Make coordinates.solar_system_ephemeris accept local ephemeris file

astropy.coordinates.solar_system_ephemeris.set() currently (version 3.1) has the possibility of accepting one of the presets (e.g. 'builtin', 'de430') or an URL pointing to another ephemeris to use. But if I have an ephemeris already downloaded to a local file, it does not allow me to pass the path to this local file to use.

It doesn't work to specify the local file in URL format either i.e. "file://path/to/file.bsp".

My suggestion would be to either make it possible to specify a local file either using the URL format specified above or allowing to pass the path to the local file directly.

Yes, that is a reasonable request and should be supported IMHO. It looks like this logic below does not yet support a local data file:

astropy/astropy/coordinates/solar_system.py

Lines 158 to 172 in 33962dd

    
           else: 
        
               try: 
        
                   urlparse(value) 
        
               except Exception: 
        
                   raise ValueError('{} was not one of the standard strings and ' 
        
                                    'could not be parsed as a URL'.format(value)) 
        
           try: 
        
               from jplephem.spk import SPK 
        
           except ImportError: 
        
               raise ImportError("Solar system JPL ephemeris calculations require " 
        
                                 "the jplephem package " 
        
                                 "(https://pypi.python.org/pypi/jplephem)") 
        
           return SPK.open(download_file(value, cache=True))

The workaround for now, I guess, is to upload your data file to the internet, so it can be downloaded back and cached... 😬

or just run python -m http.server in the directory it is in so you can put in a localhost:8000 url?!

@Cadair

@Cadair , you mean http.server or http.severe?

@rhandberg

Very much in favour - this was an oversight in the implementation. Possibly the way to go would be to do the download_file(value) only in the branch where a URL is detected, and otherwise just try SPK.open(value) directly.

@rhandberg - would you be able to try this, and perhaps make a PR?

@mhvk

@mhvk - I'll give it a try... PR coming soon!

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Make coordinates.solar_system_ephemeris accept local ephemeris file #8750

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	else:
	try:
	urlparse(value)
	except Exception:
	raise ValueError('{} was not one of the standard strings and '
	'could not be parsed as a URL'.format(value))

	try:
	from jplephem.spk import SPK
	except ImportError:
	raise ImportError("Solar system JPL ephemeris calculations require "
	"the jplephem package "
	"(https://pypi.python.org/pypi/jplephem)")

	return SPK.open(download_file(value, cache=True))

Make coordinates.solar_system_ephemeris accept local ephemeris file #8750

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pllim commented on May 24, 2019

Cadair commented on May 24, 2019

pllim commented on May 24, 2019

mhvk commented on May 24, 2019

rhandberg commented on May 28, 2019

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