[Numpy-discussion] Negative indexing.

Benjamin Root ben.root@ou....
Mon Jan 16 15:42:39 CST 2012


On Mon, Jan 16, 2012 at 3:30 PM, Benjamin Root <ben.root@ou.edu> wrote:

>
>
> 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
>
>
Errr, I mean 0.0 for the last one.  I can't think today.

Ben Root
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