torch.argwhere

torch.argwhere(input) → Tensor

Returns a tensor containing the indices of all non-zero elements of input. Each row in the result contains the indices of a non-zero element in input. The result is sorted lexicographically, with the last index changing the fastest (C-style).

If input has $n$ dimensions, then the resulting indices tensor out is of size $(z \times n)$, where $z$ is the total number of non-zero elements in the input tensor.

Note

This function is similar to NumPy’s argwhere.

When input is on CUDA, this function causes host-device synchronization.

Parameters

{input} –

Example:

>>> t = torch.tensor([1, 0, 1])
>>> torch.argwhere(t)
tensor([[0],
        [2]])
>>> t = torch.tensor([[1, 0, 1], [0, 1, 1]])
>>> torch.argwhere(t)
tensor([[0, 0],
        [0, 2],
        [1, 1],
        [1, 2]])