Generating Four Sublists of Points with Adjacency Conditions in GHpython

O = b
▭ = a

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when I want to run this code some seeds in one of the sublists can not select a point from list b because the condition (the distance between the selected point and two other points in the sublist is smaller than 2.5) is not met. How can I have four sublists correctly with this condition?
@Mahdiyar