[Numpy-discussion] using the same vocabulary for missing value ideas

[Benjamin Root]

On Wednesday, July 6, 2011, Dag Sverre Seljebotn
<d.s.seljebotn at astro.uio.no> wrote:
> On 07/06/2011 08:25 PM, Christopher Barker wrote:
>> Mark Wiebe wrote:
>>> 1) NA vs IGNORE and bitpattern vs mask are completely independent. Any
>>> combination of NA as bitpattern, NA as mask, IGNORE as bitpattern, and
>>> IGNORE as mask are reasonable.
>>
>> Is this really true? if you use a bitpattern for IGNORE, haven't you
>> just lost the ability to get the original value back if you want to stop
>> ignoring it? Maybe that's not inherent to what an IGNORE means, but it
>> seems pretty key to me.
>
> There's the question of how reductions treats the value. IIUC, IGNORE as
> bitpattern would imply that reductions treat the value as 0, which is a
> question orthogonal to whether the value can possibly be unmasked or not.
>
> Dag Sverre
>

Just because we are trying to be exact here, the reductions would
treat IGNORE as the operation's identity.  Therefore, for addition, it
would be treated like 0, but for multiplication, it is treated like a
1.

Ben Root