[Numpy-discussion] Negative indexing.

Benjamin Root ben.root@ou....
Mon Jan 16 15:30:27 CST 2012


On Mon, Jan 16, 2012 at 3:24 PM, Charles R Harris <charlesr.harris@gmail.com
> wrote:

>
>
> On Sat, Jan 14, 2012 at 4:53 PM, Nathan Faggian <nathan.faggian@gmail.com>wrote:
>
>> Hi,
>>
>> I am finding it less than useful to have the negative index wrapping on
>> nd-arrays. Here is a short example:
>>
>> import numpy as np
>> a = np.zeros((3, 3))
>> a[:,2] = 1000
>> print a[0,-1]
>> print a[0,-1]
>> print a[-1,-1]
>>
>> In all cases 1000 is printed out.
>>
>>
> Looks right to me, the whole last column is 1000. What exactly do you want
> to do and what is the problem?
>
> <snip>
>
> Chuck
>
>
I would imagine that it is some sort of image processing use-case, where
sometimes you want the data to reflect at the boundaries, or be constant,
or have some other value used for access outside the domain.  So, for
reflect, I would guess that he would have wanted 0.0 for the first two and
1000 for the last one.

Ben Root
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