Compute Spatial Correlograms

DESCRIPTION:

Compute spatial correlograms of spatial data or residuals.

USAGE:

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

REQUIRED ARGUMENTS:

krig
trend-surface or kriging object with columns x, y, and z
nint
number of bins used

OPTIONAL ARGUMENTS:

plotit
logical for plotting
...
parameters for the plot

VALUE:

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

SIDE EFFECTS:

Plots the correlogram if plotit = T.

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.

SEE ALSO:

EXAMPLES:

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