[FIXED] How to remove an element from the torch tensor list?

Issue

I have torch tensor list that looks like below

tensor([[[-1.8510e-01,  1.3181e-01,  3.2903e-01,  ...,  1.9867e-01,
           5.1037e-03,  6.4071e-03],
         [-4.6331e-01,  2.0216e-01,  2.7916e-01,  ...,  2.6695e-01,
          -1.3543e-02,  5.3604e-02],
         [-3.8719e-01,  2.9603e-01,  2.5516e-01,  ...,  1.7509e-01,
           8.9148e-02,  3.7516e-02],

and the shape of this torch tensor is [500, 197, 768]

There are 500 images with 197*768 dimensions. I need to remove the instance of some images. Lets say if I remove 5 images then the shape will be [495, 197, 768] Can anyone tell me how to remove this using index?

Solution

It depends on where along that dimension you want to remove the items.

To remove the first/last n elements (using normal Python indexing):

new_data = data[n:] # Remove first n elements
new_data = data[:-n] # Remove last n elements

To remove n items inside the tensor, you will need to specify a start-index s (s+n should not be larger than the length along that dimension):

new_data = torch.cat((data[:s], data[s+n:]), dim=0) # Remove n elements starting at s

To remove using a list of indices you could do the following:

indices = [6, 7, 9, 100, 204] # Arbitrary list of indices that should be removed
indices_to_keep = [i for i in range(data.shape[0]) if i not in indices] # List of indices that should be kept
new_data = data[torch.LongTensor(indices_to_keep)]

Answered By - willdalh