File size: 6,056 Bytes
97069e1
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
import os
import sys
import torch
import torch.nn as nn
import math
try:
    from lib.nn import SynchronizedBatchNorm2d
except ImportError:
    from torch.nn import BatchNorm2d as SynchronizedBatchNorm2d
try:
    from urllib import urlretrieve
except ImportError:
    from urllib.request import urlretrieve


__all__ = ['ResNeXt', 'resnext101'] # support resnext 101


model_urls = {
    #'resnext50': 'http://sceneparsing.csail.mit.edu/model/pretrained_resnet/resnext50-imagenet.pth',
    'resnext101': 'http://sceneparsing.csail.mit.edu/model/pretrained_resnet/resnext101-imagenet.pth'
}


def conv3x3(in_planes, out_planes, stride=1):
    "3x3 convolution with padding"
    return nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride,
                     padding=1, bias=False)


class GroupBottleneck(nn.Module):
    expansion = 2

    def __init__(self, inplanes, planes, stride=1, groups=1, downsample=None):
        super(GroupBottleneck, self).__init__()
        self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
        self.bn1 = SynchronizedBatchNorm2d(planes)
        self.conv2 = nn.Conv2d(planes, planes, kernel_size=3, stride=stride,
                               padding=1, groups=groups, bias=False)
        self.bn2 = SynchronizedBatchNorm2d(planes)
        self.conv3 = nn.Conv2d(planes, planes * 2, kernel_size=1, bias=False)
        self.bn3 = SynchronizedBatchNorm2d(planes * 2)
        self.relu = nn.ReLU(inplace=True)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        residual = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)
        out = self.relu(out)

        out = self.conv3(out)
        out = self.bn3(out)

        if self.downsample is not None:
            residual = self.downsample(x)

        out += residual
        out = self.relu(out)

        return out


class ResNeXt(nn.Module):

    def __init__(self, block, layers, groups=32, num_classes=1000):
        self.inplanes = 128
        super(ResNeXt, self).__init__()
        self.conv1 = conv3x3(3, 64, stride=2)
        self.bn1 = SynchronizedBatchNorm2d(64)
        self.relu1 = nn.ReLU(inplace=True)
        self.conv2 = conv3x3(64, 64)
        self.bn2 = SynchronizedBatchNorm2d(64)
        self.relu2 = nn.ReLU(inplace=True)
        self.conv3 = conv3x3(64, 128)
        self.bn3 = SynchronizedBatchNorm2d(128)
        self.relu3 = nn.ReLU(inplace=True)
        self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)

        self.layer1 = self._make_layer(block, 128, layers[0], groups=groups)
        self.layer2 = self._make_layer(block, 256, layers[1], stride=2, groups=groups)
        self.layer3 = self._make_layer(block, 512, layers[2], stride=2, groups=groups)
        self.layer4 = self._make_layer(block, 1024, layers[3], stride=2, groups=groups)
        self.avgpool = nn.AvgPool2d(7, stride=1)
        self.fc = nn.Linear(1024 * block.expansion, num_classes)

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                n = m.kernel_size[0] * m.kernel_size[1] * m.out_channels // m.groups
                m.weight.data.normal_(0, math.sqrt(2. / n))
            elif isinstance(m, SynchronizedBatchNorm2d):
                m.weight.data.fill_(1)
                m.bias.data.zero_()

    def _make_layer(self, block, planes, blocks, stride=1, groups=1):
        downsample = None
        if stride != 1 or self.inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                nn.Conv2d(self.inplanes, planes * block.expansion,
                          kernel_size=1, stride=stride, bias=False),
                SynchronizedBatchNorm2d(planes * block.expansion),
            )

        layers = []
        layers.append(block(self.inplanes, planes, stride, groups, downsample))
        self.inplanes = planes * block.expansion
        for i in range(1, blocks):
            layers.append(block(self.inplanes, planes, groups=groups))

        return nn.Sequential(*layers)

    def forward(self, x):
        x = self.relu1(self.bn1(self.conv1(x)))
        x = self.relu2(self.bn2(self.conv2(x)))
        x = self.relu3(self.bn3(self.conv3(x)))
        x = self.maxpool(x)

        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)

        x = self.avgpool(x)
        x = x.view(x.size(0), -1)
        x = self.fc(x)

        return x


'''
def resnext50(pretrained=False, **kwargs):
    """Constructs a ResNet-50 model.

    Args:
        pretrained (bool): If True, returns a model pre-trained on Places
    """
    model = ResNeXt(GroupBottleneck, [3, 4, 6, 3], **kwargs)
    if pretrained:
        model.load_state_dict(load_url(model_urls['resnext50']), strict=False)
    return model
'''


def resnext101(pretrained=False, **kwargs):
    """Constructs a ResNet-101 model.

    Args:
        pretrained (bool): If True, returns a model pre-trained on Places
    """
    model = ResNeXt(GroupBottleneck, [3, 4, 23, 3], **kwargs)
    if pretrained:
        model.load_state_dict(load_url(model_urls['resnext101']), strict=False)
    return model


# def resnext152(pretrained=False, **kwargs):
#     """Constructs a ResNeXt-152 model.
#
#     Args:
#         pretrained (bool): If True, returns a model pre-trained on Places
#     """
#     model = ResNeXt(GroupBottleneck, [3, 8, 36, 3], **kwargs)
#     if pretrained:
#         model.load_state_dict(load_url(model_urls['resnext152']))
#     return model


def load_url(url, model_dir='./pretrained', map_location=None):
    if not os.path.exists(model_dir):
        os.makedirs(model_dir)
    filename = url.split('/')[-1]
    cached_file = os.path.join(model_dir, filename)
    if not os.path.exists(cached_file):
        sys.stderr.write('Downloading: "{}" to {}\n'.format(url, cached_file))
        urlretrieve(url, cached_file)
    return torch.load(cached_file, map_location=map_location)