larry-discuss team mailing list archive

[josef.pktd@xxxxxxxxx]

On Mon, Feb 8, 2010 at 11:54 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Mon, Feb 8, 2010 at 7:31 AM,  <josef.pktd@xxxxxxxxx> wrote:
>> On Mon, Feb 8, 2010 at 10:18 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>> On Mon, Feb 8, 2010 at 7:15 AM,  <josef.pktd@xxxxxxxxx> wrote:
>>>> On Mon, Feb 8, 2010 at 10:05 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>> After a long thread on how to support label indexing in larry, here's
>>>>> where we ended up:
>>>>>
>>>>> 1. Remove the indexing of labels by strings from the trunk.
>>>>>
>>>>> 2. Create a method larry.lix that can be used for label indexing like this:
>>>>>
>>>>> lar.lix['a']
>>>>> lar.lix['a':]
>>>>> lar.lix[:, 'a']
>>>>> lar.lix['a', 'b', 'c':]
>>>>
>>>> I'm not sure what the last index means, if there are several labels
>>>> for the same axis, they would need to be in a list_like
>>>> lar.lix[['a', 'b', 'c'], :]   to distinguish different elements for
>>>> one axis from elements for several axis.
>>>
>>> Yep. Good catch. Typo.
>>
>> just for clarification, you also want to support label slices?
>>
>> lar.lix[['a', 'b', 'c'], '2009-01-01':]  or
>> lar.lix[['a', 'b', 'c'], date1 :date2]
>>
>> I don't think there is any ambiguity in the interpretation
>
> Yes, slices will be supported. So both of your examples will work if
> the corresponding labels exists. Looking at your date slice made be
> realize that larry needs a sortlabel method
>
> def sortlabel(axis=None):
>    etc.
>
> where axis=None will sort all axes.

When I started initially to work with some examples I found the label
ordering a bit confusing. I think any call to _align returns a larry
with sorted labels. Initially I had a descending sorted larry and
after some binary operations, I had a ascending sorted larry.

There is currently no guarantee of preserving label ordering unless
it's ascending sort order, is there?
I'm not sure what the policy is, and I don't think that there are any
unit tests that would check label ordering.

Josef

>
>>
>>>>
>>>> Josef
>>>>
>>>>>
>>>>> Only labels and slices are allowed. Inside the function the labels
>>>>> will be converted to indices and then a call will be made to
>>>>> lar[converted_index].
>>>>>
>>>>> 3. Indexing with more than one list will do rectangular indexing, not
>>>>> fancy indexing.
>>>>>
>>>>> OK, that's it. I'll start. I'll need help with #3
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>
>>>
>>
>