simExpCorrRF: Create a Gaussian random field with negative exponential...

In AHMbook: Functions and Data for the Book 'Applied Hierarchical Modeling in Ecology' Vols 1 and 2

Create a Gaussian random field with negative exponential correlation

Description

Function creates Gaussian random field with negative exponential correlation and visualizes correlation and random field.

Previous versions used RandomFields, but that is not currently available on CRAN. fields is now used instead, but it cannot deal with large values of size and theta. If you have RandomFields installed (perhaps by getting it from the CRAN archive), you can load a version of simExpCorrRF that supports it with source(system.file("RandomFieldsSupport", "simExpCorrRF.R", package="AHMbook")).

Usage

simExpCorrRF(variance = 1, theta = 1, size = 50, seed = NA, show.plots = TRUE)

Arguments

variance	variance of field.
theta	parameter governing spatial correlation (=1/phi) ("large theta means high correlation") Note that RMexp (which is used internally) is specified in terms of phi = 1/theta.
size	number of pixels along each side of the square site.
seed	used to generate reproducible output.
show.plots	if TRUE, the result will be displayed.

Value

A list with the values of the input arguments and the following additional elements:

field	the random field variable, a vector of length size^2
grid	the grid corresponding to field

Author(s)

Marc Kéry & Andy Royle

References

Kéry, M. & Royle, J.A. (2021) Applied Hierarchical Modeling in Ecology AHM2 - 9.

Examples

# Run the function with default values and look at the output
str(tmp <- simExpCorrRF())

AHMbook documentation built on Sept. 12, 2024, 6:37 a.m.