simm.levy: Simulates a Levy Walk

Description

This function simulates a Levy walk

Usage

simm.levy(date = 1:500, mu = 2, l0 = 1, x0 = c(0, 0),
          id = "A1", burst = id, typeII = TRUE,
          proj4string=CRS())

Value

an object of class ltraj

Arguments

date: a vector indicating the date (in seconds) at which relocations should be simulated. This vector can be of class POSIXct. *Note that the time lag between two relocations should be constant* (regular trajectories required)
mu: The exponent of the Levy distribution
l0: The minimum length of a step
x0: a vector of length 2 containing the coordinates of the startpoint of the trajectory
id: a character string indicating the identity of the simulated animal (see help(ltraj))
burst: a character string indicating the identity of the simulated burst (see help(ltraj))
typeII: logical. Whether the simulated trajectory should be of type II (TRUE, time recorded) or not (FALSE, time not recorded). See help(ltraj).
proj4string: a valid CRS object containing the projection information (see ?CRS from the package sp).

Author

Clement Calenge clement.calenge@ofb.gouv.fr

Details

This function simulates a Levy flight with exponent mu. This is done by sampling a random relative angle from a uniform distribution (-pi, pi) for each step, and a step length generated by dt * (l0 * (runif(1)^(1/(1 - mu))))

References

Bartumeus, F., da Luz, M.G.E., Viswanathan, G.M. Catalan, J. (2005) Animal search strategies: a quantitative random-walk analysis. Ecology, 86: 3078--3087.

Examples

Run this code


suppressWarnings(RNGversion("3.5.0"))
set.seed(411)
w <- simm.levy(1:500, mu = 1.5, burst = "mu = 1.5")
u <- simm.levy(1:500, mu = 2, burst = "mu = 2")
v <- simm.levy(1:500, mu = 2.5, burst = "mu = 2.5")
x <- simm.levy(1:500, mu = 3, burst = "mu = 3")
par(mfrow=c(2,2))
lapply(list(w,u,v,x), plot, perani=FALSE)

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