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247 lines
7.9 KiB
247 lines
7.9 KiB
6 years ago
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"""Pytorch ResNet implementation tweaks
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This file is a copy of https://github.com/pytorch/vision 'resnet.py' (BSD-3-Clause) with
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additional dropout and dynamic global avg/max pool.
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"""
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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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import math
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import torch.utils.model_zoo as model_zoo
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from .adaptive_avgmax_pool import AdaptiveAvgMaxPool2d
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__all__ = ['ResNet', 'resnet18', 'resnet34', 'resnet50', 'resnet101', 'resnet152']
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model_urls = {
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'resnet18': 'https://download.pytorch.org/models/resnet18-5c106cde.pth',
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'resnet34': 'https://download.pytorch.org/models/resnet34-333f7ec4.pth',
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'resnet50': 'https://download.pytorch.org/models/resnet50-19c8e357.pth',
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'resnet101': 'https://download.pytorch.org/models/resnet101-5d3b4d8f.pth',
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'resnet152': 'https://download.pytorch.org/models/resnet152-b121ed2d.pth',
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}
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def conv3x3(in_planes, out_planes, stride=1):
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"""3x3 convolution with padding"""
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return nn.Conv2d(
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in_planes, out_planes, kernel_size=3, stride=stride, padding=1, bias=False)
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class BasicBlock(nn.Module):
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expansion = 1
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def __init__(self, inplanes, planes, stride=1, downsample=None, drop_rate=0.0):
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super(BasicBlock, self).__init__()
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self.conv1 = conv3x3(inplanes, planes, stride)
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self.bn1 = nn.BatchNorm2d(planes)
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self.relu = nn.ReLU(inplace=True)
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self.conv2 = conv3x3(planes, planes)
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self.bn2 = nn.BatchNorm2d(planes)
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self.downsample = downsample
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self.stride = stride
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self.drop_rate = drop_rate
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def forward(self, x):
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residual = x
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out = self.conv1(x)
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out = self.bn1(out)
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out = self.relu(out)
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if self.drop_rate > 0.:
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out = F.dropout(out, p=self.drop_rate, training=self.training)
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out = self.conv2(out)
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out = self.bn2(out)
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if self.downsample is not None:
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residual = self.downsample(x)
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out += residual
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out = self.relu(out)
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return out
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class Bottleneck(nn.Module):
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expansion = 4
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def __init__(self, inplanes, planes, stride=1, downsample=None, drop_rate=0.0):
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super(Bottleneck, self).__init__()
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self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
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self.bn1 = nn.BatchNorm2d(planes)
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self.conv2 = nn.Conv2d(planes, planes, kernel_size=3, stride=stride,
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padding=1, bias=False)
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self.bn2 = nn.BatchNorm2d(planes)
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self.conv3 = nn.Conv2d(planes, planes * 4, kernel_size=1, bias=False)
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self.bn3 = nn.BatchNorm2d(planes * 4)
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self.relu = nn.ReLU(inplace=True)
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self.downsample = downsample
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self.stride = stride
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self.drop_rate = drop_rate
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def forward(self, x):
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residual = x
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out = self.conv1(x)
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out = self.bn1(out)
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out = self.relu(out)
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if self.drop_rate > 0.:
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out = F.dropout(out, p=self.drop_rate, training=self.training)
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out = self.conv2(out)
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out = self.bn2(out)
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out = self.relu(out)
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out = self.conv3(out)
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out = self.bn3(out)
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if self.downsample is not None:
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residual = self.downsample(x)
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out += residual
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out = self.relu(out)
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return out
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class ResNet(nn.Module):
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def __init__(self, block, layers, num_classes=1000,
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drop_rate=0.0, block_drop_rate=0.0,
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global_pool='avg'):
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self.num_classes = num_classes
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self.inplanes = 64
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self.drop_rate = drop_rate
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self.expansion = block.expansion
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super(ResNet, self).__init__()
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self.conv1 = nn.Conv2d(3, 64, kernel_size=7, stride=2, padding=3, bias=False)
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self.bn1 = nn.BatchNorm2d(64)
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self.relu = nn.ReLU(inplace=True)
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self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
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self.layer1 = self._make_layer(block, 64, layers[0], drop_rate=block_drop_rate)
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self.layer2 = self._make_layer(block, 128, layers[1], stride=2, drop_rate=block_drop_rate)
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self.layer3 = self._make_layer(block, 256, layers[2], stride=2, drop_rate=block_drop_rate)
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self.layer4 = self._make_layer(block, 512, layers[3], stride=2, drop_rate=block_drop_rate)
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self.global_pool = AdaptiveAvgMaxPool2d(pool_type=global_pool)
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self.num_features = 512 * block.expansion
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self.fc = nn.Linear(self.num_features, num_classes)
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for m in self.modules():
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if isinstance(m, nn.Conv2d):
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n = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
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m.weight.data.normal_(0, math.sqrt(2. / n))
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elif isinstance(m, nn.BatchNorm2d):
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m.weight.data.fill_(1)
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m.bias.data.zero_()
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def _make_layer(self, block, planes, blocks, stride=1, drop_rate=0.):
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downsample = None
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if stride != 1 or self.inplanes != planes * block.expansion:
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downsample = nn.Sequential(
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nn.Conv2d(self.inplanes, planes * block.expansion,
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kernel_size=1, stride=stride, bias=False),
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nn.BatchNorm2d(planes * block.expansion),
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)
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layers = [block(self.inplanes, planes, stride, downsample, drop_rate)]
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self.inplanes = planes * block.expansion
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for i in range(1, blocks):
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layers.append(block(self.inplanes, planes))
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return nn.Sequential(*layers)
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def get_classifier(self):
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return self.fc
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def reset_classifier(self, num_classes, global_pool='avg'):
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self.global_pool = AdaptiveAvgMaxPool2d(pool_type=global_pool)
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self.num_classes = num_classes
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del self.fc
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if num_classes:
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self.fc = nn.Linear(512 * self.expansion, num_classes)
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else:
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self.fc = None
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def forward_features(self, x, pool=True):
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x = self.conv1(x)
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x = self.bn1(x)
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x = self.relu(x)
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x = self.maxpool(x)
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x = self.layer1(x)
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x = self.layer2(x)
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x = self.layer3(x)
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x = self.layer4(x)
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if pool:
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x = self.global_pool(x)
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x = x.view(x.size(0), -1)
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return x
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def forward(self, x):
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x = self.forward_features(x)
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if self.drop_rate > 0.:
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x = F.dropout(x, p=self.drop_rate, training=self.training)
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x = self.fc(x)
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return x
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def resnet18(pretrained=False, **kwargs):
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"""Constructs a ResNet-18 model.
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Args:
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pretrained (bool): If True, returns a model pre-trained on ImageNet
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"""
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model = ResNet(BasicBlock, [2, 2, 2, 2], **kwargs)
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if pretrained:
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model.load_state_dict(model_zoo.load_url(model_urls['resnet18']))
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return model
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def resnet34(pretrained=False, **kwargs):
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"""Constructs a ResNet-34 model.
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Args:
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pretrained (bool): If True, returns a model pre-trained on ImageNet
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"""
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model = ResNet(BasicBlock, [3, 4, 6, 3], **kwargs)
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if pretrained:
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model.load_state_dict(model_zoo.load_url(model_urls['resnet34']))
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return model
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def resnet50(pretrained=False, **kwargs):
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"""Constructs a ResNet-50 model.
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Args:
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pretrained (bool): If True, returns a model pre-trained on ImageNet
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"""
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model = ResNet(Bottleneck, [3, 4, 6, 3], **kwargs)
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if pretrained:
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model.load_state_dict(model_zoo.load_url(model_urls['resnet50']))
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return model
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def resnet101(pretrained=False, **kwargs):
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"""Constructs a ResNet-101 model.
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Args:
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pretrained (bool): If True, returns a model pre-trained on ImageNet
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"""
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model = ResNet(Bottleneck, [3, 4, 23, 3], **kwargs)
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if pretrained:
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model.load_state_dict(model_zoo.load_url(model_urls['resnet101']))
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return model
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def resnet152(pretrained=False, **kwargs):
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"""Constructs a ResNet-152 model.
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Args:
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pretrained (bool): If True, returns a model pre-trained on ImageNet
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"""
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model = ResNet(Bottleneck, [3, 8, 36, 3], **kwargs)
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if pretrained:
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model.load_state_dict(model_zoo.load_url(model_urls['resnet152']))
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return model
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