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path: root/simclr/models.py
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import torch
from torch import nn, Tensor
from torchvision.models import ResNet
from torchvision.models.resnet import BasicBlock


# TODO Make a SimCLR base class

class CIFARSimCLRResNet50(ResNet):
    def __init__(self, hid_dim, out_dim):
        super(CIFARSimCLRResNet50, self).__init__(
            block=BasicBlock, layers=[3, 4, 6, 3], num_classes=hid_dim
        )
        self.conv1 = nn.Conv2d(3, 64, kernel_size=3,
                               stride=1, padding=1, bias=False)
        self.projector = nn.Sequential(
            nn.Linear(hid_dim, hid_dim),
            nn.ReLU(inplace=True),
            nn.Linear(hid_dim, out_dim),
        )

    def backbone(self, x: Tensor) -> Tensor:
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)

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

        x = self.avgpool(x)
        x = torch.flatten(x, 1)
        x = self.fc(x)

        return x

    def forward(self, x: Tensor) -> Tensor:
        h = self.backbone(x)
        z = self.projector(h)
        return z


class ImageNetSimCLRResNet50(ResNet):
    def __init__(self, hid_dim, out_dim):
        super(ImageNetSimCLRResNet50, self).__init__(
            block=BasicBlock, layers=[3, 4, 6, 3], num_classes=hid_dim
        )
        self.projector = nn.Sequential(
            nn.Linear(hid_dim, hid_dim),
            nn.ReLU(inplace=True),
            nn.Linear(hid_dim, out_dim),
        )

    def forward(self, x: Tensor) -> Tensor:
        h = super(ImageNetSimCLRResNet50, self).forward(x)
        z = self.projector(h)
        return z