closest_subsets: Set of increasing sets from left to right of input vector.
Description
Returns a set of the increasing sets of the input vector v,
in the sense that the first set contains the first element of v,
the second set the first and second elements of v, and so on.
Usage
closest_subsets(v)
Arguments
v
A vector. Meant to represent the \(k\) nearest neighbors
of a location, the first element being the integer identifier of the
location itself.