solar metallicity value saved in sp object

[dnarayanan]

Hi,

[Feature request]

Would it be possible to save the value used for solar metallicity in the sp object? These are different for different isochrones, which makes code on our end kind of clunky like appended below :). If this were in the sp object it would be super convenient on our end for powderday.

thanks!
-desika

print(f'\n----------------------------------------------\nSetting solar metallicity value')
if 'mist' in isochrone:
    print('isochrone = mist')
    cfg.par.solar = 0.0142
    print(f'solar metallicity = {cfg.par.solar}')
elif 'bsti' in isochrone:
    print('isochrone = basti')
    cfg.par.solar = 0.020
    print(f'solar metallicity = {cfg.par.solar}')
elif 'gnva' in isochrone:
    print('isochrone = geneva')
    cfg.par.solar = 0.020
    print(f'solar metallicity = {cfg.par.solar}')
elif 'prsc' in isochrone:
    print('isochrone = parsec')
    cfg.par.solar = 0.01524
    print(f'solar metallicity = {cfg.par.solar}')
elif 'pdva' in isochrone:
    print('isochrone = padova')
    cfg.par.solar = 0.019
    print(f'solar metallicity = {cfg.par.solar}')
elif 'bpss' in isochrone:
    print('isochrone = bpass')
    cfg.par.solar = 0.020
    print(f'solar metallicity = {cfg.par.solar}')
print('----------------------------------------------')

[moustakas]

@dnarayanan it looks like @bd-j has already self-assigned this (useful) suggestion, but for the time being a one-time dictionary might simplify your code a bit. In case it's useful, something like:

Ziso = {'mist': ('mist', 0.0142), 'bsti': ('basti', 0.020), 
  'gnva': ('geneva', 0.020), 'prsc': ('parsec', 0.01524), 
  'pdva': ('padova', 0.019)}

iso, Zsun = Ziso[isochrone]
cfg.par.solar = Zsun
print('isochrone, solar metallicity = {} ({}), {:.4f}'.format(iso, isochrone, Zsun))

[dnarayanan]

that is much nicer -- thanks John!

[dnarayanan]

(I should note -- for the purposes of this enhancement request -- is that one thing I'm worried about is that if the definition of 'solar' changes for a set of isochrones one day, that if I have it hardcoded in powderday, we'll be making an error. that's why I'd love to be able to grab it directly from the sp object)

[bd-j]

As of #182 there is a solar_metallicity attribute of StellarPopulation that gives the isochrone solar metallicity definition being used in FSPS. Hope this addresses the issue, but please do reopen if there is some other behavior or functionality you had in mind @dnarayanan, thanks.