Initial commit

models/Old/efficientnet.py

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+'''EfficientNet in PyTorch.
+
+Paper: "EfficientNet: Rethinking Model Scaling for Convolutional Neural Networks".
+
+Reference: https://github.com/keras-team/keras-applications/blob/master/keras_applications/efficientnet.py
+'''
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+def swish(x):
+    return x * x.sigmoid()
+
+
+def drop_connect(x, drop_ratio):
+    keep_ratio = 1.0 - drop_ratio
+    mask = torch.empty([x.shape[0], 1, 1, 1], dtype=x.dtype, device=x.device)
+    mask.bernoulli_(keep_ratio)
+    x.div_(keep_ratio)
+    x.mul_(mask)
+    return x
+
+
+class SE(nn.Module):
+    '''Squeeze-and-Excitation block with Swish.'''
+
+    def __init__(self, in_channels, se_channels):
+        super(SE, self).__init__()
+        self.se1 = nn.Conv2d(in_channels, se_channels,
+                             kernel_size=1, bias=True)
+        self.se2 = nn.Conv2d(se_channels, in_channels,
+                             kernel_size=1, bias=True)
+
+    def forward(self, x):
+        out = F.adaptive_avg_pool2d(x, (1, 1))
+        out = swish(self.se1(out))
+        out = self.se2(out).sigmoid()
+        out = x * out
+        return out
+
+
+class Block(nn.Module):
+    '''expansion + depthwise + pointwise + squeeze-excitation'''
+
+    def __init__(self,
+                 in_channels,
+                 out_channels,
+                 kernel_size,
+                 stride,
+                 expand_ratio=1,
+                 se_ratio=0.,
+                 drop_rate=0.):
+        super(Block, self).__init__()
+        self.stride = stride
+        self.drop_rate = drop_rate
+        self.expand_ratio = expand_ratio
+
+        # Expansion
+        channels = expand_ratio * in_channels
+        self.conv1 = nn.Conv2d(in_channels,
+                               channels,
+                               kernel_size=1,
+                               stride=1,
+                               padding=0,
+                               bias=False)
+        self.bn1 = nn.BatchNorm2d(channels)
+
+        # Depthwise conv
+        self.conv2 = nn.Conv2d(channels,
+                               channels,
+                               kernel_size=kernel_size,
+                               stride=stride,
+                               padding=(1 if kernel_size == 3 else 2),
+                               groups=channels,
+                               bias=False)
+        self.bn2 = nn.BatchNorm2d(channels)
+
+        # SE layers
+        se_channels = int(in_channels * se_ratio)
+        self.se = SE(channels, se_channels)
+
+        # Output
+        self.conv3 = nn.Conv2d(channels,
+                               out_channels,
+                               kernel_size=1,
+                               stride=1,
+                               padding=0,
+                               bias=False)
+        self.bn3 = nn.BatchNorm2d(out_channels)
+
+        # Skip connection if in and out shapes are the same (MV-V2 style)
+        self.has_skip = (stride == 1) and (in_channels == out_channels)
+
+    def forward(self, x):
+        out = x if self.expand_ratio == 1 else swish(self.bn1(self.conv1(x)))
+        out = swish(self.bn2(self.conv2(out)))
+        out = self.se(out)
+        out = self.bn3(self.conv3(out))
+        if self.has_skip:
+            if self.training and self.drop_rate > 0:
+                out = drop_connect(out, self.drop_rate)
+            out = out + x
+        return out
+
+
+class EfficientNet(nn.Module):
+    def __init__(self, cfg, num_classes=10):
+        super(EfficientNet, self).__init__()
+        self.cfg = cfg
+        self.conv1 = nn.Conv2d(3,
+                               32,
+                               kernel_size=3,
+                               stride=1,
+                               padding=1,
+                               bias=False)
+        self.bn1 = nn.BatchNorm2d(32)
+        self.layers = self._make_layers(in_channels=32)
+        self.linear = nn.Linear(cfg['out_channels'][-1], num_classes)
+
+    def _make_layers(self, in_channels):
+        layers = []
+        cfg = [self.cfg[k] for k in ['expansion', 'out_channels', 'num_blocks', 'kernel_size',
+                                     'stride']]
+        b = 0
+        blocks = sum(self.cfg['num_blocks'])
+        for expansion, out_channels, num_blocks, kernel_size, stride in zip(*cfg):
+            strides = [stride] + [1] * (num_blocks - 1)
+            for stride in strides:
+                drop_rate = self.cfg['drop_connect_rate'] * b / blocks
+                layers.append(
+                    Block(in_channels,
+                          out_channels,
+                          kernel_size,
+                          stride,
+                          expansion,
+                          se_ratio=0.25,
+                          drop_rate=drop_rate))
+                in_channels = out_channels
+        return nn.Sequential(*layers)
+
+    def forward(self, x):
+        out = swish(self.bn1(self.conv1(x)))
+        out = self.layers(out)
+        out = F.adaptive_avg_pool2d(out, 1)
+        out = out.view(out.size(0), -1)
+        dropout_rate = self.cfg['dropout_rate']
+        if self.training and dropout_rate > 0:
+            out = F.dropout(out, p=dropout_rate)
+        out = self.linear(out)
+        return out
+
+
+def EfficientNetB0():
+    cfg = {
+        'num_blocks': [1, 2, 2, 3, 3, 4, 1],
+        'expansion': [1, 6, 6, 6, 6, 6, 6],
+        'out_channels': [16, 24, 40, 80, 112, 192, 320],
+        'kernel_size': [3, 3, 5, 3, 5, 5, 3],
+        'stride': [1, 2, 2, 2, 1, 2, 1],
+        'dropout_rate': 0.2,
+        'drop_connect_rate': 0.2,
+    }
+    return EfficientNet(cfg)
+
+
+def test():
+    net = EfficientNetB0()
+    x = torch.randn(2, 3, 32, 32)
+    y = net(x)
+    print(y.shape)
+
+
+if __name__ == '__main__':
+    test()