Generalise the current Factory interface for any Nx2pt factories (including GC multi-tracers)

[arthurmloureiro]

Hi @marcpaterno and @vitenti !

(Putting our discussion from yesterday into an issue as you suggested)

The current implementation for the TwoPoint.from_metadata accepts a wl_factory and a nc_factory with other 2pt probes such as CMB Lensing to be added as something like cmbl_factory due to internal checks in this function:

firecrown/firecrown/likelihood/source_factories.py

Line 8 in 4209e23

def use_source_factory(

What we seemed to have converged on our hacking telecon was to modify this method:

firecrown/firecrown/likelihood/two_point.py

Line 318 in 4209e23

def _from_metadata_single_base(cls, metadata, wl_factory, nc_factory):

Allowing us to call a list of different factories:

all_two_point_functions = tp.TwoPoint.from_metadata(
    metadata_seq=all_two_point_cells,
    factories=[ncf1, ncf2, wlf, cmblf],
)

where the combination of which probes to cross-correlate with are inside the all_two_point_cells metadata.

I also understand we finished the telecon with the understanding that currently adding this support would not fix the support for GC multi-tracers due to their measurements being the same Galaxies.COUNTS, but I think @vitenti had a potential solution to this.

[arthurmloureiro]

Tagging also @VGozzi here as he as experience with ~hacking GC Multi-tracers in Firecrown :)