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27 lines
816 B
27 lines
816 B
6 years ago
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import torch.nn as nn
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import torch.nn.functional as F
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class LabelSmoothingCrossEntropy(nn.Module):
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"""
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NLL loss with label smoothing.
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"""
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def __init__(self, smoothing=0.1):
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"""
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Constructor for the LabelSmoothing module.
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:param smoothing: label smoothing factor
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"""
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super(LabelSmoothingCrossEntropy, self).__init__()
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assert smoothing < 1.0
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self.smoothing = smoothing
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self.confidence = 1. - smoothing
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def forward(self, x, target):
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logprobs = F.log_softmax(x, dim=-1)
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nll_loss = -logprobs.gather(dim=-1, index=target.unsqueeze(1))
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nll_loss = nll_loss.squeeze(1)
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smooth_loss = -logprobs.mean(dim=-1)
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loss = self.confidence * nll_loss + self.smoothing * smooth_loss
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return loss.mean()
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