larry-discuss team mailing list archive

[josef.pktd@xxxxxxxxx]

On Sun, Feb 7, 2010 at 11:08 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Sun, Feb 7, 2010 at 8:06 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>> 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]
>
> BTW, all this can already be done of course:
>
> lar[lar.labelindex(date1,0):lar.labelindex(date2,0)]
> lar[:lar.labelindex(date2,0)]
> lar[lar.labelindex(date1,0):-1]

the usecase I had initially in mind was a list of labels
lar1[:, ['msft', 'google', 'f2', 'f3'], ['open', 'close']].diff(3).log().diff(0)

labelindex allows only single label

Josef