Also, this paper has some example R code (in Ecological Archives) to
simulate a track from bivariate random walk.
@ARTICLE{patterson2010using,
author = {Patterson, T.A. and McConnell, B.J. and Fedak, M.A. and
Bravington,
M.V. and Hindell, M.A.},
title = {{Using GPS data to evaluate the accuracy of state-space methods
for
correction of Argos satellite telemetry error}},
journal = {Ecology},
year = {2010},
volume = {91},
pages = {273--285},
number = {1},
publisher = {Eco Soc America}
}
I'm not sure if the supplement is availalbe publicly, but if not and you
don't have access you could perhaps email the author:
http://www.esapubs.org/archive/ecol/E091/020/suppl-1.htm#anchorFilelist
Cheers, Mike.
On Sat, Oct 2, 2010 at 12:44 PM, Michael Sumner <mdsum...@gmail.com> wrote:
> There's an example in the trip package function filter.penSS that might be
> of interest, provided by my supervisor Simon Wotherspoon. You could adjust
> the values to get 30 min intervals.
>
> ## Fake some data
>
> ## Brownian motion tethered at each end
> brownian.bridge <- function(n, r) {
> x <- cumsum(rnorm(n, 0, 1))
> x <- x - (x[1] + seq(0, 1, length = n) * (x[n] - x[1]))
> r * x
> }
>
> ## Number of days and number of obs
> days <- 50
> n <- 200
>
> ## Make separation between obs gamma distributed
> x <- rgamma(n, 3)
> x <- cumsum(x)
> x <- x/x[n]
>
> ## Track is lissajous + brownian bridge
> b.scale <- 0.6
> r.scale <- sample(c(0.1, 2, 10.2), n, replace = TRUE, prob = c(0.8,
> 0.18, 0.02))
> set.seed(44)
>
> tms <- ISOdate(2001, 1, 1) + trunc(days * 24 * 60 * 60 *x)
> lon <- 120 + 20 * sin(2 * pi * x) + brownian.bridge(n, b.scale) +
> rnorm(n, 0, r.scale)
> lat <- -40 + 10 *(sin(3 * 2 * pi * x) + cos(2 * pi * x) - 1) +
> brownian.bridge(n, b.scale) + rnorm(n, 0, r.scale)
>
> tr <- new("trip", SpatialPointsDataFrame(cbind(lon, lat),
> data.frame(gmt = tms, id = "lbb")), TimeOrderedRecords(c("gmt", "id")))
>
> On Sat, Oct 2, 2010 at 7:30 AM, Andy Bunn <andy.b...@wwu.edu> wrote:
>
>> > -----Original Message-----
>> > From: r-sig-geo-boun...@stat.math.ethz.ch [mailto:r-sig-geo-
>> > boun...@stat.math.ethz.ch] On Behalf Of Roberto Badilla Fuentes
>> > Sent: Friday, October 01, 2010 12:42 PM
>> > To: r-sig-geo
>> > Subject: [R-sig-Geo] Random Movement Generator
>> >
>> > Hi All,
>> >
>> > Is there a functionality in R that allows for the creation of random
>> > path or
>> > trajectory? Probably Brownian Motion can help but I'd like to output
>> > the
>> > data points and be able to have the points separated, say every 30
>> > minutes.
>>
>> I've used like this before in class to teach about random walks. Maybe
>> this will get you going? HTH, Andy
>>
>> require(sp)
>> xinit <- 0
>> yinit <- 0
>> d2move <- 1
>> nsteps <- 99
>> x <- c(xinit,rep(NA,nsteps))
>> y <- c(yinit,rep(NA,nsteps))
>> for(i in 2:(nsteps+1)){
>> theta <- runif(1,pi/180,360*pi/180)
>> xi <- d2move * cos(theta)
>> yi <- d2move * sin(theta)
>> x[i] <- x[i-1] + xi
>> y[i] <- y[i-1] + yi
>> }
>> plot(x,y,type='b')
>> xy <- SpatialPoints(cbind(x,y))
>> str(xy)
>>
>>
>>
>>
>>
>>
>> >
>> >
>> > I also tried BM{sde}. Is there a way plot the points generated?
>> >
>> > Thanks in advance
>> > Roberto
>> >
>> > [[alternative HTML version deleted]]
>> >
>> > _______________________________________________
>> > R-sig-Geo mailing list
>> > R-sig-Geo@stat.math.ethz.ch
>> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo@stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>
>
>
> --
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsum...@gmail.com
>
--
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsum...@gmail.com
[[alternative HTML version deleted]]
_______________________________________________
R-sig-Geo mailing list
R-sig-Geo@stat.math.ethz.ch
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
