Figure 1:

Examples of four orderings of 400 locations on a 20 × 20 grid. From left to right are completely random, maximum minimum distance, middle out, and sorted on vertical coordinate. On the top row, the black circles are ordered 1–50, circled point is number 50, and squared points are 30 nearest neighbors to point 50 among previous points. Bottom row is the same for point ordered number 330.