[Numpy-discussion] Speed performance on array constant set

Travis Oliphant oliphant at ee.byu.edu
Mon Jan 23 16:37:05 CST 2006


Mark Heslep wrote:

> Christopher Barker wrote:
>
>> Mark Heslep wrote:
>>
>>> Ive got some NumArray C API investment in the typemaps.
>>
>>
>>
>> Are these SWIG typemaps? If so I think there are a bunch of us that 
>> wold like to see them, and maybe we can all work together to port 
>> them to NumPy.
>>
>> -Chris
>>
> Yes they are SWIG typemaps for OpenCv* data structures, based on prior 
> Numeric art I'd found and ported to Numarray.
> Attached.
>
> 1. numdata.h  example that works well for simple Cv structures  
> containing uniform types:  CvPoint2D32F  => struct { float x, float y 
> }.  Can I use a record array here, or is there some Numpy overhead 
> interlaced with fields?

You can use a record array, but for uniform types I don't know what the 
advantage is (except for perhaps named-field slicing---which may 
actually be faster I'm not sure) over a x2 float array. 

> 2. numarray.h  Attempt to replace the main Cv Image structures CvMat, 
> IplImage.  Needs work. Some success but there's segfault or two in 
> there somewhere.
>
These can be ported fairly easily, I think (actually, the old Numeric 
typemaps would still work --- and work with Numarray), so the basic 
Numeric C-API still presents itself as the simplest way to support all 
the array packages.

-Travis





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