Pytorch-损失函数-NLLLoss

class torch.nn.NLLLoss(weight=None, size_average=None, ignore_index=-100,

reduce=None, reduction=‘mean‘)

import torch

import torch.nn as nn

import torch.nn.functional as F

torch.manual_seed(2019)
output = torch.randn(1, 3) # 网络输出

target = torch.ones(1, dtype=torch.long).random_(3) # 真实标签

print(output)

print(target)
# 直接调用

loss = F.nll_loss(output, target)

print(loss)
# 实例化类

criterion = nn.NLLLoss()

loss = criterion(output, target)

print(loss)
"""

tensor([[-0.1187, 0.2110, 0.7463]])

tensor([1])

tensor(-0.2110)

tensor(-0.2110)

"""

import torch

import torch.nn as nn

import torch.nn.functional as F

torch.manual_seed(2019)
output = torch.randn(2, 3) # 网路输出

target = torch.ones(2, dtype=torch.long).random_(3) # 真实标签

print(output)

print(target)
# 直接调用

loss = F.nll_loss(output, target)

print(loss)
# 实例化类

criterion = nn.NLLLoss(reduction=‘none‘)

loss = criterion(output, target)

print(loss)
"""

tensor([[-0.1187, 0.2110, 0.7463],

[-0.6136, -0.1186, 1.5565]])

tensor([2, 0])

tensor(-0.0664)

tensor([-0.7463, 0.6136])

"""