Replace all nonzero values by zero and all zero values by a specific value
I have a 3d tensor which contains some zero and nonzero values. I want to replace all nonzero values by zero and zero values by a specific value. How can I do that?



Pretty much exactly how you would do it using numpy, like so:

tensor[tensor!=0] = 0


In order to replace zeros and non-zeros, you can just chain them together. Just be sure to use a copy of the tensor, since they get modified:

def custom_replace(tensor, on_zero, on_non_zero):
    # we create a copy of the original tensor, 
    # because of the way we are replacing them.
    res = tensor.clone()
    res[tensor==0] = on_zero
    res[tensor!=0] = on_non_zero
    return res


And use it like so:

&gt;&gt;&gt;z 
(0 ,.,.) = 
  0  1
  1  3

(1 ,.,.) = 
  0  1
  1  0
[torch.LongTensor of size 2x2x2]

&gt;&gt;&gt;out = custom_replace(z, on_zero=5, on_non_zero=0)
&gt;&gt;&gt;out
(0 ,.,.) = 
  5  0
  0  0

(1 ,.,.) = 
  5  0
  0  5
[torch.LongTensor of size 2x2x2]

