#### SCR density surface simulation
library(openpopscr)
# set number of threads for parallel processing
RcppParallel::setThreadOptions(numThreads = 1)
# setup simulations -------------------------------------------------------
set.seed(14919)
nsims <- 100
ests <- vector(mode = "list", length = nsims)
# set truth
true_par <- list(D = 1000, lambda0 = 0.2, sigma = 20)
# make detectors array
detectors <- make.grid(nx = 7, ny = 7, spacing = 20, detector = "count")
# make mesh
mesh <- make.mask(detectors, buffer = 100, nx = 64, ny = 64, type = "trapbuffer")
# spatial density effect
x.std <- scale(mesh[,1])
y.std <- scale(mesh[,2])
logD <- log(true_par$D) + 0.2 * x.std - 0.3 * y.std
ihp <- exp(logD) / true_par$D
# set number of occasions to simulate
n_occasions <- 5
# create formulae
form <- list(lambda0 ~ 1,
sigma ~ 1,
D ~ x + y)
# simulation --------------------------------------------------------------
progbar <- utils::txtProgressBar(min = 0, max = nsims, style = 3)
for (sim in 1:nsims) {
## progress bar
Sys.sleep(0.1)
utils::setTxtProgressBar(progbar, sim)
# simulate ScrData
scrdat <- simulate_scr(true_par, n_occasions, detectors, mesh, ihp = ihp, print = FALSE)
# get starting values for numerical optimiser
start <- get_start_values(scrdat)
# create the model object
obj <- ScrModel$new(form, scrdat, start, print = FALSE)
# fit model
obj$fit()
# store results
ests[[sim]] <- obj$estimates()$par
}
# extract results
mu <- sapply(ests, FUN = function(x){x[,1]})
lcl <- sapply(ests, FUN = function(x){x[,3]})
ucl <- sapply(ests, FUN = function(x){x[,4]})
# distributions
summary(t(mu))
# confidence interval coverage
sum(lcl[1,] < log(true_par$lambda0) & ucl[1,] > log(true_par$lambda0), na.rm=TRUE)
sum(lcl[2,] < log(true_par$sigma) & ucl[2,] >log(true_par$sigma),na.rm=TRUE)
sum(lcl[3,] < log(true_par$D) & ucl[3,] > log(true_par$D), na.rm=TRUE)
sum(lcl[4,] < 0.2 & ucl[4,] > 0.2, na.rm=TRUE)
sum(lcl[5,] < -0.3 & ucl[5,] > -0.3, na.rm=TRUE)
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