highriskzone (version 1.4.9)

det_hrz_eval_ar: Determination of high-risk zone on smaller area of interest (evaluation area) than observation area.

Description

det_hrz_eval_ar determines intensity based highriskzones if bomb crater observations are available for a bigger area than the area of main interest (evaluation area). All observations are used for intensity estimation, the highriskzone is however constructed only in the evaluation area. Either based on specifying a failure probability alpha that indicates the probability of unobserved bombs outside the highriskzone but inside the evaluation area of interest (and not in the overall observation area) (criterion = "indirect"), or by specifying the threshold (maximum intensity of non- exploded bombs outside the) highriskzone directly and intersecting the resulting hrz with the evaluation area (criterion = "direct").

Usage

det_hrz_eval_ar(
  ppdata,
  eval_ar,
  criterion = c("indirect", "direct"),
  cutoff,
  intens = NULL,
  nxprob = 0.1,
  covmatrix = NULL
)

Value

An object of class "highriskzone"

Arguments

ppdata

Observed spatial point process of class ppp in the observation area.

eval_ar

area of interest specified via an object of class owin

criterion

criterion to limit the high-risk zone, can be "indirect" (failure probability alpha) or "direct" (threshold, i.e. maximum intensity of unexploded bombs outside hrz)

cutoff

Value of criterion (alpha or threshold)

intens

(optional) estimated intensity of the observed process (object of class "im") in (bigger) observation area, if not given, it will be estimated using density.ppp.

nxprob

Probability of having unobserved events. Default value is 0.1.

covmatrix

(optional) Covariance matrix of the kernel of a normal distribution, only needed for type="intens" if no intensity is given. If not given, it will be estimated using Hscv.

Examples

set.seed(12412)
spatstat.geom::spatstat.options(npixel=300)
data(craterB)
# reduce number of observations for faster computation
thin.craterB <- craterB[sample(1:craterB$n, 40)]
# define evaluation area of interest
eval.ar <- spatstat.geom::owin(xrange = c(0, 1900), yrange = c(0, 3400), 
               poly = matrix(c(250,250, 1200,1000,250,1000), byrow = TRUE, ncol = 2))

hrzi1 <- det_hrz_eval_ar(thin.craterB, eval_ar = eval.ar, criterion = "direct",
                        cutoff = 3e-6, nxprob = .2)

plot(hrzi1)
plot(thin.craterB, add = TRUE)
plot(eval.ar, add = TRUE)
plot(craterB$window, add = TRUE)