larry-discuss team mailing list archive

[josef.pktd@xxxxxxxxx]

On Mon, Feb 8, 2010 at 4:19 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Mon, Feb 8, 2010 at 1:02 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>> On Mon, Feb 8, 2010 at 12:59 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>> On Mon, Feb 8, 2010 at 3:51 PM,  <josef.pktd@xxxxxxxxx> wrote:
>>>> On Mon, Feb 8, 2010 at 3:37 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>> On Mon, Feb 8, 2010 at 12:27 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>>> I made a branch called index-by-label:
>>>>>>
>>>>>> https://code.launchpad.net/~kwgoodman/larry/index-by-label
>>>>>>
>>>>>> and added support for indexing by label. It is all self contained in
>>>>>> one method: deflarry.py(lix). So easy to try.
>>>>>>
>>>>>> Here are a few one-off tests:
>>>>>>
>>>>>>>> y = la.larry([[1,2],[3,4]], [['a', 'b'], ['c', 'd']])
>>>>>>
>>>>>>>> y.lix[['a']]
>>>>>> label_0
>>>>>>    c
>>>>>>    d
>>>>>> x
>>>>>> array([1, 2])
>>>>>>
>>>>>>>> y.lix[['b', 'a']]
>>>>>> label_0
>>>>>>    b
>>>>>>    a
>>>>>> label_1
>>>>>>    c
>>>>>>    d
>>>>>> x
>>>>>> array([[3, 4],
>>>>>>       [1, 2]])
>>>>>>
>>>>>>>> y.lix[['a']:]
>>>>>> label_0
>>>>>>    a
>>>>>>    b
>>>>>> label_1
>>>>>>    c
>>>>>>    d
>>>>>> x
>>>>>> array([[1, 2],
>>>>>>       [3, 4]])
>>>>>>
>>>>>>>> y.lix[:['b']]
>>>>>> label_0
>>>>>>    a
>>>>>> label_1
>>>>>>    c
>>>>>>    d
>>>>>> x
>>>>>> array([[1, 2]])
>>>>>>
>>>>>>>> y.lix[['a'], ['c']:]
>>>>>> label_0
>>>>>>    c
>>>>>>    d
>>>>>> x
>>>>>> array([1, 2])
>>>>>>
>>>>>>>> y.lix[['a'], ['d', 'c']]
>>>>>> label_0
>>>>>>    d
>>>>>>    c
>>>>>> x
>>>>>> array([2, 1])
>>>>>>
>>>>>>>> y.lix['a':]  # <--- expected to crash
>>>>>> ValueError: The start element of a slice must be a list.
>>>>>
>>>>> I think the only thing left to add is the conversion of fancy indexing
>>>>> to rectangular:
>>>>>
>>>>>>> y.lix[['a', 'b'], ['d', 'c']]
>>>>> IndexError: tuple index out of range
>>>>>
>>>>> How do I identify rectangular indexing? If more than one list with
>>>>> more than one element are present anywhere in the index, then it is
>>>>> rectangular and I need to do your trick np.array(first list)[:,None]?
>>>>
>>>> that's the idea, with matching axes added
>>>>
>>>> can you use np.idx_ directly, once you have the numeric index list ?
>>>>
>>>> y.x[np.ix_(lists of indices)]
>>>>
>>>> might not work with slices, to avoid problems with mixing slices and
>>>> array indexing, I converted slices in the past to a array of indices
>>>>
>>>> slice(None)   -> np.arange(x.shape(ax))
>>>
>>> actually, I looked this up in the numpy thread with David Huard on
>>> indexing/slicing
>>>
>>>>>> range(*slice(None).indices(5))
>>> [0, 1, 2, 3, 4]
>>>>>> range(*slice(2,None,None).indices(5))
>>> [2, 3, 4]
>>>>>> range(*slice(None,2,None).indices(5))
>>> [0, 1]
>>
>> Very nice!
>
> The np.ix_ conversion is working:
>
>>> y = la.larry([[1,2],[3,4]], [['a', 'b'], ['c', 'd']])
>>> y.lix[['a', 'b'], ['d', 'c']]
>
> The index (['a', 'b'], ['d', 'c']) is converted to
>
> (array([[0],
>       [1]]), array([[1, 0]]))
>
> So the lix method is done. The only problem left is that
> larry.__getitem__ does not support that type of indexing.

I thought my earlier example with broadcasting worked.

you could also return a new sliced larry directly in lix instead of
going through getitem.
you already have the index array for the array lar1.x[...]
all you need to add, is the loop on selecting labels, for with you
also have already the list of lists of indices, so it should be a
short loop.

Josef