rmaxstab {SpatialExtremes} | R Documentation |
This functions generates realisation from a max-stable random field.
rmaxstab(n, coord, cov.mod = "gauss", grid = FALSE, control = list(), ...)
n |
Integer. The number of observations. |
coord |
A vector or matrix that gives the coordinates of each location. Each row corresponds to one location - if any. |
cov.mod |
A character string that gives the max-stable model. This must be one of "gauss" for the Smith model or "whitmat", "cauchy", "powexp" and "bessel" for the Schlather model with the given correlation family. |
grid |
Logical. Does the coordinates represent grid points? |
control |
A named list with arguments 'nlines' (number of lines of the TBM simulation), 'method' the name of the simulation method - must be one of 'exact' or 'tbm', and 'uBound' the uniform upper bound. See details. |
... |
The parameters of the max-stable model. See details. |
Users must supply the parameters for the max-stable model. For the
Schlather model, users should supply the "sill", "range" and "smooth"
parameter values. For the Smith model, if coord
is univariate
you must specify var
, otherwise users should supply the
covariance parameters i.e. parameters with names such as cov11
,
cov12
, ...
Here are the details for each allowed components of 'control'. If
'method' is NULL
(default), the function tries to find the
most appropriate simulation technique. If 'nlines' is NULL
, it
is set to 1000. If 'uBound' is NULL
, it is set to reasonable
values - for example 3.5 for the Schalther model.
A matrix containing observations from the required max-stable
model. Each column represents one stations. If grid = TRUE
, the
function returns an array of dimension nrow(coord) x nrow(coord) x n.
Mathieu Ribatet
Schlather, M. (2002) Models for Stationary Max-Stable Random Fields. Extremes 5:1, 33–44.
Smith, R. L. (1990) Max-stable processes and spatial extremes. Unpublished manuscript.
fitmaxstab
## 1. Smith's model set.seed(8) x <- y <- seq(0, 10, length = 200) coord <- cbind(x, x) data <- rmaxstab(1, coord, cov11 = 9/8, cov12 = 0, cov22 = 9/8, grid = TRUE) ##We change to unit Gumbel margins for visibility filled.contour(x, y, log(data[,,1]), color.palette = terrain.colors) ## 2. Schlather's model coord <- matrix(runif(100, 0, 15), ncol = 2) data <- rmaxstab(100, coord, cov.mod = "whitmat", sill = 1, range = 10, smooth = 1)