larry-discuss team mailing list archive

[Keith Goodman <kwgoodman@xxxxxxxxx>]

On Sun, Feb 7, 2010 at 7:53 PM,  <josef.pktd@xxxxxxxxx> wrote:
> On Sun, Feb 7, 2010 at 10:43 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>> On Sun, Feb 7, 2010 at 7:40 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>> On Sun, Feb 7, 2010 at 10:23 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>> On Sun, Feb 7, 2010 at 7:11 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>>>
>>>>> If you want to go this way, you could have lixs :  lix with strings,
>>>>> and lixr : lix with repr , ... ?
>>>>> lix would be safe  because it uses the labels directly, the other ones
>>>>> are only recommended in restricted cases where the string (or other)
>>>>> representation makes sense.
>>>>
>>>> Too confusing with two I think.
>>>>
>>>>> if you want to allow slicing i.e. `:`  then I think lix would need to
>>>>> use its __getitem__ instead of __call__ or __init__
>>>>> lar1[1:4, lix['msft', google], lixs['2010-02-01':]   or lar1[1:4,
>>>>> lix[['msft', google]], lixs['2010-02-01':] ?
>>>>
>>>> lar1[lix(date)]: will work. So will lar[lix(date1):lix(date2)]
>>>>
>>>> Allowing slices slows things down because now we have to look instead
>>>> each slice object (slice.start, slice.stop) for lix object and if
>>>> found convert them.
>>>
>>> I wouldn't mix lix and regular array slices or indices for the same
>>> axis. I would restrict it to if either one of (slice.start,
>>> slice.stop) are lix then both are interpreted as labels.
>>>
>>> either lar[lix[date1:date2],:]   or   lar[lix(date1):lix(date2), :]
>>> but not lar[lix(date1):-3]
>>
>> How come? Seems handy to me.
>
> Just a feeling, mixing oranges and apples, (If I have one label, I
> expect also to have the other, or I have neither in the other case)
>
> It would be useful to write a babyclass with the different versions of
> getitem. It's easier to see what's going on and to experiment than
> using the already more complicated getitem of larry.
>
> Josef
>
>>
>>
>>>
>>>>
>>>>> I don't know if lix should hold some code for conversion from label
>>>>> representation to indices, or be just an identifier for use in
>>>>> larry.__getitem__
>>>>
>>>> Yeah, a method getindex that takes label as input, perhaps. larry's
>>>> getitem is already getting harry, so keeping the code in lix instead
>>>> of adding yet more code to getitem might be a good idea. Or make a
>>>> function in util.misc like a did for string indexing.

I'm thinking of allowing only one label element in lix. But allow
mixing label and integers for slicing.

I tried allowing multiple labels per axis in the first indexing by
labels blueprint. It's hard. So as a first step, only allow one. For
example:

lar[lix(date1):lix(date2)]
lar[:lix(date2)]
lar[lix(date1):-1]