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Improve support for unit systems in astropy.units #11525
Description
The current support for unit systems in Astropy is pretty minimal and only extends to major unit systems like CGS, SI, Imperial (as modules with implemented units). There have been various related feature requests, discussions, and attempts to improve this. For example:
- Feature request for more specific galactic/extragalactic unit systems Add "extragalactic" and "galactic" unit systems #703
- Experimental port of
UnitSystemclass from mygalapackage to Astropy [EXP] Add UnitSystem class to support custom unit systems #6065 - Feature request for setting the global unit system as a science state, to control (globally) output from any unit-aware function (this comment)
- Being able to (de)compose in prefix units (decompose does not accept PrefixUnits as bases #5615).
Let's use this issue as a new meta-issue for discussing improving support for unit systems in astropy.units!
Activity
nstarman commentedon Apr 12, 2021
While this is linked to in the opening comment, I'd like to mention here the SymPy implementation of unit systems as an interesting example implementation. They have a very formal structure, allowing for decomposition into any orthogonal set of units, and it's easy to make new systems. I think it's quite close to the
galasuggestion.Their documentation is a bit poor, but the code is pretty clear.