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383bfb8 | 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 | import torch
import torch.nn as nn
import math
def init_layer(L):
# Initialization using fan-in
if isinstance(L, nn.Conv2d):
n = L.kernel_size[0]*L.kernel_size[1]*L.out_channels
L.weight.data.normal_(0,math.sqrt(2.0/float(n)))
elif isinstance(L, nn.BatchNorm2d):
L.weight.data.fill_(1)
L.bias.data.fill_(0)
class Flatten(nn.Module):
def __init__(self):
super(Flatten, self).__init__()
def forward(self, x):
return x.view(x.size(0), -1)
# Simple ResNet Block
class SimpleBlock(nn.Module):
maml = False #Default
def __init__(self, indim, outdim, half_res):
super(SimpleBlock, self).__init__()
self.indim = indim
self.outdim = outdim
self.C1 = nn.Conv2d(indim, outdim, kernel_size=3, stride=2 if half_res else 1, padding=1, bias=False)
self.BN1 = nn.BatchNorm2d(outdim)
self.C2 = nn.Conv2d(outdim, outdim,kernel_size=3, padding=1,bias=False)
self.BN2 = nn.BatchNorm2d(outdim)
self.relu1 = nn.ReLU(inplace=True)
self.relu2 = nn.ReLU(inplace=True)
self.parametrized_layers = [self.C1, self.C2, self.BN1, self.BN2]
self.half_res = half_res
# if the input number of channels is not equal to the output, then need a 1x1 convolution
if indim!=outdim:
self.shortcut = nn.Conv2d(indim, outdim, 1, 2 if half_res else 1, bias=False)
self.BNshortcut = nn.BatchNorm2d(outdim)
self.parametrized_layers.append(self.shortcut)
self.parametrized_layers.append(self.BNshortcut)
self.shortcut_type = '1x1'
else:
self.shortcut_type = 'identity'
for layer in self.parametrized_layers:
init_layer(layer)
def forward(self, x):
out = self.C1(x)
out = self.BN1(out)
out = self.relu1(out)
out = self.C2(out)
out = self.BN2(out)
short_out = x if self.shortcut_type == 'identity' else self.BNshortcut(self.shortcut(x))
out = out + short_out
out = self.relu2(out)
return out
# Bottleneck block
class BottleneckBlock(nn.Module):
maml = False #Default
def __init__(self, indim, outdim, half_res):
super(BottleneckBlock, self).__init__()
bottleneckdim = int(outdim/4)
self.indim = indim
self.outdim = outdim
self.C1 = nn.Conv2d(indim, bottleneckdim, kernel_size=1, bias=False)
self.BN1 = nn.BatchNorm2d(bottleneckdim)
self.C2 = nn.Conv2d(bottleneckdim, bottleneckdim, kernel_size=3, stride=2 if half_res else 1,padding=1)
self.BN2 = nn.BatchNorm2d(bottleneckdim)
self.C3 = nn.Conv2d(bottleneckdim, outdim, kernel_size=1, bias=False)
self.BN3 = nn.BatchNorm2d(outdim)
self.relu = nn.ReLU()
self.parametrized_layers = [self.C1, self.BN1, self.C2, self.BN2, self.C3, self.BN3]
self.half_res = half_res
# if the input number of channels is not equal to the output, then need a 1x1 convolution
if indim!=outdim:
self.shortcut = nn.Conv2d(indim, outdim, 1, stride=2 if half_res else 1, bias=False)
self.parametrized_layers.append(self.shortcut)
self.shortcut_type = '1x1'
else:
self.shortcut_type = 'identity'
for layer in self.parametrized_layers:
init_layer(layer)
def forward(self, x):
short_out = x if self.shortcut_type == 'identity' else self.shortcut(x)
out = self.C1(x)
out = self.BN1(out)
out = self.relu(out)
out = self.C2(out)
out = self.BN2(out)
out = self.relu(out)
out = self.C3(out)
out = self.BN3(out)
out = out + short_out
out = self.relu(out)
return out
class ResNet(nn.Module):
maml = False #Default
def __init__(self,block,list_of_num_layers, list_of_out_dims, flatten = True):
# list_of_num_layers specifies number of layers in each stage
# list_of_out_dims specifies number of output channel for each stage
super(ResNet,self).__init__()
assert len(list_of_num_layers)==4, 'Can have only four stages'
conv1 = nn.Conv2d(3, 64, kernel_size=7, stride=2, padding=3,
bias=False)
bn1 = nn.BatchNorm2d(64)
relu = nn.ReLU()
pool1 = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
init_layer(conv1)
init_layer(bn1)
trunk = [conv1, bn1, relu, pool1]
indim = 64
for i in range(4):
for j in range(list_of_num_layers[i]):
half_res = (i>=1) and (j==0)
B = block(indim, list_of_out_dims[i], half_res)
trunk.append(B)
indim = list_of_out_dims[i]
if flatten:
avgpool = nn.AvgPool2d(4)
trunk.append(avgpool)
trunk.append(Flatten())
self.final_feat_dim = indim
else:
self.final_feat_dim = [indim, 4, 4]
self.trunk = nn.Sequential(*trunk)
def forward(self,x):
out = self.trunk(x)
return out
def ResNet10(flatten = True):
return ResNet(SimpleBlock, [1,1,1,1],[64,128,256,512], flatten)
def ResNet18(flatten = True):
return ResNet(SimpleBlock, [2,2,2,2],[64,128,256,512], flatten)
def ResNet34(flatten = True):
return ResNet(SimpleBlock, [3,4,6,3],[64,128,256,512], flatten)
def ResNet50(flatten = True):
return ResNet(BottleneckBlock, [3,4,6,3], [256,512,1024,2048], flatten)
def ResNet101(flatten = True):
return ResNet(BottleneckBlock, [3,4,23,3],[256,512,1024,2048], flatten)
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