Semivariance Values For a Given Variogram Model

Generates a semivariance values given a variogram model

Usage

variogramLine(object, maxdist, n = 200, min = 1.0e-6 * maxdist, 
  dir = c(1,0,0), covariance = FALSE, ..., dist_vector, debug.level = 0)

Arguments

object: variogram model for which we want semivariance function values
maxdist: maximum distance for which we want semivariance values
n: number of points
min: minimum distance; a value slightly larger than zero is usually used to avoid the discontinuity at distance zero if a nugget component is present
dir: direction vector: unit length vector pointing the direction in x (East-West), y (North-South) and z (Up-Down)
covariance: logical; if TRUE return covariance values, otherwise return semivariance values
...: ignored
dist_vector: numeric vector or matrix with distance values
debug.level: gstat internal debug level

Value

a data frame of dimension (n x 2), with columns distance and gamma (semivariances or covariances), or in case dist_vector is a matrix, a conforming matrix with semivariance/covariance values is returned.

Note

variogramLine is used to generate data for plotting a variogram model.

Author

Edzer Pebesma

Examples

variogramLine(vgm(5, "Exp", 10, 5), 10, 10)
#>        dist    gamma
#> 1   0.00001 5.000005
#> 2   1.11112 5.525807
#> 3   2.22223 5.996316
#> 4   3.33334 6.417346
#> 5   4.44445 6.794100
#> 6   5.55556 7.131234
#> 7   6.66667 7.432915
#> 8   7.77778 7.702871
#> 9   8.88889 7.944439
#> 10 10.00000 8.160603
# anisotropic variogram, plotted in E-W direction:
variogramLine(vgm(1, "Sph", 10, anis=c(0,0.5)), 10, 10)
#>        dist     gamma
#> 1   0.00001 0.0000030
#> 2   1.11112 0.3278489
#> 3   2.22223 0.6227728
#> 4   3.33334 0.8518530
#> 5   4.44445 0.9821677
#> 6   5.55556 1.0000000
#> 7   6.66667 1.0000000
#> 8   7.77778 1.0000000
#> 9   8.88889 1.0000000
#> 10 10.00000 1.0000000
# anisotropic variogram, plotted in N-S direction:
variogramLine(vgm(1, "Sph", 10, anis=c(0,0.5)), 10, 10, dir=c(0,1,0))
#>        dist     gamma
#> 1   0.00001 0.0000015
#> 2   1.11112 0.1659821
#> 3   2.22223 0.3278475
#> 4   3.33334 0.4814824
#> 5   4.44445 0.6227716
#> 6   5.55556 0.7475999
#> 7   6.66667 0.8518521
#> 8   7.77778 0.9314130
#> 9   8.88889 0.9821674
#> 10 10.00000 1.0000000
variogramLine(vgm(1, "Sph", 10, anis=c(0,0.5)), dir=c(0,1,0), dist_vector = 0.5)
#>   dist     gamma
#> 1  0.5 0.0749375
variogramLine(vgm(1, "Sph", 10, anis=c(0,0.5)), dir=c(0,1,0), dist_vector = c(0, 0.5, 0.75))
#>   dist     gamma
#> 1 0.00 0.0000000
#> 2 0.50 0.0749375
#> 3 0.75 0.1122891