focal_loss.py 文件源码

def forward(self, output, target):

        cross_entropy = F.cross_entropy(output, target)
        cross_entropy_log = torch.log(cross_entropy)

        focal_loss = -((1 - cross_entropy) ** self.focusing_param) * cross_entropy_log

        balanced_focal_loss = self.balance_param * focal_loss

        return balanced_focal_loss