Hi Jacob,
For example, in _gradient_boosting.pyx (in //sklearn/ensemble/) the
function _predict_regression_tree_inplace_fast has the first parameter of
type np.float32_t* . When this function is called from predict_stages, the
first argument is X.data , where X is a numpy.ndarray. The reason this
works is that cython knows that the underlying C object that is used for
numpy.ndarray's has a field "data" of type char* that points to the raw
data buffer of the numpy array.
What I am planning to do is as follows. The current signature of the
function is
_predict_regression_tree_inplace_fast(np.float32_t* X , ...)
If this can be changed to
_predict_regression_tree_inplace_fast(np.float32 [:,:] X, ... )
then this generalizes to use any object X that exposes the buffer protocol
(described by PEP 3118 of python). Thoughts on whether this is something
useful for the scikit community? I am probably going to make this change in
my local branch, anyway. I can push these changes back to scikit if there
is interest.
Thanks,
Mahesh
On Wed, Feb 10, 2016 at 8:15 PM, Jacob Vanderplas <jake...@cs.washington.edu
> wrote:
> Hi Mahesh,
> Regarding the raw data access, what specific parts of the code are you
> looking at?
> Thanks,
> Jake
>
> Jake VanderPlas
> Senior Data Science Fellow
> Director of Research in Physical Sciences
> University of Washington eScience Institute
>
> On Wed, Feb 10, 2016 at 6:09 PM, mahesh ravishankar <
> mahesh.ravishan...@gmail.com> wrote:
>
>> Hi,
>>
>> I am looking at scikit as an app for prototyping a Python module that
>> exposes an array-like object I am developing. I was going through the
>> Cython files and see that a lot of places, the raw data buffer of numpy are
>> accessed by accessing the c-field (i.e. "data" field) exposed through the
>> cython/numpy interface. I am a relative newbie to cython, but from my
>> understanding using typed memoryview (
>> http://docs.cython.org/src/userguide/memoryviews.html#memoryview-objects-and-cython-arrays)
>> is the recommended way of accessing data in an array object. I was
>> wondering if this was done due to legacy reasons, or performance reasons?
>>
>> For me to evaluate my array object interface, I am thinking of changing
>> scikit to use the typed memoryview. If there is interest in this, I can
>> push this change to scikit. Any comments about why this would not be a good
>> idea are deeply appreciated.
>>
>> Thanks,
>> --
>> Mahesh
>>
>>
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--
Mahesh
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