[AstroPy] using astropy.coordinates.angular_separation()

[Richard Moffat]

I just want to mirror what John said about converting 2.7 to 3.x. It may be
a lot simpler than you think.

My last two companies have converted thousands of files. Python 2.7 is dead
and it is exponentially more difficult to keep as time goes on.

*Noho ora mai,*
*All the best,*
Richard Moffat.

==============================================================

richard.moffat at gmail.com
==============================================================






On Fri, 11 Aug 2023 at 05:33, John Parejko <parejkoj at uw.edu> wrote:

> There are tools to help automatically transition code from 2 to 3. python2
> is no longer supported, and no major projects are producing or updating
> libraries for python2, so you're just making your own life much more
> difficult. A few thousand lines of code should be quite easy to do: LSST
> transitioned about 300,000 lines of code in early 2018.
>
> https://community.lsst.org/t/python-2-no-longer-supported/2845/2
>
> Here is the official transition tool that will take care of most of the
> necessary changes:
>
> https://docs.python.org/3/library/2to3.html
>
> Note that 2to3 is will be removed in python 3.13, so I definitely
> recommend doing that transition now. It's probably less work than
> implementing your own separation code.
>
> John
>
> --
> *************************
> John Parejko
> parejkoj at uw.edu
> Rubin Observatory, DIRAC Fellow
> http://staff.washington.edu/parejkoj/
> Department of Physics and Astronomy
> University of Washington, Seattle, WA
> **************************
>
> > On Aug 10, 2023, at 9:18 AM, Didelon Pierre <pierre.didelon at cea.fr>
> wrote:
> >
> > Hi John
> >
> > thank you for your very quick answer.
> > I didn't notice the inappropriate version of the doc not corresponding
> to the astropy version I used.
> > Unfortunately I will not migrate to Python 3, 'cause I don't want to
> "translate" more than a thousand line of code from python2 to 3 :-/
> > I will use another way to calculate angular distance, at least
> approximately,
> > and try to read the appropriate documentation from now on.
> >
> > Best
> > Pierre
> >
> >
> >
> > De : AstroPy <astropy-bounces+pierre.didelon=cea.fr at python.org> de la
> part de John ZuHone <jzuhone at gmail.com>
> > Envoyé : jeudi 10 août 2023 18:02
> > À : Astronomical Python mailing list
> > Objet : Re: [AstroPy] using astropy.coordinates.angular_separation()
> >  Hi Pierre,
> >
> > I should note that you are looking at the page for the "stable" version
> of AstroPy, which is 5.3.1, whereas you are using a very old version of
> AstroPy, for which the docs are here:
> >
> >
> >
> > Based on my casual look, this method is not in this old version. If you
> can, I highly recommend upgrading to the latest version, which also
> necessitates upgrading to Python 3.
> >
> > Best,
> >
> > John
> >
> >> On Aug 10, 2023, at 11:58 AM, Didelon Pierre <pierre.didelon at cea.fr>
> wrote:
> >>
> >>
> >> Hi everyone
> >>
> >> I hope I am not disturbing you with a silly question :-/
> >>
> >> I try to use the astropy.coordinates.angular_separation() utility
> >> (
> https://docs.astropy.org/en/stable/api/astropy.coordinates.angular_separation.html
> )
> >> in python2.7 with  astropy 2.0.16 but it seems not available :-/
> >>
> >> here is the code
> >>
> >> import astropy.coordinates as ac
> >> ...angsep = ac.angular_separation
> (pix_c_coord[0]*pi/180.,pix_ra*pi/180.,pix_c_coord[1]*pi/180.,pix_dec*pi/180.)
> *180./pi
> >>
> >> and the error
> >>
> >> angsep = ac.angular_separation
> (pix_c_coord[0]*pi/180.,pix_ra*pi/180.,pix_c_coord[1]*pi/180.,pix_dec*pi/180.)
> *180./pi AttributeError: 'module' object has no attribute
> 'angular_separation'
> >>
> >> Did I miss something?
> >>
> >> Tank's in advance for any advice
> >>
> >> Pierre Didelon
> >>
> >> Astrophysic Department CEA Saclay
> >> _______________________________________________
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> >> AstroPy at python.org
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> >
> >
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