Slices time complexity

[Fabien]

On 05/18/2015 09:49 PM, Ian Kelly wrote:
> It may be possible that lists in CPython could be made to share their
> internal arrays with other lists on a copy-on-write basis, which could
> allow slicing to be O(1) as long as neither list is modified while the
> array is being shared. I expect this would be a substantial piece of
> work, and I don't know if it's something that anybody has looked into.

Isn't Numpy doing this (not sure, not a python nor a numpy expert):

 >>> import numpy as np
 >>> a = np.array([1,2,3,4])
 >>> b = a[1:]
 >>> b[0] = 9
 >>> a
array([1, 9, 3, 4])


Fabien