# mars.tensor.roll¶

mars.tensor.roll(a, shift, axis=None)[source]

Roll tensor elements along a given axis.

Elements that roll beyond the last position are re-introduced at the first.

Parameters
• a (array_like) – Input tensor.

• shift (int or tuple of ints) – The number of places by which elements are shifted. If a tuple, then axis must be a tuple of the same size, and each of the given axes is shifted by the corresponding number. If an int while axis is a tuple of ints, then the same value is used for all given axes.

• axis (int or tuple of ints, optional) – Axis or axes along which elements are shifted. By default, the tensor is flattened before shifting, after which the original shape is restored.

Returns

res – Output tensor, with the same shape as a.

Return type

Tensor

`rollaxis`

Roll the specified axis backwards, until it lies in a given position.

Notes

Supports rolling over multiple dimensions simultaneously.

Examples

```>>> import mars.tensor as mt
```
```>>> x = mt.arange(10)
>>> mt.roll(x, 2).execute()
array([8, 9, 0, 1, 2, 3, 4, 5, 6, 7])
```
```>>> x2 = mt.reshape(x, (2,5))
>>> x2.execute()
array([[0, 1, 2, 3, 4],
[5, 6, 7, 8, 9]])
>>> mt.roll(x2, 1).execute()
array([[9, 0, 1, 2, 3],
[4, 5, 6, 7, 8]])
>>> mt.roll(x2, 1, axis=0).execute()
array([[5, 6, 7, 8, 9],
[0, 1, 2, 3, 4]])
>>> mt.roll(x2, 1, axis=1).execute()
array([[4, 0, 1, 2, 3],
[9, 5, 6, 7, 8]])
```