numpy.rollaxis#
- numpy.rollaxis(a, axis, start=0)[source]#
Roll the specified axis backwards, until it lies in a given position.
This function continues to be supported for backward compatibility, but you should prefer
moveaxis
. Themoveaxis
function was added in NumPy 1.11.- Parameters
- andarray
Input array.
- axisint
The axis to be rolled. The positions of the other axes do not change relative to one another.
- startint, optional
When
start <= axis
, the axis is rolled back until it lies in this position. Whenstart > axis
, the axis is rolled until it lies before this position. The default, 0, results in a “complete” roll. The following table describes how negative values ofstart
are interpreted:start
Normalized
start
-(arr.ndim+1)
raise
AxisError
-arr.ndim
0
⋮
⋮
-1
arr.ndim-1
0
0
⋮
⋮
arr.ndim
arr.ndim
arr.ndim + 1
raise
AxisError
- Returns
- resndarray
For NumPy >= 1.10.0 a view of a is always returned. For earlier NumPy versions a view of a is returned only if the order of the axes is changed, otherwise the input array is returned.
See also
Examples
>>> a = np.ones((3,4,5,6)) >>> np.rollaxis(a, 3, 1).shape (3, 6, 4, 5) >>> np.rollaxis(a, 2).shape (5, 3, 4, 6) >>> np.rollaxis(a, 1, 4).shape (3, 5, 6, 4)