Move tensor to the same gpu of another tensor

Assume I have a multi-GPU system. Let tensor “a” be on one of the GPUs, and tensor “b” be on CPU. How can I move “b” to the same GPU that “a” resides?

Unfortunately, b.type_as(a) always moves b to GPU 0.


1 Like will do exactly that.

Thanks @ptrblck. The problem I have with the “” function is that

  1. If “a” is on GPU and “b” on CPU, then “” does not work (error: …constructor received an invalid combination of arguments…). “” works though, but I am afraid that it is inefficient.

  2. If “a” and “b” are already on the same device, then “” will unnecessarily create a new copy of “b”

I am looking for a function like “b.type_as(a)”, but could automatically move the data to the same device as “a”.

As far as I understand, you would like to move b to the same device as a.
This should work:

a = torch.randn(10, 10).cuda()
b =
c =, 10)
1 Like

@ptrblck The problem is that “b” does not necessarily have the same shape and type of “a”. For example “a” could be 10⨉10 float tensor, while “b” 13⨉19⨉23 int Tensor.

You can pass the standard arguments to new as to a new Tensor:

a = torch.randn(10, 10).cuda()
b =, 19, 23).long()

Would this work?

EDIT: You could of course pass a numpy array or something else to the constructor.
Could you post your use case? I have the feeling, I’m not really understanding your problem and thus posting useless approaches. :wink:


Thanks @ptrblck. I have a huge project, and in most places, in order to move the data to the proper device I used “type_as”. Then I wanted to run several instances of that program on different GPUs of the machine at the same time. The problem was that type_as always uses GPU 0. Right now I am using the approach explained here Select GPU device through env vars, and it solves my problem.

This may be new functionality from the Tensor API, but to move tensor a to the device of tensor b I use:

a =

The following also works irrespective of device:

a =

I think you need to do b = in order to move b to the same GPU that a resides. Otherwise you will do the reverse.