anisotropyT {CoSMoS}

Anisotropy transformation

Description

Provides parametric functions that describe different types of planar deformation fields, including affine (rotation and stretching), and swirl-like deformation. For more details see Papalexiou et al.(2021) and references therein.

Usage

anisotropyT(id, ...)

Arguments

id

anisotropy type id (affine, swirl, and wave)

...

additional arguments (vector of coordinates and parameters of the anisotropy transformations)

References

Papalexiou, S. M., Serinaldi, F., Porcu, E. (2021). Advancing Space-Time Simulation of Random Fields: From Storms to Cyclones and Beyond, Water Resources Research, doi: 10.1029/2020WR029466

Examples

library(CoSMoS)

## specify coordinates
m = 25
aux <- seq(0, m - 1, length = m)
coord <- expand.grid(aux, aux)

## get the anisotropy field
at1 <- anisotropyT('affine',
                 spacepoints = coord,
                 phi1 = 0.5,
                 phi2 = 2,
                 phi12 = 0,
                 theta = -pi/3)
at2 <- anisotropyT('swirl',
                 spacepoints = coord,
                 x0 = floor(m / 2),
                 y0 = floor(m / 2),
                 b = 10,
                 alpha = 1.5 * pi)
at3 <- anisotropyT('wave',
                 spacepoints = coord,
                 phi1 = 0.5,
                 phi2 = 2,
                 beta = 3,
                 theta = 0)

## visualize anisotropy field
aux = data.frame(lon = at2[ ,1], lat = at2[ ,2], id1 = rep(1:m, each = m), id2 = rep(1:m, m))
ggplot(aux, aes(x = lon, y = lat)) +
geom_path(aes(group = id1)) +
geom_path(aes(group = id2)) +
geom_point(col = 2) +
theme_light()