_mult), 1) for l in self.layers]
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act = get_activation(act)
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if use_large_stem:
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self.stem = nn.Sequential(
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OrderedDict(
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[
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(
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"conv1",
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ConvBNLayer(3, channels[0] // 2, 3, stride=2, padding=1, act=act),
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),
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(
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"conv2",
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ConvBNLayer(
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channels[0] // 2, channels[0] // 2, 3, stride=1, padding=1, act=act
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),
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),
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(
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"conv3",
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ConvBNLayer(
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channels[0] // 2, channels[0], 3, stride=1, padding=1, act=act
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),
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),
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]
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)
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)
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else:
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self.stem = nn.Sequential(
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OrderedDict(
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[
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(
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"conv1",
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ConvBNLayer(3, channels[0] // 2, 3, stride=2, padding=1, act=act),
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),
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(
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"conv2",
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ConvBNLayer(
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channels[0] // 2, channels[0], 3, stride=1, padding=1, act=act
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),
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),
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]
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)
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)
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n = len(channels) - 1
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self.stages = nn.Sequential(
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OrderedDict(
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[
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(
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str(i),
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CSPResStage(
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BasicBlock,
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channels[i],
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channels[i + 1],
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layers[i],
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2,
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act=act,
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use_alpha=use_alpha,
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),
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)
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for i in range(n)
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]
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)
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)
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self._out_channels = channels[1:]
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self._out_strides = [4 * 2**i for i in range(n)]
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self.return_idx = return_idx
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if pretrained:
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if isinstance(pretrained, bool) or "http" in pretrained:
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state = torch.hub.load_state_dict_from_url(donwload_url[name], map_location="cpu")
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else:
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state = torch.load(pretrained, map_location="cpu")
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self.load_state_dict(state)
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print(f"Load CSPResNet_{name} state_dict")
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def forward(self, x):
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x = self.stem(x)
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outs = []
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for idx, stage in enumerate(self.stages):
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x = stage(x)
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if idx in self.return_idx:
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outs.append(x)
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return outs
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