spatial (version 7.3-18)

correlogram: Compute Spatial Correlograms

Description

Compute spatial correlograms of spatial data or residuals.

Usage

correlogram(krig, nint, plotit = TRUE,  ...)

Value

x and y coordinates of the correlogram, and cnt, the number of pairs averaged per bin.

Arguments

krig

trend-surface or kriging object with columns x, y, and z

nint

number of bins used

plotit

logical for plotting

...

parameters for the plot

Side Effects

Plots the correlogram if plotit = TRUE.

Details

Divides range of data into nint bins, and computes the covariance for pairs with separation in each bin, then divides by the variance. Returns results for bins with 6 or more pairs.

References

Ripley, B. D. (1981) Spatial Statistics. Wiley.

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.

See Also

variogram

Examples

data(topo, package="MASS")
topo.kr <- surf.ls(2, topo)
correlogram(topo.kr, 25)
d <- seq(0, 7, 0.1)
lines(d, expcov(d, 0.7))