Group Light speed test.ipynb

Why not map all on_states into a 'combined' state first?
(just make each attribute into a list of values, order is not important right?)

So you would work with:

on_states: {
   'brightness': [255, 232, 200]
    'xy_color': [[1.0, 1.0],[1.2, 1.2],[1.5, 1.1],
    'rgb_color': [[255, 255, 255],[255, 255, 255],[255, 255, 255]]
    'white_value': [0, 0, 0.1]
    'supported_features': [1, 2, 345]
})

Then you only need to iterate the states once and can just pass each attributes list to your reduce function.

Oh, and that first (and faster) function a A LOT more readable. (that counts too imo)