[Numpy-discussion] Numeric vs numarray?
oliphant at ee.byu.edu
Thu Feb 10 01:27:00 EST 2005
Timo Korvola wrote:
>Andrew McNamara <andrewm at object-craft.com.au> writes:
>>I know this is a loaded question, but what does numarray offer that
>>Numeric does not (as they stand today)? A cleaner implementation?
>NA_OutputArray and NA_IoArray. Very convenient for wrapping C
>libraries. NA_InputArray is more or less equivalent to
>PyArray_ContiguousFromObject but as far as I know Numeric has nothing
>equivalent to the other two.
I am not convinced these are really useful additional C-API calls. I've
done a fair bit of wrapping of C libraries and have never needed
This idea of "shadowing" ala NA_IOArray is a new one. Can somebody show
me an example of it's usefulness that could not be handled by simply a
PyArray_ContiguousFromObject with an explicit copy back at the end? I
don't like this idea of "hiding" what is going on from the user.
This kind of C-API alteration which as far as I can tell has not been
well justified is an example of some of the problems I see with Numarray.
Numeric3 condenses the Numeric API calls using numarray's idea of the
PyArray_FromAny(PyObject *op, PyArray_Typecode *typecode, int mindepth,
int maxdepth, int requires)
typecode is a simple structure with integer elements (type_num,
itemsize, and fortran).
For some unexplained reason, the mindepth and maxdepth arguments are not
copied by the new Numarray C-API. I'm not sure why. Having them does
make it easier to guarantee you are getting the right dimension for the
array you want rather than having to check after the fact.
These kinds of discussions about numarray's C-API never took place. In
my opinion the Numeric C-API is better tested and easier to understand.
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