Input type (torch.FloatTensor) and weight type (torch.cuda.FloatTensor) should be the same

Question

****I set my model and data to the same device, but always raise the error like this: RuntimeError: Input type (torch.FloatTensor) and weight type (torch.cuda.FloatTensor) should be the same** The following is training code**

total_epoch = 1   
best_epoch = 0
training_losses = []
val_losses = []

for epoch in range(total_epoch):

    epoch_train_loss = 0

    for X, y in train_loader:

    X, y = X.cuda(), y.cuda()

    optimizer.zero_grad()
    result = model(X)
    loss = criterion(result, y).
    epoch_train_loss += loss.item()
    loss.backward()
    optimizer.step()

training_losses.append(epoch_train_loss)


epoch_val_loss = 0
correct = 0
total = 0

with torch.no_grad():
    for X, y in val_loader:

        X, y = X.cuda(), y.cuda()

        result = model(X)
        loss = criterion(result, y)
        epoch_val_loss += loss.item()
        _, maximum = torch.max(result.data, 1)
        total += y.size(0)
        correct += (maximum == y).sum().item()

val_losses.append(epoch_val_loss)
accuracy = correct/total
print("EPOCH:", epoch, ", Training Loss:", epoch_train_loss, ", Validation Loss:", epoch_val_loss, ", Accuracy: ", accuracy)


if min(val_losses) == val_losses[-1]:
    best_epoch = epoch
    checkpoint = {'model': model,
                        'state_dict': model.state_dict(),
                        'optimizer' : optimizer.state_dict()}

    torch.save(checkpoint, models_dir + '{}.pth'.format(epoch))
    print("Model saved")

when i Run the following code for detection using cv2.capture(0) .

import cvlib as cv
from PIL import Image

cap = cv2.VideoCapture(0)

font_scale=1
thickness = 2
red = (0,0,255)
green = (0,255,0)
blue = (255,0,0)
font=cv2.FONT_HERSHEY_SIMPLEX

face_cascade = cv2.CascadeClassifier( cv2.data.haarcascades +'haarcascade_frontalface_default.xml')

while(cap.isOpened()):
    ret, frame = cap.read()
    if ret == True:

    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray, 1.4, 4)

    for (x, y, w, h) in faces:

        cv2.rectangle(frame, (x, y), (x+w, y+h), blue, 2)

        croped_img = frame[y:y+h, x:x+w]
        pil_image = Image.fromarray(croped_img, mode = "RGB")
        pil_image = train_transforms(pil_image)
        image = pil_image.unsqueeze(0)


        result = loaded_model(image)
        _, maximum = torch.max(result.data, 1)
        prediction = maximum.item()


        if prediction == 0:
            cv2.putText(frame, "Masked", (x,y - 10), font, font_scale, green, thickness)
            cv2.rectangle(frame, (x, y), (x+w, y+h), green, 2)
        elif prediction == 1:
            cv2.putText(frame, "No Mask", (x,y - 10), font, font_scale, red, thickness)
            cv2.rectangle(frame, (x, y), (x+w, y+h), red, 2)

    cv2.imshow('frame',frame)

    if (cv2.waitKey(1) & 0xFF) == ord('q'):
        break
else:
    break

cap.release() cv2.destroyAllWindows()

about the function loaded_model declared as below

def load_checkpoint(filepath):
checkpoint = torch.load(filepath)
model = checkpoint['model']
model.load_state_dict(checkpoint['state_dict'])
for parameter in model.parameters():
parameter.requires_grad = False



return model.eval()


filepath = models_dir + str(best_epoch) + ".pth"
loaded_model = load_checkpoint(filepath)

ERROR:

---------------------------------------------------------------------------

RuntimeError                              Traceback (most recent call last)

<ipython-input-29-b3a630684f44> in <module>()
     43 
     44 
---> 45             result = loaded_model(image)
     46             _, maximum = torch.max(result.data, 1)
     47             prediction = maximum.item()

5 frames

/usr/local/lib/python3.6/dist-packages/torch/nn/modules/conv.py in _conv_forward(self, input, weight)
    344                             _pair(0), self.dilation, self.groups)
    345         return F.conv2d(input, weight, self.bias, self.stride,
--> 346                         self.padding, self.dilation, self.groups)
    347 
    348     def forward(self, input):

RuntimeError: Input type (torch.FloatTensor) and weight type (torch.cuda.FloatTensor) should be the same

**I hope you can answer it.Thanks!**

Answer 1

The model's weights are on the GPU, while the image is on the CPU. You need to put it onto the GPU as well.

image = pil_image.unsqueeze(0)
image = image.cuda()

result = loaded_model(image)

It looks like you didn't manually put the model onto the GPU, but rather that you saved the model's weights, which were originally on the GPU, and PyTorch keeps the device information when saving the state dict. If you want to run the model on the CPU, you should make sure that the weights are on the CPU. torch.load accepts a map_location argument, which forces the loaded data to be on the specified device, rather than using the saved device.

# Load weights onto the CPU regardless of saved device.
checkpoint = torch.load(filepath, map_location="cpu")