[Feature Request] Specify multirun sweeps in a config file

[zaccharieramzi]

🚀 Feature Request

I would like to be able to specify multirun sweeps in a config file.

Motivation

Is your feature request related to a problem? Please describe.
I would like to be able to define my grid search in config files in order to have a way to save orderly rather than having to go through my search history for the last grid searches.

Pitch

Describe the solution you'd like
Currently, the way to specify a sweep is via the command line like python my_app.py -m +test.var=1,2. I would like to be able to pass the sweep as a config file, for example ``python my_app.py -m +test=grid_searchwheretest/grid_search.yaml` is in the config search path.

The content of test/grid_search.yaml could be for example:

var@sweep: 
  - 1
  - 2

The @sweep is not part of the grammar but it could be to differentiate config variables that are not sweepable but really just lists.

Describe alternatives you've considered
I could have all my grid searches in scripts that are versioned but it doesnt feel natural and promotes a lot of copy pasting that I would like to avoid.

Are you willing to open a pull request? (See CONTRIBUTING)
Yes

Additional context

I opened an SO question on this topic, but it didnt get a lot of attention and I figured that it might be because there is simply no solution currently.

[pixelb]

Yes this is something that is on our radar to implement hopefully for next release

[zaccharieramzi]

Cool!
I'd be happy to help should you need it

[pixelb]

Does commit 20bd227 cover your use case?
That was implemented as part of issue #1376

[zaccharieramzi]

I think it does mostly so cool! Sorry I hadn't seen #1376

I have one additional feature request linked to this: do you think it would be possible to make it work with this type of sweep? i.e. python my_app.py -m '+top={a:10,b:20},{a:100,b:200}'

If you want I can repost that request on #1376

[pixelb]

closing as a duplicate of #1376 for now.
Feel free to further discuss there. thanks