larry-discuss team mailing list archive

[Keith Goodman <kwgoodman@xxxxxxxxx>]

On Mon, Feb 8, 2010 at 10:17 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Mon, Feb 8, 2010 at 10:13 AM,  <josef.pktd@xxxxxxxxx> wrote:
>> On Mon, Feb 8, 2010 at 12:39 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>> Is there a better design? Would it be better to always reorder on
>>> binary operations even if the labels are aligned?
>>
>> I didn't have any good ideas when I briefly looked at the problem. I
>> think my example was when I tried to do a diff() (when I didn't know
>> much about larry yet), but I don't remember any details.
>>
>> For the time axis, ordering is important also for the moving functions
>> and eg. fill_forward.
>> For labels that are names, it would be nice to be able to work with
>> arbitrary ordering.
>>
>> Does _align sort every axis, even if only one axis has disagreement ?
>
> No. Only the axes that are not aligned:
>
>>> y1 = la.larry([[1,2],[3,4]], [[1,0],[0,1]])
>>> y2 = la.larry([[1,2],[3,4]], [[1,0],[1,0]])
>>> y1 + y2
>
> label_0
>    1
>    0
> label_1
>    0
>    1
> x
> array([[3, 3],
>       [7, 7]])

I already ran into a problem with this design:

        lar.lix['a'] # row 'a'
        lar.lix['a':] # row 'a' and everything to the right (slicing)
        lar.lix[:, 'a'] # column 'a'
        lar.lix['a', 'b', 'c'] # single element from 3d larry
        lar.lix[['a', 'b', 'c']] # rows 'a', 'b', and 'c'
        lar.lix['a':'b'] # slice
        lar.lix['a':'b':2] # slice with step

Consider the first example above but instead of 'a', let's make the
label ('a', 2). Inside getitem I won't know what that means. Because:

>> class Index(object):
   ....:     def __init__(self):
   ....:         pass
   ....:     def __getitem__(self, index):
   ....:         print index
   ....:
   ....:
>> idx = Index()
>> idx[('a', 1)]
('a', 1)
>> idx['a', 1]
('a', 1)

So to allow indexing by labels that are tuples, I'll need to change
the design to:

        lar.lix[['a']] # row 'a'
        lar.lix[['a']:] # row 'a' and everything to the right (slicing)
        lar.lix[:, ['a']] # column 'a'
        lar.lix[['a'], ['b'], ['c']] # single element from 3d larry
        lar.lix[['a', 'b', 'c']] # rows 'a', 'b', and 'c'
        lar.lix[['a']:['b']] # slice
        lar.lix[['a']:['b']:2] # slice with step

Not as pretty. I'm starting to wonder if I should push this new
feature to a later release.