Pytorch expand_as () function

expand()

expand(*sizes)

Tensor will be extended to the same size and parameter sizes.

Parameters:
sizes (torch.Size or int): the need to expand the size. It must be a tuple consisting of ints.

>>> x = torch.Tensor([[1], [2], [3]])
>>> y = x.expand(3, 3)
>>> print(x)
tensor([[1.],
        [2.],
        [3.]])
>>> print(y)
tensor([[1., 1., 1.],
        [2., 2., 2.],
        [3., 3., 3.]])
>>> print(x.shape)
torch.Size([3, 1])
>>> print(y.shape)
torch.Size([3, 3])

expand_as()

expand_as(tensor)

The tensor expanded to the size of the parameters of tensor.

>>> x = torch.randn(1, 3, 1, 1)
>>> y = torch.randn(1, 3, 3, 3)
>>> z = x.expand_as(y)
>>> print(x)
tensor([[[[ 0.4383]],

         [[-1.5909]],

         [[ 0.0814]]]])
>>> print(z)
tensor([[[[ 0.4383,  0.4383,  0.4383],
          [ 0.4383,  0.4383,  0.4383],
          [ 0.4383,  0.4383,  0.4383]],

         [[-1.5909, -1.5909, -1.5909],
          [-1.5909, -1.5909, -1.5909],
          [-1.5909, -1.5909, -1.5909]],

         [[ 0.0814,  0.0814,  0.0814],
          [ 0.0814,  0.0814,  0.0814],
          [ 0.0814,  0.0814,  0.0814]]]])