larry-discuss team mailing list archive

[josef.pktd@xxxxxxxxx]

On Tue, Feb 9, 2010 at 10:23 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Mon, Feb 8, 2010 at 8:42 PM,  <josef.pktd@xxxxxxxxx> wrote:
>> On Mon, Feb 8, 2010 at 11:16 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>> On Mon, Feb 8, 2010 at 7:54 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>>> (back on mailinglist)
>>>>
>>>> On Mon, Feb 8, 2010 at 10:26 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>> On Mon, Feb 8, 2010 at 4:02 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>>>>> I don't have a strong opinion either about the dimension reduction,
>>>>>> for consistency with the numpy philosophy the dimension should be
>>>>>> reduced, for working with larry it is easier for a user to remove than
>>>>>> to add an axis.
>>>>>
>>>>> How about insertaxis for the name? Or do you like addaxis better?
>>>>>
>>>>> insertaxis(axis=0, label=None)
>>>>>
>>>>
>>>> definitely not expand_dims, I had to look at the changes in scipy svn to find it
>>>>
>>>> I usually think of it as addaxis, but I can get used to insertaxis
>>>> (from list analogy)
>>>>
>>>> you can use np.expand_dims to insert axis into x
>>>
>>> Very nice. I didn't know that function existed. (It even handles
>>> negative axes. I should make a unit test to make sure larry methods
>>> can handle negative axes.)
>>>
>>
>> I'm just reading the new lix
>>
>> For this case  lar.lix[['a']:['b']:2]
>>
>> why do you need the list check? you raise a ValueError if it's not a
>> list. this and the fact that slicing start and stop need to be valid
>> labels, seems to indicate that the list is not necessary, i.e.
>> lar.lix['a':'b':2] , and lar.lix['a':'b':2,...]  should be unambiguous
>> for any label type.
>> Do you have an example where this would break? I don't see one right now.
>
> Yes, good point, removing the list requirement for slices should work.
> If, however, we keep the list requirement, then by adding one if
> statement to lix we can also index with integers:
>
> lar.lix[0, ['a', 'b']]

but this  lar.lix[[0,3], ['a', 'b']]  won't work and we get an
inconsistency in what's allowed

> lar.lix[1:[date1]]

this would be useful but not really pretty

> lar.lix[5, [date1]:-1]
>
> That might make it easier to loop:
>
> for i in range(lar.shape[0]):
>    date = datetime.date(2010,1,1) + datetime.timedelta(i)
>    y = lar.lix[i, [date]]

I would prefer this

 for lab in lar.label[0]:
    date = datetime.date(2010,1,1) + datetime.timedelta(i)
    y = lar.lix[lab, date]


>
> And I could even eventually add some tuple support in the form:
>
> lar.lix[([date] - 10):[date]]

I don't think this will work, because python first tries to do  [date]
- 10 and raises an exception
date - 10  or [date-10] would work if date has add and subtract
defined as methods

>
> Yes, I think  that woul be powerful. And the integer support comes for
> free if we keep the list requirement.
>
> What do you think?

I prefer the cleaner/prettier version, although allowing slices that
are integers would be useful

y = lar.lix[5:-2, [date]]
instead of

y = lar.lix[:, [date]][5:-2]
y = lar.lix[:, date1:date2][5:-2]     # does this return view or copy?
if view (which I don't think it does) it would be clean also

or instead of
y = lar.lix[labelatindex(5):labelatindex(-2), date]
where labelatindex(5) is e.g lar.label[0][5]  or whatever is the best
way to get the label from an index

I don't remember
y = lar.lix[:, [date]]

Josef

>
>> I think you can merge if your unit tests pass. Some cosmetic cleaning
>> we could also do in the main branch, e.g. maybe the code duplication
>> is not necessary (unless it's not really duplicate, I'm only reading)
>>
>> Are you ok with merging? There might be a merge conflict with the
>> changelog. I got one each time, I merge your branch.
>>
>> Josef
>>
>