variogram {SpatialExtremes}

Empirical variogram

Description

This function computes the empirical variogram.

Usage

variogram(data, coord, n.bins, xlab, ylab, angles = NULL, add = FALSE,
xlim = c(0, max(dist)), ...)

Arguments

data

A matrix representing the data. Each column corresponds to one location.

coord

A matrix that gives the coordinates of each location. Each row corresponds to one location.

n.bins

The number of bins to be used. If missing, pairwise madogram estimates will be computed.

xlab, ylab

The x-axis and y-axis labels. May be missing. Note that ylab must have the same length has which.

angles

A numeric vector. A partition of the interval (0, \pi) to help detecting anisotropy.

add

Logical. If TRUE, the plot is added to the current figure; otherwhise (default) a new plot is computed.

xlim

A numeric vector of length 2 specifying the x coordinate range.

...

Additional options to be passed to the plot function.

Value

A graphic and (invisibly) a matrix with the lag distances and the empirical variogram estimates.

Author(s)

Mathieu Ribatet

See Also

fmadogram, lmadogram

Examples

n.site <- 20
n.obs <- 100
coord <- matrix(runif(2 * n.site, 0, 10), ncol = 2)
data <- rgp(n.obs, coord, "powexp", sill = 2, range = 3, smooth = 1)
variogram(data, coord)