我在pytorch“RuntimeError:invalid argument 2:size'[1 x 400]上收到此错误”

Question

有谁能帮我纠正这个错误吗？

RuntimeError: invalid argument 2: size '[-1 x 400]' is invalid for input of with 1597248 elements at /Users/soumith/miniconda2/conda-bld/pytorch_1503975723910/work/torch/lib/TH/THStorage.c:37

class Net(nn.Module):
    def __init__(self):
        super(Net, self).__init__()
        self.conv1 = nn.Conv2d(3, 6, 5)
        self.pool = nn.MaxPool2d(2, 2)
        self.conv2 = nn.Conv2d(6, 16, 5)
        self.fc1 = nn.Linear(16 * 5 * 5, 120)
        self.fc2 = nn.Linear(120, 84)
        self.fc3 = nn.Linear(84, 10)

    def forward(self, x):
        x = self.pool(F.relu(self.conv1(x)))
        x = self.pool(F.relu(self.conv2(x)))
        x = x.view(-1, 16 * 5 * 5)
        x = F.relu(self.fc1(x))
        x = F.relu(self.fc2(x))
        x = self.fc3(x)
        return x


net = Net()

import torch.optim as optim

criterion = nn.CrossEntropyLoss()
optimizer = optim.SGD(net.parameters(), lr=0.001, momentum=0.9)
for epoch in range(2):  # loop over the dataset multiple times

    running_loss = 0.0
    for i, data in enumerate(trainloader, 0):
        # get the inputs
        inputs, labels = data

        # wrap them in Variable
        inputs, labels = Variable(inputs), Variable(labels)

        # zero the parameter gradients
        optimizer.zero_grad()

        # forward + backward + optimize
        outputs = net(inputs)
        loss = criterion(outputs, labels)
        loss.backward()
        optimizer.step()

        # print statistics
        running_loss += loss.data[0]
        if i % 5 == 4:    # print every 2000 mini-batches
            print('[%d, %5d] loss: %.3f' %
                  (epoch + 1, i + 1, running_loss / 5))
            running_loss = 0.0

print('Finished Training')

Answer 1

你的问题是图像的大小不是32*32。 要解决这个问题，需要根据网络的输入大小计算self.fc1的输入大小。

Answer 2

计算输入大小应该可以在不缩放图像的情况下解决它。 公式是 输出大小=（图像大小+2*填充-过滤器）/跨距+1）

Answer 3

当我缩放图像大小时，错误停止发生。

transform = transforms.Compose(
                   [transforms.Scale((32,32)),
                    transforms.ToTensor(),
                    transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])