How to apply residual links to simple FFNN

I want to apply the residual link used in ResNet to a simple model. Can I just add the input x and the output value passed through the linear layer in the element-wise direction as shown below?
Is there anything else I need to do more?

class neuralNet(torch.nn.Module):

    def __init__(self, input_size, hidden_size, num_classes):
        super(neuralNet, self).__init__()
        self.linear1 = torch.nn.Linear(input_size, hidden_size)
        self.relu1 = nn.ReLU()
        self.linear2 = torch.nn.Linear(hidden_size, hidden_size)
        self.relu2 = nn.ReLU()

        self.linear3 = torch.nn.Linear(hidden_size, hidden_size)
        self.relu3 = nn.ReLU()
        self.linear4 = torch.nn.Linear(hidden_size, output_size)
        self.relu4 = nn.ReLU()

    def forward(self, x):
        out = self.linear1(x)
        out = self.relu1(out)
        out = self.linear2(out)
        out = out.add(x)            # H(x) = F(x) + x
        out = self.relu2(out)

        out = self.linear3(out)
        out = self.relu3(out)
        out = self.linear4(out)
        out = out.add(x)            # H(x) = F(x) + x
        out = self.relu4(out)

        return out

Your approach should work and the torchvision implementation of ResNet uses a similar approach as seen here.

1 Like

Thank you always for good answers every time. It was very helpful.