Scope question: "table selection" regions?

[keflavich]

In discussion about how to save Glue selections, @eteq raised the possibility of serializing data selection. Currently, regions is only intended to identify regions on the sky and maybe associated with spectral depth. Maybe we want to be able to serialize region selections associated with table columns? I think that sort of selection would fall under astropy.regions eventually, but we probably don't want to expand the scope of this repository just yet.

[keflavich]

cc @astrofrog since this is gluey

[cdeil]

@keflavich - Can you clarify what you mean?

If you have a table with positions, then a region selection results in a boolean mask with True / False for each row if the position is inside or outside. You can store this mask as a new column in the table, that's a kind of serialisation of the selection.

Probably I misunderstand completely - what kind of object is the "selection"? Is it a separate object or attached to the Table or Region object? Can you give a minimal example what we might want to add?

[keflavich]

I think the idea was to allow coordinate-like selections on a table, e.g., a region in V-U vs V space in a color-magnitude diagram. So if you used "brushing" selection as in glue, you could serialize that.