Scatter Sub

torch_scatter.scatter_sub(src, index, dim=-1, out=None, dim_size=None, fill_value=0)

Subtracts all values from the src tensor into out at the indices specified in the index tensor along a given axis dim.If multiple indices reference the same location, their negated contributions add (cf. scatter_add()).

For one-dimensional tensors, the operation computes

\[\mathrm{out}_i = \mathrm{out}_i - \sum_j \mathrm{src}_j\]

where \(\sum_j\) is over \(j\) such that \(\mathrm{index}_j = i\).

Parameters:

• src (Tensor) – The source tensor.
• index (LongTensor) – The indices of elements to scatter.
• dim (int, optional) – The axis along which to index. (default: -1)
• out (Tensor, optional) – The destination tensor. (default: None)
• dim_size (int, optional) – If out is not given, automatically create output with size dim_size at dimension dim. If dim_size is not given, a minimal sized output tensor is returned. (default: None)
• fill_value (int, optional) – If out is not given, automatically fill output tensor with fill_value. (default: 0)

Return type:

Tensor

from torch_scatter import scatter_sub

src = torch.Tensor([[2, 0, 1, 4, 3], [0, 2, 1, 3, 4]])
index = torch.tensor([[4, 5, 4, 2, 3], [0, 0, 2, 2, 1]])
out = src.new_zeros((2, 6))

out = scatter_sub(src, index, out=out)

print(out)

tensor([[ 0.,  0., -4., -3., -3.,  0.],
        [-2., -4., -4.,  0.,  0.,  0.]])