[Numpy-discussion] Speed performance on array constant set
Mark Heslep
mark at mitre.org
Mon Jan 23 19:21:08 EST 2006
Travis Oliphant wrote:
>> 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.
So that I can step through the array record by record and not field by
field.
>> 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.
Well good to know. Ive been proceeding directly from the NumArray Users
Manual 1.5 by Greenfield/Miller et al that describes the NA High Level
API as the fastest of the APIs available to NA. I thought that NA also
took steps to insure that unnecessary mem copies were not made, unlike
Numeric?
Mark
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