vgmLags: Lag-distance classes for variogram estimation

Description

Computation of lag-distance classes for variogram estimation.

Usage

vgmLags(coords, n.lags = 7, type = "exp", cutoff = 0.5, base = 2,
  zero = 0.001, count = "pairs")

Arguments

coords

Data frame or matrix with the projected x- and y-coordinates.

n.lags

Integer value defining the number of lag-distance classes that should be computed. Defaults to n = 7.

type

Character value defining the type of lag-distance classes that should be computed, with options "equi" (equidistant) and "exp" (exponential). Defaults to type = "exp".

cutoff

Numeric value defining the fraction of the diagonal of the rectangle that spans the data (bounding box) that should be used to set the maximum distance up to which lag-distance classes should be computed. Defaults to cutoff = 0.5, i.e. half the diagonal of the bounding box.

base

Numeric value defining the base of the exponential expression used to create exponentially spaced lag-distance classes. Used only when type = "exp". Defaults to base = 2, i.e. the width of the rightmost lag-distance classes is equal to half the diagonal of cutoff, and so on.

zero

Numeric value setting the minimum pair-wise separation distance that should be used to compute the lag-distance classes. Defaults to zero = 0.0001.

count

Should the number of points ("points") or point-pairs ("pairs") per lag-distance class be computed? Defaults to count = "pairs".

Value

Vector of numeric values with the lower and upper boundaries of the lag-distance classes. The number of points or point-pairs per lag-distance class is returned as an attribute.

References

Truong, P. N.; Heuvelink, G. B. M.; Gosling, J. P. Web-based tool for expert elicitation of the variogram. Computers and Geosciences. v. 51, p. 390-399, 2013.

Examples

Run this code

# NOT RUN {
data(meuse, package = "sp")
lags_points <- vgmLags(coords = meuse[, 1:2], count = "points")
lags_pairs <- vgmLags(coords = meuse[, 1:2], count = "pairs")
# }