Clustering

clustering.txt

Start with a list of clusters:
a, b, x, c, x, x, d, e, f, g, x, h

Select out clusters to try and find a place for:

a, b, c, d, e, f, g, h

Map over a method to (optionally) assign a place (pN) to each cluster:
(this is done with a DelegateClass containing the place or nil)

a(p1), b(p2), c(nil), d(p1), e(p1), f(nil), g(p1), h(p1)

Merge together clusters with the same place, who were originally adjacent:

a(p1), b(p2), c(nil), de(p1), f(nil), g(p1), h(p1)

d and e are merged, because they're at the same place;
g and h aren't, because there was originally an x cluster between them.