clustering vs. random

Let's say there's a street with 150 houses on it. If I want to
determine whether the 25 red houses were clustered together, as opposed
to distributed randomly among the entire street, what would be the best
test for this?

Expanding this, how do we determine whether houses tend to be clustered
according to color?

Assume that the houses are not equally spaced along the street; the
next-door distances are log-normal distributed.

Thanks for any insight!
-Dave

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