[AstroPy] Missing some statistical method for your astronomy analyses in Python?

Jerome Caron jerome_caron_astro@ymail....
Tue Jan 15 03:51:53 CST 2013


Dear Christoph
I think the calculation of median values in Numpy is not optimal. I don't know if there are other libraries that do better?
On my machine I get these results:
>>> data = numpy.random.rand(5000,5000)
>>> t0=time.time();print numpy.ma.median(data);print time.time()-t0
0.499845739822
15.1949999332
>>> t0=time.time();print numpy.median(data);print time.time()-t0
0.499845739822
4.32100009918
>>> t0=time.time();print aspylib.astro.get_median(data);print time.time()-t0
[ 0.49984574]
0.90499997139
>>>

The median calculation in Aspylib is using C code from Nicolas Devillard (can be found here: http://ndevilla.free.fr/median/index.html) interfaced with ctypes.
It could be easily re-used for other, more official packages. I think the code also finds quantiles efficiently.
Kind regards
Jerome Caron
  

________________________________
 De : Christoph Deil <deil.christoph@googlemail.com>
À : "astropy@scipy.org list" <astropy@scipy.org> 
Envoyé le : Mardi 15 janvier 2013 8h42
Objet : [AstroPy] Missing some statistical method for your astronomy analyses in Python?
  

Dear all, 

we would like to know which statistical methods you want to use for you astronomy work with Python that are not readily available e.g. in scipy or one of the existing scientific Python packages like e.g. statsmodels, scikit-learn, astroML, …

Please visit the wiki page for what has already been suggested, then reply to this email or make an addition to the https://github.com/astropy/astropy/wiki/What-methods-do-we-want-in-astropy.stats?  wiki page directly.

The plan is to add these methods either to astropy.stats or, if they are not astronomy-specific, to one of the existing scientific Python packages.

Christoph

PS: This discussion started as a thread on astropy-dev ( https://groups.google.com/d/topic/astropy-dev/Zwgafam171E/discussion ), but it was suggested to also ask here.
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