numpy.roll¶

numpy.roll(a,shift,axis=None)[source]¶

Roll array elements along a given axis.

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

Parameters:

a : array_like Input array. shift : int or tuple of ints The number of places by which elements are shifted. If a tuple,thenaxis must be a tuple of the same size, and each of thegiven axes is shifted by the corresponding number. If an intwhileaxis is a tuple of ints, then the same value is used forall given axes. axis : int or tuple of ints, optional Axis or axes along which elements are shifted. By default, thearray is flattened before shifting, after which the originalshape is restored.

Returns:

res : ndarray Output array, with the same shape asa.

See also

rollaxis

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

Notes

New in version 1.12.0.

Supports rolling over multiple dimensions simultaneously.

Examples

>>>x=np.arange(10)>>>np.roll(x,2)array([8, 9, 0, 1, 2, 3, 4, 5, 6, 7])

>>>x2=np.reshape(x,(2,5))>>>x2array([[0, 1, 2, 3, 4],       [5, 6, 7, 8, 9]])>>>np.roll(x2,1)array([[9, 0, 1, 2, 3],       [4, 5, 6, 7, 8]])>>>np.roll(x2,1,axis=0)array([[5, 6, 7, 8, 9],       [0, 1, 2, 3, 4]])>>>np.roll(x2,1,axis=1)array([[4, 0, 1, 2, 3],       [9, 5, 6, 7, 8]])