zorder {tlrmvnmvt}

Index locations on the 2D plane

Description

Index a set of locations of the 2D plane with a Z-curve, when they are scaled into the unit square. The goal of this function is to make locations close in geometry also close in the index. When partitioned into clusters, the inter-cluster correlation is more likely to be low-rank.

Usage

zorder(geom)

Arguments

geom

2D geometry, each row represents the location of a variable. The geometry should be scaled into the unit square, (0,1) X (0,1)

Value

A vector of indices based on the Z-curve.

Author(s)

Jian Cao, Marc Genton, David Keyes, George Turkiyyah

References

Foley, James, Andries van Dam, Steven Feiner, and John Hughes. "Computer Graphics: Principle and Practice". Addison-Wesley Publishing Company. Reading, Massachusetts: 1987. pages 870-871

Examples

  n = 333
  set.seed(0)
  geom = matrix(runif(n*2), n, 2)
  idx = zorder(geom)
  idx