Old school D3 from simpler times
K-D Tree Nearest Neighbors (k-NN)
k-d tree nearest neighbors search
(k-NN). The red dots are the 10 nearest neighbors.
Orange dots are scanned and not selected.
Compare with this block that implements
a k nearest neighbor search using a quadtree instead of a k-d tree.
The algorithm for this search came from
this course handout.
Note that the "k" in k-d tree need not be the same number as the "k" in
the k-NN search. This is just the letter used to denote a positive integer
for both algorithms.