如何解决RuntimeError:3维权重[64,512,1]的3维输入,但尺寸为[4,512]的2维输入
您好,下面是我尝试运行的pytorch模型。但是越来越错误。我也发布了错误跟踪。除非添加卷积层,否则它运行得很好。我对深度学习和Pytorch还是陌生的。因此,我很抱歉这是一个愚蠢的问题。我使用的是conv1d,为什么conv1d为什么要期待3D输入,并且还得到了2d输入,所以也很奇怪。
class Net(nn.Module):
def __init__(self):
super().__init__()
self.fc1 = nn.Linear(CROP_SIZE*CROP_SIZE*3,512)
self.conv1d1 = nn.Conv1d(in_channels=512,out_channels=64,kernel_size=1,stride=2)
self.fc2 = nn.Linear(64,128)
self.conv1d2 = nn.Conv1d(in_channels=128,stride=2)
self.fc3 = nn.Linear(64,256)
self.conv1d3 = nn.Conv1d(in_channels=256,stride=2)
self.fc4 = nn.Linear(64,256)
self.fc4 = nn.Linear(256,128)
self.fc5 = nn.Linear(128,64)
self.fc6 = nn.Linear(64,32)
self.fc7 = nn.Linear(32,64)
self.fc8 = nn.Linear(64,frame['landmark_id'].nunique())
def forward(self,x):
x = F.relu(self.conv1d1(self.fc1(x)))
x = F.relu(self.conv1d2(self.fc2(x)))
x = F.relu(self.conv1d3(self.fc3(x)))
x = F.relu(self.fc4(x))
x = F.relu(self.fc5(x))
x = F.relu(self.fc6(x))
x = F.relu(self.fc7(x))
x = self.fc8(x)
return F.log_softmax(x,dim=1)
net = Net()
import torch.optim as optim
loss_function = nn.CrossEntropyLoss()
net.to(torch.device('cuda:0'))
for epoch in range(3): # 3 full passes over the data
optimizer = optim.Adam(net.parameters(),lr=0.001)
for data in tqdm(train_loader): # `data` is a batch of data
X = data['image'].to(device) # X is the batch of features
y = data['landmarks'].to(device) # y is the batch of targets.
optimizer.zero_grad() # sets gradients to 0 before loss calc. You will do this likely every step.
output = net(X.view(-1,CROP_SIZE*CROP_SIZE*3)) # pass in the reshaped batch
# print(np.argmax(output))
# print(y)
loss = F.nll_loss(output,y) # calc and grab the loss value
loss.backward() # apply this loss backwards thru the network's parameters
optimizer.step() # attempt to optimize weights to account for loss/gradients
print(loss) # print loss. We hope loss (a measure of wrong-ness) declines!
错误跟踪
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
<ipython-input-42-f5ed7999ce57> in <module>
5 y = data['landmarks'].to(device) # y is the batch of targets.
6 optimizer.zero_grad() # sets gradients to 0 before loss calc. You will do this likely every step.
----> 7 output = net(X.view(-1,CROP_SIZE*CROP_SIZE*3)) # pass in the reshaped batch
8 # print(np.argmax(output))
9 # print(y)
/opt/conda/lib/python3.7/site-packages/torch/nn/modules/module.py in __call__(self,*input,**kwargs)
548 result = self._slow_forward(*input,**kwargs)
549 else:
--> 550 result = self.forward(*input,**kwargs)
551 for hook in self._forward_hooks.values():
552 hook_result = hook(self,input,result)
<ipython-input-37-6d3e34d425a0> in forward(self,x)
16
17 def forward(self,x):
---> 18 x = F.relu(self.conv1d1(self.fc1(x)))
19 x = F.relu(self.conv1d2(self.fc2(x)))
20 x = F.relu(self.conv1d3(self.fc3(x)))
/opt/conda/lib/python3.7/site-packages/torch/nn/modules/module.py in __call__(self,result)
/opt/conda/lib/python3.7/site-packages/torch/nn/modules/conv.py in forward(self,input)
210 _single(0),self.dilation,self.groups)
211 return F.conv1d(input,self.weight,self.bias,self.stride,--> 212 self.padding,self.groups)
213
214
RuntimeError: Expected 3-dimensional input for 3-dimensional weight [64,512,1],but got 2-dimensional input of size [4,512] instead
解决方法
您应该了解卷积的工作原理(例如,参见this answer)和一些神经网络基础知识(this tutorial from PyTorch)。
基本上,Conv1d
期望输入形状为[batch,channels,features]
(其中features
可能是一些时间步长,并且可能有所不同,请参见示例)。
nn.Linear
的形状为[batch,features]
,因为它已完全连接并且每个输入要素都已连接到每个输出要素。
对于torch.nn.Linear
,您可以自己验证这些形状:
import torch
layer = torch.nn.Linear(20,10)
data = torch.randn(64,20) # [batch,in_features]
layer(data).shape # [64,10],[batch,out_features]
对于Conv1d
:
layer = torch.nn.Conv1d(in_channels=20,out_channels=10,kernel_size=3,padding=1)
data = torch.randn(64,20,15) # [batch,timesteps]
layer(data).shape # [64,10,15],out_features]
layer(torch.randn(32,25)).shape # [32,25]
顺便说一句。。在处理图像时,应改用torch.nn.Conv
2 d
。
大多数 Pytorch 函数可处理批处理数据,即它们接受大小为(batch_size,shape)
的输入。 @Szymon Maszke已经发布了与此相关的答案。
因此,在您的情况下,可以使用取消挤压和 sqeeze 功能来添加和删除多余的尺寸。
这是示例代码:
import torch
import torch.nn as nn
import torch.nn.functional as F
class Net(nn.Module):
def __init__(self):
super().__init__()
self.fc1 = nn.Linear(100,512)
self.conv1d1 = nn.Conv1d(in_channels=512,out_channels=64,kernel_size=1,stride=2)
self.fc2 = nn.Linear(64,128)
def forward(self,x):
x = self.fc1(x)
x = x.unsqueeze(dim=2)
x = F.relu(self.conv1d1(x))
x = x.squeeze()
x = self.fc2(x)
return x
net = Net()
bsize = 4
inp = torch.randn((bsize,100))
out = net(inp)
print(out.shape)
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