[AstroPy] Linearity correction by polynomial fitting

Joe Philip Ninan indiajoe@gmail....
Thu Apr 18 14:00:11 CDT 2013


Hi James,
I think i shall try to keep the code as much pure python as possible.
Installing iraf on the controller machine just for one routine will
probably be an over kill.
Nadia sent me link to pull request of astropy which can do fitting on 2d
array. So i only have to flatten by 3d to a 2d, with time along the column.
( https://github.com/astropy/astropy/pull/493 ).
This isn't merged to astropy yet, but i was told it will be merged soon.
Thanks for the suggestions,
-cheers
joe


On 18 April 2013 22:49, James Turner <jturner@gemini.edu> wrote:

> > But I couldn't find anything for fitting a polynomial for every pixel
> along an
> > axis of an ndarray.
> > Is there a tool to do this? Without implementing a python loop to loop
> through
> > each pixel and calculate coefficients?
>
> I'm not sure if there is anything yet (could tell you how to do
> it in IRAF), as I think fitting has been a bit of a missing area
> in Python until some recent work-in-progress. But wouldn't it
> help to use Cython? I was also wondering whether a Python loop
> will really be that slow if you're doing something relatively
> non-trivial like a fit, but it probably will be since the axis
> you're fitting will be much shorter than the image size...
>
> Cheers,
>
> James.
>
>
> > Worst case scenario, i think i will have to write a C routine to do
> polynomial
> > fit and call it from python. But i would really love if a pure python
> > alternative exists.
> >
> > Thanks
> > -cheers
> > joe
> >
> >
> >
> >
> >
> > --
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> > TIFR,                           | Pullad P.O.         |
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-- 
/---------------------------------------------------------------
"GNU/Linux: because a PC is a terrible thing to waste" -  GNU Generation

************************************************
Joe Philip Ninan    http://sites.google.com/site/jpninan/
Research Scholar        /________________\
DAA,                            | Vadakeparambil |
TIFR,                           | Pullad P.O.         |
Mumbai-05, India.      | Kerala, India      |
Ph: +917738438212   | PIN:689548       |
------------------------------\_______________/--------------
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