Source version in Model

[bastiencarreres]

Hi,
First, thank you for this library!
I'm working on SN Ia simulation and I would keep track of the Source version that I can use in some meta-file to re-load the same model when needed. I have remarked that the class Model(_ModelBase) has not a version arg that can be passed to get_source. Is it something that can be implemented in a future version?

[benjaminrose]

@bastiencarreres, we should be able to implement this. Do you have an example script/test that you would like to see work?

Also, @cwwalter this seems like something that might help the next round of DESC simulations as well.

[bastiencarreres]

Hi @benjaminrose , I was thinking of something simple, that could be used for fit or simulation, as for example

import sncosmo as snc
model = snc.Model('salt2', version='2.4')

In the __init__ of Models there is already that:

def __init__(self, source, effects=None,
                effect_names=None, effect_frames=None):
       # Set source and add source parameter names
       self._source = get_source(source, copy=True)

where the get_source(source, copy=True) has already a version parameter in its definition but not used here.
Is adding version in the __init__ something that could work?

def __init__(self, source, version=None, effects=None,
                effect_names=None, effect_frames=None):
       # Set source and add source parameter names
       self._source = get_source(source, version=version, copy=True)

I have tested snc.models._SOURCES.retrieve('salt2', version='2.4') and it seems to work.

[cwwalter]

Also tagging @jchiang87.

[cwwalter]

Tagging @JoanneBogart.

[benjaminrose]

@bastiencarreres, yeah, I think we should add this. This allows people to use sncosmo.Model with a string, but still fully define their source file. Currently, you would need to create a full sncosmo.Source object to do this. There are not many sources with multiple versions, so this has not come up before, but DESC is also asking for this. I think we should add a dictionary and not mess with the order of the input variables. I think we should do something like this:

def __init__(self, source, effects=None,
                effect_names=None, effect_frames=None, source_params={}):
       # Set source and add source parameter names
       self._source = get_source(source, copy=True, **source_params)

Then you can use snc.models._SOURCES.retrieve('salt2', source_params={'version': '2.4'}). It is a bit more verbose, but helps keep the default process smoother & backwards compatible.

@JoanneBogart, with this patch, we can add a similar version value to skyCatalogs's class SNObject.

[MickaelRigault]

Hello guys, I'm also interested with this functionality. The proposition from @bastiencarreres looks like the good one to me.
We want to be able to do

model = sncosmo.Model("salt2", version="2.4")

or a parsable string (that may helps the dev as no new variables)

model = sncosmo.Model("salt2 v=2.4")

or (and this would be cleaner from the start: forbid the fact that sources may have the same Name (so rename "salt2"->salt2.4, salt2T21, salt2B22 etc)

model = sncosmo.Model("salt2.4")