Need help with index of nearest node

[ogonek]

I still have some difficulties wrapping my head around those sample nodes.

what I intend to do:
the points in the circle on the left should store index and position attributes about their nearest neighbours in the group on the right. Is that possible? I don’t get the group ID input and the manual isn’t that helpful.

[ogonek]

I think I solved it with a Sample Nearest node. Still don’t know how that Group ID input works.

. . . . . . . .

[zeroskilz]

Group ID tells the Index of Nearest to only test other elements with the same Group ID.