[Numpy-discussion] yet another indexing question
Chris.Barker
Chris.Barker at noaa.gov
Mon Oct 17 13:13:32 EDT 2011
On 10/14/11 5:04 AM, Neal Becker wrote:
> suppose I have:
>
> In [10]: u
> Out[10]:
> array([[0, 1, 2, 3, 4],
> [5, 6, 7, 8, 9]])
>
> And I have a vector v:
> v = np.array ((0,1,0,1,0))
>
> I want to form an output vector which selects items from u where v is the index
> of the row of u to be selected.
> Now, more importantly, I need the result to be a reference to the original array
> (not a copy), because I'm going to use it on the LHS of an assignment. Is this
> possible?
No, it's not. numpy arrays need to be describable with regular strides
-- when selecting arbitrary elements from an array, there is no way to
describe the resulting array as regular strides into the same data block
as the original.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker at noaa.gov
More information about the NumPy-Discussion
mailing list