How does 'ranked by' work?

[NigelG]

:ranked by - how it works

Hey! I was wondering if someone could expand on this function. Seems powerful on the face of things but how does it measure similarities? Has anyone got a working example or could explain below in more detail? :ranked by… This lets you rank a list of things by how similar or how different they are from a target element (which should be of the same type). This can be used if you want to match people for a dating app, for instance.