how to solve dimension mismatch error for CNN on images in pyTorch?

问题

I have input data (colored images) in the shape of (100, 64, 64, 3) and tried to train a CNN with 2 conv/pooling layers on it for binary classification. I keep encountering size mismatch error. Also attempted reshape the images into (-1, 3, 64, 64) size

class SimpleCNN(nn.Module):

    def __init__(self, input_dim, hidden_dim, output_dim, kernel_size):
        super(SimpleCNN, self).__init__()

        self.conv1 = nn.Conv2d(3, 10, kernel_size, padding=0)
        self.conv2 = nn.Conv2d(10, 20, kernel_size, padding=0)
        self.fc1 = nn.Linear(hidden_dim*16*16, hidden_dim)
        self.fc2 = nn.Linear(output_dim, output_dim)

    def forward(self, x):
        x = F.max_pool2d((self.conv1(x)), 2)
        x = F.max_pool2d(F.relu(self.conv2(x)), 2)
        x = F.relu(self.fc1(x))
        x = F.relu(self.fc2(x))
        return F.softmax(x)

net = SimpleCNN(in_channels, hidden_dim, out_channels, kernel_size)

criterion = nn.CrossEntropyLoss()
optimizer = torch.optim.Adam(net.parameters(), lr=learning_rate)

losses = []
idx = []
count=1
for epoch in range(num_epochs):
    for i, (images, labels) in enumerate(train_loader):
        images = Variable(images.view(-1, 3, n_pixel, n_pixel))
        labels = Variable(labels)

        # Intialize the hidden weight to all zeros
        optimizer.zero_grad()
        # Forward pass: compute the output class given a image
        outputs = net(images)
        # Compute the loss: difference between the output class and the pre-given label
        loss = criterion(outputs, labels)
        # Backward pass: compute the weight
        loss.backward()
        # Optimizer: update the weights of hidden nodes
        optimizer.step()
        count+=1

        if (i+1) % 10 == 0:
            idx.append(count)
            losses.append(loss.data.numpy().tolist())

The full error msg is

only batches of spatial targets supported (3D tensors) but got targets of dimension: 1 at /pytorch/aten/src/THNN/generic/SpatialClassNLLCriterion.c:61'

来源：https://stackoverflow.com/questions/58325886/how-to-solve-dimension-mismatch-error-for-cnn-on-images-in-pytorch

标签

python

conv-neural-network

pytorch