2021-10-27

Torch.Tensor

import torch

A = torch.tensor([[[104.0070]],
                  [[116.6688]],
                  [[122.6789]]]) 

#(3,1,1)
print('--------this is the first output')
print(A[:,:,-1])

'''
tensor([[104.0070],
        [116.6688],
        [122.6789]])
'''
print('--------this is the second output')

print(A[:,:,:-1])

'''
tensor([], size=(3, 1, 0))
'''
#A[:,:,::-1]  BUG::::  ValueError: negative step not yet supported

B = torch.tensor([[104.0070],
                  [116.6688],
                  [122.6789]])
#namely, B=A[:,:,-1]
print(B[:,-1]) #tensor([104.0070, 116.6688, 122.6789])


a = [1,2,3,4]
print(a[:-1])
#[1, 2, 3]
print(a[::-1])
#[4, 3, 2, 1]