torch.unflatten — PyTorch 2.7 documentation (original) (raw)

torch.unflatten(input, dim, sizes) → Tensor¶

Expands a dimension of the input tensor over multiple dimensions.

See also

torch.flatten() the inverse of this function. It coalesces several dimensions into one.

Parameters

• input (Tensor) – the input tensor.
• dim (int) – Dimension to be unflattened, specified as an index intoinput.shape.
• sizes (Tuple _[_int]) – New shape of the unflattened dimension. One of its elements can be -1 in which case the corresponding output dimension is inferred. Otherwise, the product of sizes _must_equal input.shape[dim].

Returns

A View of input with the specified dimension unflattened.

Examples::

torch.unflatten(torch.randn(3, 4, 1), 1, (2, 2)).shape torch.Size([3, 2, 2, 1]) torch.unflatten(torch.randn(3, 4, 1), 1, (-1, 2)).shape torch.Size([3, 2, 2, 1]) torch.unflatten(torch.randn(5, 12, 3), -2, (2, 2, 3, 1, 1)).shape torch.Size([5, 2, 2, 3, 1, 1, 3])