pydsm.relab.shiftdim

pydsm.relab.shiftdim(x, n=None, nargout=2)

Shift dimensions a la Matlab

When n is provided, shiftdim shifts the axes of x by n. If n is positive, it shifts the axes to the left, wrapping the leading axes with non unitary length to the end. When n is negative, it shifts the axes to the right, inserting n leading axes with unitary length. When n is not provided or None, it shifts the axes to the left, reducing the number of dimensions and removing all the leading axes with unitary length.

Parameters

xarray like

multi-dimensional array to operate upon

nint or None, optional

amount to shift. Defaults to None, which means automatic computation

nargoutint

number of output values

Returns

yndarray

the result of the axes shift operation

nint

the actual shift

Examples

>>> from numpy.random import rand
>>> a = rand(1, 1, 3, 1, 2)
>>> b, n = shiftdim(a)
>>> b.shape
(3, 1, 2)
>>> n
2
>>> c = shiftdim(b, -n, nargout=1)
>>> np.alltrue(c == a)
True
>>> d = shiftdim(a, 3, nargout=1)
>>> d.shape
(1, 2, 1, 1, 3)

>>> b, n = shiftdim([[[1]]])
>>> b, n
(array([[[1]]]), 0)