# tensorplay.functional.argwhere

Source: https://www.tensorplay.cn/docs/generated/tensorplay.functional.argwhere.html

```python
tensorplay.functional.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 = tensorplay.tensor([1, 0, 1])
>>> tensorplay.argwhere(t)
tensor([[0],
        [2]])
>>> t = tensorplay.tensor([[1, 0, 1], [0, 1, 1]])
>>> tensorplay.argwhere(t)
tensor([[0, 0],
        [0, 2],
        [1, 1],
        [1, 2]])
```