numpy.roll(a, shift, axis=None)
[source]
Roll array elements along a given axis.
Elements that roll beyond the last position are re-introduced at the 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, then axis : int or tuple of ints, optional Axis or axes along which elements are shifted. By default, the array is flattened before shifting, after which the original shape is restored. |
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Returns: |
res : ndarray Output array, with the same shape as |
See also
rollaxis
New in version 1.12.0.
Supports rolling over multiple dimensions simultaneously.
>>> 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)) >>> x2 array([[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]])
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https://docs.scipy.org/doc/numpy-1.12.0/reference/generated/numpy.roll.html