# anisotropyTswirl: Swirl anisotropy transformation In CoSMoS: Complete Stochastic Modelling Solution

## Description

Swirl anisotropy transformation.

## Usage

 `1` ```anisotropyTswirl(spacepoints, x0, y0, b, alpha) ```

## Arguments

 `spacepoints` vector of coordinates (2 x d), where d is the number of locations/grid points `x0` x coordinate of the center of the swirl deformation `y0` y coordinate of the center of the swirl deformation `b` scaling parameter controlling the swirl deformation `alpha` rotation angle

## References

Ligas, M., Banas, M., Szafarczyk, A. (2019). A method for local approximation of a planar deformation field. Reports on Geodesy and Geoinformatics, 108(1), 1-8, doi: 10.2478/rgg-2019-0007

Papalexiou, S.M., Serinaldi, F., Porcu, E. (2021). Advancing Space-Time Simulation of Random Fields: From Storms to Cyclones and Beyond. Water Resources Research, 57, e2020WR029466, doi: 10.1029/2020WR029466

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18``` ```## specify coordinates m = 25 aux <- seq(0, m - 1, length = m) coord <- expand.grid(aux, aux) at <- anisotropyTswirl(spacepoints = coord, x0 = floor(m / 2), y0 = floor(m / 2), b = 10, alpha = 1.5 * pi) ## visualize transformed coordinate system aux = data.frame(lon = at[ ,1], lat = at[ ,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() ```

CoSMoS documentation built on May 30, 2021, 1:06 a.m.