做二进制类分类。我使用二元交叉熵作为损失函数(nn.BCEloss()),最后一层的单位是一。
在我将(输入,目标)放入损失函数之前,我将目标从Long转换为浮动。只有DataLoader的最后一步出现错误消息,错误消息如下所示。
"RuntimeError: Expected object of scalar type Float but got scalar type Long for argument #2 'target'"
DataLoader(如果批量大小不匹配,我丢弃最后一批)在代码中定义,我不确定是否与错误有关联。
我试图打印目标和输入的类型(神经网络的输出),并且两个变量的类型都是浮点数。我把“类型结果”和代码放在下面。
trainloader = torch.utils.data.DataLoader(trainset, batch_size=BATCH_SIZE,
shuffle=True, drop_last=True)
loss_func = nn.BCELoss()
# training
for epoch in range(EPOCH):
test_loss = 0
train_loss = 0
for step, (b_x, b_y) in enumerate(trainloader): # gives batch data
b_x = b_x.view(-1, TIME_STEP, 1) # reshape x to (batch, time_step, input_size)
print("step: ", step)
b_x = b_x.to(device)
print("BEFORE|b_y type: ",b_y.type())
b_y = b_y.to(device, dtype=torch.float)
print("AFTER|b_y type: ",b_y.type())
output = rnn(b_x) # rnn output
print("output type:", output.type())
loss = loss_func(output, b_y) # !!!error occurs when trainloader enumerate the final step!!!
train_loss = train_loss + loss
optimizer.zero_grad()
loss.backward()
optimizer.step()
#### type result and the error message####
...
step: 6
BEFORE|b_y type: torch.LongTensor
AFTER|b_y type: torch.cuda.FloatTensor
output type: torch.cuda.FloatTensor
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
<ipython-input-18-e028fcb6b840> in <module>
30 b_y = b_y.to(device)
31 output = rnn(b_x)
---> 32 loss = loss_func(output, b_y)
33 test_loss = test_loss + loss
34 rnn.train()
~/venvs/tf1.12/lib/python3.5/site-packages/torch/nn/modules/module.py in __call__(self, *input, **kwargs)
487 result = self._slow_forward(*input, **kwargs)
488 else:
--> 489 result = self.forward(*input, **kwargs)
490 for hook in self._forward_hooks.values():
491 hook_result = hook(self, input, result)
~/venvs/tf1.12/lib/python3.5/site-packages/torch/nn/modules/loss.py in forward(self, input, target)
502 @weak_script_method
503 def forward(self, input, target):
--> 504 return F.binary_cross_entropy(input, target, weight=self.weight, reduction=self.reduction)
505
506
~/venvs/tf1.12/lib/python3.5/site-packages/torch/nn/functional.py in binary_cross_entropy(input, target, weight, size_average, reduce, reduction)
2025
2026 return torch._C._nn.binary_cross_entropy(
-> 2027 input, target, weight, reduction_enum)
2028
2029
RuntimeError: Expected object of scalar type Float but got scalar type Long for argument #2 'target'
似乎正确地更改了类型,因为您声明在打印类型时从Pyyerch观察到更改:
返回带有指定设备的
Tensor
和(可选)dtype
。如果dtype为None,则推断为self.dtype
。当non_blocking
尝试尽可能地相对于主机进行异步转换时,例如,将带有固定内存的CPU Tensor转换为CUDA Tensor。设置复制后,即使Tensor已匹配所需的转换,也会创建新的Tensor。
和其他方法一样
b_y = b_y.to(device).float()
不应该有显着差异,因为.float()
相当于.to(..., torch.float32)
。和.float
相当于.float32
。你可以在抛出错误之前验证b_y
的类型并编辑问题吗? (我本来是一个评论 - 但我想添加更多细节。我会尽力提供帮助)