[Numpy-discussion] BOF notes: Fernando's proposal: NumPy ndarray with named axes

Joshua Holbrook josh.holbrook@gmail....
Fri Jul 9 19:52:04 CDT 2010


On Fri, Jul 9, 2010 at 4:22 PM, Keith Goodman <kwgoodman@gmail.com> wrote:
> On Fri, Jul 9, 2010 at 5:00 PM, Christopher Barker
> <Chris.Barker@noaa.gov> wrote:
>> Keith Goodman wrote:
>>> On Fri, Jul 9, 2010 at 4:05 PM, Christopher Barker
>>> <Chris.Barker@noaa.gov> wrote:
>>>
>>>> So what would you get if you wanted:
>>>>
>>>> MyDataArray['jones':'wilson']
>>>>
>>>> or
>>>>
>>>> MyDataArray.names[slice('jones','wilson')]
>>>>
>>>> or whatever the syntax would be?
>>>>
>>>> If it was in alphabetical order, you'd be all set, but what it if
>>>> wasn't? It would be pretty cool if you could get an alphabetical slice.
>>>
>>> If it sorted the data automatically then you couldn't turn off the
>>> sorting.
>>
>> sure -- but what would it mean to ask for a slice by name without
>> sorting? If you want it in the order it happens to be in, you'd use
>> numerical slicing (at least that's the use case I can imagine).
>
> That is true. It would just save you from having to look up the index value.
>
> Another handy method would take tick and axis as input and return the index:
> http://larry.sourceforge.net/reference.html#la.larry.labelindex
>
>>> Without automatic sorting the user gets to decide whether or
>>> not to sort before indexing. A sort ticks along axis function would be
>>> useful, sort of like
>>> http://larry.sourceforge.net/reference.html#la.larry.sortaxis.
>>
>> Yup -- that's nice, and would take care of most issues.
>>
>> -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@noaa.gov
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Idea: What if we specified axes/ticks like this (using a 2-d example I
made up for myself):

punnet=DataArray([[1,2],[2,4]], {'row': ['a','A'], 'column': ['a','A']})

That is, use a dictionary instead of nested tuples or separate lists?

--Josh


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