# Image classification tensor

Hello @ptrblck,

In fact, i want to concat image pixels (train_x) and their labels(train_y). Then I want to convert to tensor.
I don’t know how to do ?

Thank You

Some more details about your objective might help.

In order to concat 2 tensors, they need to be the same size, except in the dim being concatenated. You could do:

``````labels = torch.empty_like(train_x)
labels[:, 0, labels.size()[1], :] = train_y.view(-1, 1, labels.size()[1], 1)

data_labels=torch.cat([train_x, labels], dim=1)
``````

But, in most cases, you might find it easier to just use:

``````data_labels = [train_x, train_y]
...
train_x, train_y = data_labels[0], data_labels[1]
``````

Thank you so much ! I will try it

But i have an error =

Call `view` on a PyTorch tensor not a numpy array:

``````x = torch.randn(2, 3, 4, 5)
x = x.view(-1, 1, 1, 1) # works

x = np.random.randn(2, 3, 4, 5)
x = x.view(-1, 1, 1, 1) # fails
# TypeError: view() takes from 0 to 2 positional arguments but 4 were given
``````
1 Like

As @ptrblck said, if it’s a NumPy object, you’ll need to convert it into a Pytorch tensor, via `torch.from_numpy()`:

``````labels[:, 0, labels.size()[1], :] = torch.from_numpy(train_y).view(-1, 1, labels.size()[1], 1)

data_labels=torch.cat([train_x, labels], dim=1)
``````

https://pytorch.org/docs/stable/generated/torch.from_numpy.html

I have an error :

You changed `train_y.view(-1,1,labels.size()[1], 1)` to `train_y.view(-1,1,labels.size()[0], 1)`. The `-1` is intended to capture the batch size, as this can be variable, while the labels.size()[1] captures the number of labels per item. Change it back to dim 1 so the sizes match.

Additionally, it seems your images are removing a dim. Images should have 4 dimensions: batch size, channels, height, width.

If you are getting your images/labels from a numpy dataloader, it could be squeezing the channels dim. You’ll need that back in to pass to a model for inference, if it has convolutional layers. i.e. `train_x=train_x.unsqueeze(1)`

If the model is strictly linear layers, then you can resize the labels view accordingly.

But in train_x there are pixels for each images.

I changed because i got this error :

As I suspected, you’re missing the channels dim. Does your model have Conv2D layers?

I did not train the model. In fact, for the image classification, i have a folder with human faces and two csv files : train_csv contains the name of image (ex : 0001.jpg) and the label (1 or -1). So i start to collect then into datframe.

Then just remove the 2nd dim in the .view():

``````labels[:,0: labels.size()[1], 0:1] = train_y.view(-1, labels.size()[1], 1)
``````

It did not change:

Can you print the sizes of `train_x` and `train_y`?

Yes :

``````import torch

train_x=torch.rand(200, 130, 130)
train_y=torch.rand(200)

labels = torch.empty_like(train_x)
labels[:,:1, :1] = train_y.view(-1, 1, 1)

data_labels=torch.cat([train_x, labels], dim=1)

print(data_labels.size())
``````