CODEWITHSUNDEEP
pytorch
abcdaire
abcdaire

Reputation: 1598

Pytorch beginner : tensor.new method

everyone, I have a small question.

What is the purpose of the method tensor.new(..) in Pytorch, I didn't find anything in the documentation. It looks like it creates a new Tensor (like the name suggests), but why we don't just use torch.Tensor constructors instead of using this new method that requires an existing tensor.

Thank you in advance.

Upvotes: 23

Views: 16745

Answers (5)

Yu Yan
Yu Yan

Reputation: 23

The voted answers are right. And I want to add this: I think from the pytorch documentation, we can't actually find the new method explanation. And I guess the reason if that this method is implemented by C, not by python.

Upvotes: 0

devforfu
devforfu

Reputation: 1612

It seems that in the newer versions of PyTorch there are many of various new_* methods that are intended to replace this "legacy" new method.

So if you have some tensor t = torch.randn((3, 4)) then you can construct a new one with the same type and device using one of these methods, depending on your goals:

t = torch.randn((3, 4))
a = t.new_tensor([1, 2, 3])  # same type, device, new data
b = t.new_empty((3, 4))      # same type, device, non-initialized
c = t.new_zeros((2, 3))      # same type, device, filled with zeros
... 

for x in (t, a, b, c):
    print(x.type(), x.device, x.size())
# torch.FloatTensor cpu torch.Size([3, 4])
# torch.FloatTensor cpu torch.Size([3])
# torch.FloatTensor cpu torch.Size([3, 4])
# torch.FloatTensor cpu torch.Size([2, 3])

Upvotes: 11

AruniRC
AruniRC

Reputation: 5148

Here is a simple use-case and example using new(), since without this the utility of this function is not very clear.

Suppose you want to add Gaussian noise to a tensor (or Variable) without knowing a priori what it's datatype is.

This will create a tensor of Gaussian noise, the same shape and data type as a Variable X:

 noise_like_grad = X.data.new(X.size()).normal_(0,0.01)

This example also illustrates the usage of new(size), so that we get a tensor of same type and same size as X.

Upvotes: 6

Wasi Ahmad
Wasi Ahmad

Reputation: 37691

As the documentation of tensor.new() says:

Constructs a new tensor of the same data type as self tensor.

Also note:

For CUDA tensors, this method will create new tensor on the same device as this tensor.

Upvotes: 23

abcdaire
abcdaire

Reputation: 1598

I've found an answer. It is used to create a new tensor with the same type.

Upvotes: 2

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