padding zeroes to a tensor on both dimensions
I have a tensor t

1 2
3 4
5 6
7 8


And I would like to make it 

0 0 0 0
0 1 2 0
0 3 4 0
0 5 6 0
0 7 8 0
0 0 0 0 


I tried stacking with new=torch.tensor([0. 0. 0. 0.]) tensor four times but that did not work. 

t = torch.arange(8).reshape(1,4,2).float()
print(t)
new=torch.tensor([[0., 0., 0.,0.]])
print(new)
r = torch.stack([t,new])  # invalid argument 0: Tensors must have same number of dimensions: got 4 and 3
new=torch.tensor([[[0., 0., 0.,0.]]])
print(new)
r = torch.stack([t,new])  # invalid argument 0: Sizes of tensors must match except in dimension 0.


I also tried cat, that did not work either.

It is probably better to initialize an array of the desired shape first, and then add the data at the appropriate indices.

import torch

t = torch.arange(8).reshape(1,4,2).float()
x = torch.zeros((1, t.shape[1]+2, t.shape[2]+2))
x[:, 1:-1, 1:-1] = t

print(x)


On the other hand, if you just want to pad your tensor with zeroes (and not just add extra zeroes somewhere), you can use torch.nn.functional.pad:

import torch

t = torch.arange(8).reshape(1, 4, 2).float()
x = torch.nn.functional.pad(t, (1, 1, 1, 1))

print(x)

