# Axis swap¶

New in version 5.0.0.

Change the order and sign of 2,3 or 4 axes.

Alias |
axisswap |

Domain |
2D, 3D or 4D |

Input type |
Any |

Output type |
Any |

Each of the possible four axes are numbered with 1–4, such that the first input axis is 1, the second is 2 and so on. The output ordering is controlled by a list of the input axes re-ordered to the new mapping.

## Usage¶

Reversing the order of the axes:

```
+proj=axisswap +order=4,3,2,1
```

Swapping the first two axes (x and y):

```
+proj=axisswap +order=2,1,3,4
```

The direction, or sign, of an axis can be changed by adding a minus in front of the axis-number:

```
+proj=axisswap +order=1,-2,3,4
```

It is only necessary to specify the axes that are affected by the swap operation:

```
+proj=axisswap +order=2,1
```