Where is FocalLoss？

[Stellafx]

Thank you for your work! Where is FocalLoss？

[1980x]

Hi. Thanks for your interest. I used CE loss only for implementation. If you wish to use Focal loss, please use below:
import torch
import torch.nn as nn
import torch.nn.functional as F

class FocalLoss(nn.Module):

def __init__(self, weight=None, 
             gamma=2., reduction='none'):
    nn.Module.__init__(self)
    self.weight = weight
    self.gamma = gamma
    self.reduction = reduction
    
def forward(self, input_tensor, target_tensor):
    log_prob = F.log_softmax(input_tensor, dim=-1)
    prob = torch.exp(log_prob)
    return F.nll_loss(
        ((1 - prob) ** self.gamma) * log_prob, 
        target_tensor, 
        weight=self.weight,
        reduction = self.reduction
    )