larry-discuss team mailing list archive

[Keith Goodman <kwgoodman@xxxxxxxxx>]

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.