# tensorplay.nn.utils.rnn.invert_permutation

Source: https://www.tensorplay.cn/docs/generated/tensorplay.nn.utils.rnn.invert_permutation.html

```python
tensorplay.nn.utils.rnn.invert_permutation(permutation: Tensor | None) → Tensor | None
```

Returns the inverse of permutation.

This is useful for converting between sorted and unsorted indices in
a PackedSequence.

Parameters:

permutation ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor), optional) – a 1-D tensor of indices to invert