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 youshould prefermoveaxis. Themoveaxis function was added in NumPy1.11.

Parameters:

andarray

Input array.

axisint

The axis to be rolled. The positions of the other axes do notchange relative to one another.

startint, optional

Whenstart<=axis, the axis is rolled back until it lies inthis position. Whenstart>axis, the axis is rolled until itlies before this position. The default, 0, results in a “complete”roll. The following table describes how negative values ofstartare interpreted:

start	Normalizedstart
-(arr.ndim+1)	raiseAxisError
-arr.ndim	0
⋮	⋮
-1	arr.ndim-1
0	0
⋮	⋮
arr.ndim	arr.ndim
arr.ndim+1	raiseAxisError

Returns:

resndarray

For NumPy >= 1.10.0 a view ofa is always returned. For earlierNumPy versions a view ofa is returned only if the order of theaxes is changed, otherwise the input array is returned.

See also

moveaxis

Move array axes to new positions.

roll

Roll the elements of an array by a number of positions along a given axis.

Examples

Try it in your browser!

>>>importnumpyasnp>>>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)

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